Just out of curosity what is the reasoning against "flash filling"?

[MANN]

I would like someone to explain this to me. Please use math/science/physics/thermodynamics/fluid dynamics in your explanation, and not "because when it cools my tank only says 3500psi"

I already know that a fire/explosion requires 3 elements: heat (ignition), oxygen, & fuel. I know there is a fear that your tank will explode, but there should be no fuel in your tank. If there is you are already doing it wrong.

Does the sudden expansion hurt the aluminum interior/carbon fiber exterior of the tank? I can sorta see it hurting the alum, but the CF I would think would be strong enough to resist the sudden shock of the expansion.

Citing your source would be nice too.

[Sweet Tooth]

Whenever I go to a certain field that flash fills, my fill nipple o rings seems to blow out. I go to a different field that uses a HPA booster, this never happens with the booster. This happens quite frequently with the field that flash fills the tanks. Not just mine, but my friend's tanks, too.

[leloup]

What is flash filling? I assume just jerking down the fill control and filling the hpa tank? If so....oops.

[MANN]

Whenever I go to a certain field that flash fills, my fill nipple o rings seems to blow out. I go to a different field that uses a HPA booster, this never happens with the booster. This happens quite frequently with the field that flash fills the tanks. Not just mine, but my friend's tanks, too.

There are quite a few different designs of fill nipples. I know PE ones are horrible to do what you are talking about. Better ones have never given me problems.

Edit:
None the less that is no reason to not flash fill.

[MANN]

What is flash filling? I assume just jerking down the fill control and filling the hpa tank? If so....oops.

yep....dont worry your not alone.

[maniacmechanic]

Aren't you an Enginering student ? :rolleyes:
This is all of the cuff , " flash filling " is putting a large amount of Air psi / volume through an orifice fast , generating heat , I don't know how much heat it takes to expand a closed container , if said container does expand and it is done over & over & over , I would think it would over time fatigue the container , no matter what it is made of , over time
All metals fatigue over time & work , I work on heavy equipment , I've seen large thick pieces of steel , that one would never think would break , ending up broke & twisted

[y0da900]

When flash filling, you are compressing the air so rapidly that there is a (intense sometimes) build up of heat. That heat, combined with the oxygen rich environment of compressed air, is 2/3 of the ingredients for a single stroke single cycle diesel engine (i.e. tank goes boom). If you have volatile vapors in your tank (caused by using inappropriate lubricants), then it could be very very bad. The less dangerous, but more annoying on a daily basis problem, is that as the tank comes back down to ambient temperature, the pressure drops as well. You can flash fill to 4,500 psi and be left with 3,500 psi in the tank after cooling (with no leaks).

[sjrtk]

Simple explanation I use is the high speed of the flash fill compresses the air in the tank quickly. Causing heat build up and a "false" pressure reading. Then when the tank, and relating compressed air cool to ambient temperature the pressure drops to an actual "accurate" reading. Filling the tank slower reduces the heat build up and the resulting pressure loss. But also as maniac stated it would be less shock load on the material of the tank. The latter possibly (I have no idea how much) reduce the service life of the tank. Best answer i have for you.

[Beemer]

Aren't you an Engineering student ? :rolleyes:
This is all of the cuff , " flash filling " is putting a large amount of Air psi / volume through an orifice fast , generating heat , I don't know how much heat it takes to expand a closed container , if said container does expand and it is done over & over & over , I would think it would over time fatigue the container , no matter what it is made of , over time
All metals fatigue over time & work , I work on heavy equipment , I've seen large thick pieces of steel , that one would never think would break , ending up broke & twisted


^^^^^^THIS...................but here is some more for you.



http://www.nrgnair.com/MPT/02AIR/01air.htm

Ask anyone who has filled scuba tanks about the concern for big temperature change. Dangerous temperature change. Temperature change caused just by moving compressed air, at ambient temperature, from a big tank into a smaller tank at ambient temperature. If the procedure is performed too quickly, there is a very real danger that the smaller tank could explode like a bomb, putting life and limb in great jeopardy.

The question to ponder is, "Where does the energy come from to explode the scuba tank if the max air pressure in the storage tank does not exceed the scuba tank safety test pressure?"

Exploding compressed air tanks constitutes an argument against the "conventional" air car like the MDI which stops to fill its tanks about every 30 miles. Yes, filling can take place in a minute or less, but you would be prudent to be hiding around the corner.

The reason for this dangerous circumstance is based upon the characteristics of suddenly compressing air. Sudden compression of air generates an enormous amount of heat.



http://www.ukpsf.com/documents/hpa.pdf

Make sure that the source of air that you use to fill your bottle is set to deliver air slowly. Bottle fires
require heat to occur, the slower the bottle fills, the less likelihood there is for heat to be generated.
Your bottle should take around 30 seconds for a 0.8L 3000psi to fill, and much longer for a 4500psi 1.1 or 1.5. Be especially careful if you are using an unregulated fill station attached to a dive bottle.

• If your regulator was thread locked on when you bought it, and for some reason you have removed the regulator from the bottle, maybe to fly to another country, the chances are that you have damaged the threads in the bottle and it could be useless. If this is the case, please contact the manufacturer of the bottle and ask them to give you the details for the person who can measure the threads for you to make sure they are still in tolerance.

• Regulators should NEVER be screwed in hand tight to the bottle. All regulators must be torqued tight to the manufacturer’s specifications; again these will be available from the manufacture.


More for you to read in these threads. :cheers:

http://automags.org/forums/showthread.php?t=145106&highlight=flash+fills

http://automags.org/forums/showthread.php?t=219000&highlight=flash+fills

http://automags.org/forums/showthread.php?t=146687&highlight=flash+fills

http://automags.org/forums/showthread.php?t=99764&highlight=flash+fills




___________

http://home.comcast.net/~beemerone/AoIL.gif

[DeuceSV]

When I own my own venue I'm going to have flash-filling... but with strippers filling your tanks.




:ninja:

[sjrtk]

but with strippers filling your tanks.




:ninja:


Well that solves all my moral problems with it.
:cheers:

[leloup]

When I own my own venue I'm going to have flash-filling... but with strippers filling your tanks.




:ninja:

That is still not safe. What about the old men? Let's see - bombs or heart attacks...

[Beemer]

LOL you funny guys..........Keep it on topic. Dont make me remove your useless posts so you can hate on me for removing your useless posts. ;)

This post could self distruct. :ninja:

[DevilMan]

This post could self distruct. :ninja:

If only the post'r would do the same... :p

oh and its dEstruct... :D

DM

[MANN]

Aren't you an Enginering student ? :rolleyes:
This is all of the cuff , " flash filling " is putting a large amount of Air psi / volume through an orifice fast , generating heat , I don't know how much heat it takes to expand a closed container , if said container does expand and it is done over & over & over , I would think it would over time fatigue the container , no matter what it is made of , over time


haha. Yep at least for another year.

I understand 100% of why the heat occurs. I was just thinking what kind of impact it has on our bottles. Most of the info that I have read is geared toward flash filling scuba tanks. Carbon fiber wrapped tanks are not the same, and IMO should not be treated the same.

I wonder if anyone has actually calculated the heat transferred during a fill. I would think that the smallest diameter of the filling process is the fill nipple. So in theory we should be able to calculate the temperature inside the tank assuming an instantaneous fill (which would be worst case scenario because we cannot do so). I kinda doubt that it is that outrageous. I would guess @ 200F. That does not seem to me like that can cause catastrophic failure, and that if it did slightly damage your tank that it would be caught on the next hydro cycle.

I guess I am just not 100% convinced that flash filling is going to "blow up your tank". It seems that there are too many tanks that get flash filled repeatedly and then rehydro just fine.

[koleah]

Ideally:
there should be no fuel in your tank.

However, as you're apparently three years into an engineering degree, you should know there's a difference between "ideally" and "in the real world".

We do a lot of

math/science/physics/thermodynamics/fluid dynamics "ideally", but we need to keep in mind that whatever we're modelling with math/science/physics/thermodynamics/fluid dynamics is still going to be used "in the real world."

"Ideally" we wouldn't need barrel covers either, since markers don't (normally) shoot on their own. . .but "in the real world". . .




(not harshing on you at all though, since I went through engineering school too. Just needs to be kept in mind)

[MANN]

Ideally:

However, as you're apparently three years into an engineering degree, you should know there's a difference between "ideally" and "in the real world".


I agree completely. I think they should teach you "in the real world" more in school. From the experience I have working in environmental engineering I have learned that the textbook is a guideline and not the rule.

Thats why I am asking the question. If "flash filling" is bad due to the risk of ignorant people putting oil in their reg/bad air from the compressors that are filling the tank, or is it something that hurts the structural integrity of the tank.

I am wondering if it the sudden impact of the air, or if it is the heat that allows too much expansion?

There has to be a better solution than taking 20 minutes to filling an HPA tank.

[DevilMan]

Well the places I've been don't take 20 minutes to fill em... but they are not flash filled either.

I would think that the best/safest way would be a system that increased the pressure to just a few PSI over what the tank currently has in it. Meaning if you take it and connect it and it's got 250PSI still in the tank (no you won't know) You connect it up and the fill system starts with 10PSI to the nipple. It increases it by 10PSI every few seconds... You'd have to figure out the timescale that would be the most safe.

I also don't have issue with the way most are filled these days. There is only 1 place that I know of that "flash fills" that I've been to and that was at SC Village I think.

I also know that some goon put a 3K tank on a 45 fill and got it filled. It didn't pop disks or anything. That was an eye opener.

DM

[cockerpunk]

http://www.techpb.com/forum/index.php?showtopic=95958

not just friction too, your essentially re-compressing any air that is the tank, which means more heating.

[hunter100]

A carbon fiber tank is made of three distinct materials: Aluminum, carbon fibers, and an epoxy binder that holds the carbon fibers to the tank. The aluminum can handle temperatures up to a couple hundred farenheit for short times (less than an hour), it will be fine. Carbon fibers are made by reacting plastics at thousands of degrees farenheit, they will be fine at any temperature. The problem is the epoxy binder. Epoxy will oxidize and burn at fairly low temperatures. It can also become more crosslinked and brittle. The function of the epoxy is to transfer the load from the weak aluminum tank onto the strong carbon fibers. So if the epoxy is compromised, then the carbon fiber reinforcing becomes less effective, and your tank is weakened.

You should also specify wether you are filling off a bottle or off a compressor. Off a high pressure bottle, the air is already at 4500 psi, and will actually drop in pressure going to the paintball tank, which results in a lower temperature in the air itself. The warming of the bottle is only from the compression of the air that was in the tank before the fill. If you are filling from a compressor, than you are increasing the pressure from ambient to 4500 psi in the compressor which results in a huge increase in temperature, plus the increase from compressing the gas already in the tank. It is worse to flash fill off a compressor than off a tank.

[cockerpunk]

A carbon fiber tank is made of three distinct materials: Aluminum, carbon fibers, and an epoxy binder that holds the carbon fibers to the tank. The aluminum can handle temperatures up to a couple hundred farenheit for short times (less than an hour), it will be fine. Carbon fibers are made by reacting plastics at thousands of degrees farenheit, they will be fine at any temperature. The problem is the epoxy binder. Epoxy will oxidize and burn at fairly low temperatures. It can also become more crosslinked and brittle. The function of the epoxy is to transfer the load from the weak aluminum tank onto the strong carbon fibers. So if the epoxy is compromised, then the carbon fiber reinforcing becomes less effective, and your tank is weakened.

You should also specify wether you are filling off a bottle or off a compressor. Off a high pressure bottle, the air is already at 4500 psi, and will actually drop in pressure going to the paintball tank, which results in a lower temperature in the air itself. The warming of the bottle is only from the compression of the air that was in the tank before the fill. If you are filling from a compressor, than you are increasing the pressure from ambient to 4500 psi in the compressor which results in a huge increase in temperature, plus the increase from compressing the gas already in the tank. It is worse to flash fill off a compressor than off a tank.

regardless of the source of the high pressure air (tank or compressor) there will be a pressure drop assocated with the flow. and even if you are filling off a compressor, most compressors fill large tanks, then you fill your tank of the large tank. filling from a tank of compressor makes little difference in terms of temprature changes assuming the pressure difference is the same.

[Spider-TW]

I think you would agree that if we put some diesel fuel in a bottle and flash filled it, the diesel would ignite. So let's say that a flash filled bottle reaches autoignition temperature of diesel, about 260C...

http://hypertextbook.com/facts/2005/EileenTang.shtml

IDK which epoxy each bottle maker uses, but you would hope that they use one capable of high temperature. Common loctite 24hr set epoxy has some relatively low temperatures...

http://207.250.200.229:8080/1/doc?id=6350

Without knowing that the tank was designed for flash fill temps, I would at least be concerned that the epoxy touching the aluminum bottle would creep on each fill, causing the bottle to fail it's hydro testing prematurely.

[hunter100]

regardless of the source of the high pressure air (tank or compressor) there will be a pressure drop assocated with the flow. and even if you are filling off a compressor, most compressors fill large tanks, then you fill your tank of the large tank. filling from a tank of compressor makes little difference in terms of temprature changes assuming the pressure difference is the same.

It does matter, a fast compressor works under adiabatic conditions which is why they heat the air up. A bulk tank usually has sat for a long time and cooled back down to room temperature, but is still at 4500 psi. The compressor is delivering hot 4500 psi air to your tank, while the bulk tank is delivering cold 4500 psi air to your tank.

[cockerpunk]

It does matter, a fast compressor works under adiabatic conditions which is why they heat the air up. A bulk tank usually has sat for a long time and cooled back down to room temperature, but is still at 4500 psi. The compressor is delivering hot 4500 psi air to your tank, while the bulk tank is delivering cold 4500 psi air to your tank.

most comrpessors fill a bulk tank that sits there, so its cooled 4500 psi either way. notice how you can fill your tank even when the compressor isn't running? your filling from a bulk tank.

[DoubleDutch]

So... my local shop fills from a storage tank, will it heat up less if I bring them the tank empty, as opposed to having say 1000 psi in it?

They always flash fill, and I end up with about 3900 psi after cooldown usually. When you play outlaw with a Mag, every bit of air counts. Of course, this will all be moot once I get my Shoebox compressor...

[MANN]

I have yet to see any evidence that it is dangerous/bad to flash fill.

-So my tank only has 3900 psi. Who cares I shoot a viking I can still almost get a case.

-Its dangerous because some people put oil in their reg. That sounds like a personal problem. I bet they only do it once.

-The heat will hurt the epoxy? That kinda seems odd. I dont even think that the epoxy matters in carbon fiber. Its the fibers that provide the strength. Correct? ( I am not very knowledgeable w/ CF ) Even if not will the temperature really get that high to hurt the epoxy. Remember firefighters also use carbon fiber air tanks.

It kinda sounds like "you have to wait 30 min after you eat to swim".

[y0da900]

I have yet to see any evidence that it is dangerous/bad to flash fill.


-Its dangerous because some people put oil in their reg. That sounds like a personal problem. I bet they only do it once.



It's a personal problem until:

You visit a field that only lets staff fill HPA tanks
You are behind the guy in line whose father told them to squirt a bunch of 3-in 1 oil in their fill nipple to stop a leak and it gets on the fill whip and subsequently in other people's tanks
You take out the innocent guy waiting in line behind you
Someone who doesn't know any better uses an incompatible oil in the compressor


I don't have links off hand, but you can look around. There have been several instances in the not too distant past where HPA tanks have blown as a direct result of flash filling and improper lubricants that have done some pretty significant damage to people and property.

[Beemer]

I have yet to see any evidence that it is dangerous/bad to flash fill.



I took the time to post links and info. Did you take the time to read ANY of it. I swear this info was in the links I posted.

Here it is right from a Manufacture. Click some linkies.

http://resources.carltech.com/PTD/new_othercomp.html



Paintball Cylinders
Excessive heat due to fast filling can damage a composite pressure vessel!

Rapidly filling a paintball cylinder results in heating of the gas (air/nitrogen) and the cylinder.

If filled too fast, this heat can become excessive resulting in damage to the cylinder.

Such damage can lead to failure of the cylinder, potential property damage and personal injury or death.

Care must be taken to fill the cylinder at a rate so the cylinder temperature does not become too hot to hold in your bare hand (140°F or above).


Now go do some SLAM fills to your tank and get some good temperature readings.

[Frizzle Fry]

I have yet to see any evidence that it is dangerous/bad to flash fill.

The heat can destroy soft parts in the regulator; seen that happen many times.

As far as safety goes, I'm guessing you've never worked at a field or store... Ever seen a tank start to spiderweb, or split at the collar? It's much worse when you're dumping 4500psi in as fast as possible. How about an improperly installed regulator or one with a flaw in the threading sending a bottle across the room like a rocket? Only occurs when slam-filling... You might say such flaws are the result of poor maintenance or handling, but flash filling IS poor handling.


If you don't slow-fill for safety, at least slow-fill so you don't loose 500psi in the temp change? :rolleyes:

[Frizzle Fry]

It kinda sounds like "you have to wait 30 min after you eat to swim".

Straight from Carleton:


"PAINTBALL Cylinders - Excessive heat due to fast filling can damage a composite pressure vessel!

Rapidly filling a paintball cylinder with a compressor or intensifier results in heating of the gas (air/nitrogen) and the cylinder. If filled too fast, this heat can become excessive resulting in damage to the cylinder. Such damage can lead to failure of the cylinder, potential property damage and personal injury or death."


The catergories on their site include "Space", "Aircraft" and "Life Support" in addition to "Paintball" and "Marine". I imagine they've done their homework.

[MANN]

I took the time to post links and info. Did you take the time to read ANY of it. I swear this info was in the links I posted.

I deleted the rest due to the LARGE print. Yes I read every link. All the links within the post were dead due to the threads being a bit old.

The first link you gave was for scuba tanks. While that is a HPA tank I would think that the properties of a carbon fiber are different than just aluminum. None the less it explained why they heat up, and not why it is bad.

The second was a link to a UK based air supplier. Nothing against them, but that was just a basic warning to CYA. It does list a fill rate, but still does not answer the question as to why flash filling is dangerous.

All of the automag.org links I skimmed through with everyone giving their oppinions, but no one really explaining it.

The link that CP gave was useless as well. I completely understand how the pressure goes back down after flash filling.

The link that spider gave me is the reason that we dont put oil in our fill nipples, but not a reason to not flash fill.

The last link that you gave me actually provided some usefull (Ill spare you the sizeX text) information. A link within that page states



Care must be taken to fill the cylinder at a rate so the cylinder temperature does not become too hot to hold in your bare hand (140°F or above).

While this does not explain what is actually failing it is a little more specific in at least giving a recommended temperature to stay away from. Ie a temperature that will damage the tank.

[MANN]

The heat can destroy soft parts in the regulator; seen that happen many times.

As far as safety goes, I'm guessing you've never worked at a field or store... Ever seen a tank start to spiderweb, or split at the collar? It's much worse when you're dumping 4500psi in as fast as possible. How about an improperly installed regulator or one with a flaw in the threading sending a bottle across the room like a rocket? Only occurs when slam-filling... You might say such flaws are the result of poor maintenance or handling, but flash filling IS poor handling.


Owned a store...nope. I was a licensed paintball buisness, and have filled my own tanks since the ~6th grade. CO2 for the first 5 or 6 then on to scubas. I have filled hundreds, and maybe thousands of CO2 tanks without scales, and have only had 1 burst disk iirc rupture on me to date. I have filled quite a few HPA tanks with scubas, and done self serve fields as well.

I have never had a tank do anything that you mentioned. I have always done a form of flash filling. (Always filling a tank within a minute or so)

[MANN]

So now solving "flash filling" problems. Could you not have a ice bath next to a fill station to prevent the tank from reaching 140*F? It wouldn't be hard to place the tank (still attached to the marker) in a tank of water while filling it.

[Frizzle Fry]

So now solving "flash filling" problems. Could you not have a ice bath next to a fill station to prevent the tank from reaching 140*F? It wouldn't be hard to place the tank (still attached to the marker) in a tank of water while filling it.

That's generally what they do for large tanks; fluidic cooling or c02 cooling is common.

[athomas]

So now solving "flash filling" problems. Could you not have a ice bath next to a fill station to prevent the tank from reaching 140*F? It wouldn't be hard to place the tank (still attached to the marker) in a tank of water while filling it.Not only would it cool the tank, but it would add a measure of protection in the event of a failure.

Flash filling is not recommended because the conditions of the flash fill cannot be adequately controlled, even with trained field techs. No one can tell what type of foreign matter may be present in the tank to act as a fuel that could ignite at a high temperature. Also, and more importantly, the lamination of fiber on aluminum tanks can be affected by rapid changes in heat. The aluminum expands at a different rate than the carbon fiber wrap when heated at a very rapid rate. This is the same reason why you shouldn't use both CO2 in your carbon fiber tanks. The rapid cooling while firing CO2 causes uneven rapid cooling between the tank and the fiber wrap and can cause delamination.

[DevilMan]

I think there needs to be a line drawn in the sand here as to what the definition of flash/slam filling is.

I do not consider the fill of 1 minute a flash/slam fill. The fill that I use and see at most places that takes about 30 seconds I don't consider a flash/slam fill.

Again I've only ever been 1 place that I know of that they do the flash/slam fills and that was down in SoCal. You hand your bottle to the guy and he turns around and puts it on the fill whip. hits the button and in less than I'd say 2 seconds your bottle reads 4500. That to me is a flash/slam fill.

Just the over name of flash/slam could be to some people that it's the manifolds that have the buttons that you slam down on to open them up. I have used those as well as the ones with the joystick to open the valve. Neither I would consider a flash/slam fill.

Maybe the definition should be made as to what is what first, as some of us know there is a difference and I think others have never dealt with it. There is a very BIG difference in the two.

DM

[athomas]

I think there needs to be a line drawn in the sand here as to what the definition of flash/slam filling is.

I do not consider the fill of 1 minute a flash/slam fill. The fill that I use and see at most places that takes about 30 seconds I don't consider a flash/slam fill.I was thinking the same thing. A slam fill only takes a couple of seconds to fill a tank.

[Beemer]

So now solving "flash filling" problems. Could you not have a ice bath next to a fill station to prevent the tank from reaching 140*F? It wouldn't be hard to place the tank (still attached to the marker) in a tank of water while filling it.

Sorry for the large type. I fixed it but it seemed like you just werent GETTING it.

A slam/flash fill is ANY fill that creates to much HEAT. Or as I would say one where the pressure drops off after the fill to LESS then a Full fill of what the out put is good for.

But its not a problem, is it? Do some SLAM/FLASH fills and get some temperature readings.

The solution is EASY. It was used at NPPL with 3000psi fills when we first started using HPA back in 92 or so.

AirAmerica got it right at ShatnerBall3 doing the fills. Ask Dan Colby how they did that.

As is with most things Paintball instead of being safe and smart about it we are stupid.

Go show NASA, Carleton, the Dive folks and others how we fill and guess what they will say.
I know I have asked not just on this but on other things as well. I dont ask anymore. Got tired of hearing how stupid we are.

[MANN]

The solution is EASY. It was used at NPPL with 3000psi fills when we first started using HPA back in 92 or so.


What method did they use? I didnt start with HPA until the 2000s.

I dont think that paintball will quit filling tanks fast. Our society wants everything fast. Cooling looks to be the best option atm.

[Beemer]

What method did they use? I didnt start with HPA until the 2000s. Cooling looks to be the best option atm.


Well you all ready know the answer. Nobody likes it. cooling isnt needed.

The best and only way is the SAFE[right] way.

[cockerpunk]

cooling works great, and you get a true 4500 fill (if the tank is at 4500 PSI). you do lose all the energy into the water bath though, so the overall "effienecy" of the compressor and tank system will be lower. so what though?

i think frankly the saftey concerns are a bit unwarrented. the epoxy wont be melting for the heat and the strain rate of a high fill rate wont break or fatgue the metal and fibers.

[Spider-TW]

i think frankly the saftey concerns are a bit unwarrented. the epoxy wont be melting for the heat and the strain rate of a high fill rate wont break or fatgue the metal and fibers.
Did you find some data on bottle epoxy? The common loctite epoxy melts pretty low. I've melted JB weld before. I worked in a lab where they did some composite testing, but I can't remember which epoxy it was, and it wasn't for bottles.

If you're talking about a fill in a few seconds, I doubt a water bath would stop the aluminum liner from getting to about the same temperature as it did before. The increased temperature differential on a tank that was allowed to cool before filling could aggravate the problem (not much, but it may not help at all on temperature).

I doubt there is a serious safety concern from simple delamination. The fiber jacket will probably contain a simple liner fatigue failure. You would get much more liner fatigue if the liner separated from the epoxy and pushed it out in multiple heating and cooling cycles.

The problem is that you cannot design, test, and sell a bottle that you know is safe at all levels of abuse without jacking the price up to military industry standards. If you would pay $1800 instead of $180 for a brand new, high end bottle, you could get a bottle (probably the same one) "designed" for any kind of fill you wanted to do. You just have to pay for the testing. It will cost a lot more if you want to be able to put combustibles in it.

The CYA business is a matter of "here's a product; use it this way; it wasn't tested for anything else". Sometimes you are just pushing the design past the actual rated safety factors that they do have data for.

Until someone builds an automatic slam fill rig and runs a few thousand (or million) cycles on a bunch of bottles, you won't have a full answer. If the manufacturer has done this, they are not going to share the data, and you would have to accept their warnings anyway.

[cockerpunk]

Did you find some data on bottle epoxy? The common loctite epoxy melts pretty low. I've melted JB weld before. I worked in a lab where they did some composite testing, but I can't remember which epoxy it was, and it wasn't for bottles.

If you're talking about a fill in a few seconds, I doubt a water bath would stop the aluminum liner from getting to about the same temperature as it did before. The increased temperature differential on a tank that was allowed to cool before filling could aggravate the problem (not much, but it may not help at all on temperature).

I doubt there is a serious safety concern from simple delamination. The fiber jacket will probably contain a simple liner fatigue failure. You would get much more liner fatigue if the liner separated from the epoxy and pushed it out in multiple heating and cooling cycles.

The problem is that you cannot design, test, and sell a bottle that you know is safe at all levels of abuse without jacking the price up to military industry standards. If you would pay $1800 instead of $180 for a brand new, high end bottle, you could get a bottle (probably the same one) "designed" for any kind of fill you wanted to do. You just have to pay for the testing. It will cost a lot more if you want to be able to put combustibles in it.

The CYA business is a matter of "here's a product; use it this way; it wasn't tested for anything else". Sometimes you are just pushing the design past the actual rated safety factors that they do have data for.

Until someone builds an automatic slam fill rig and runs a few thousand (or million) cycles on a bunch of bottles, you won't have a full answer. If the manufacturer has done this, they are not going to share the data, and you would have to accept their warnings anyway.

are you implying that tank failure is frequent in paintball?

to my knoweldge there isn't a single tank failure in the USA paintball, only reglator and dethreading failures.

seems pretty safe to me ... DOT seems to hav a pretty good test becuase of the sucess rate in the USA.

[nerobro]

I know of a steel tank that blew the bottom off on a slam fill...

[DevilMan]

are you implying that tank failure is frequent in paintball?

to my knoweldge there isn't a single tank failure in the USA paintball, only reglator and dethreading failures.

seems pretty safe to me ... DOT seems to hav a pretty good test becuase of the sucess rate in the USA.

Are you implying that just because you don't know about it that it doesn't exist?

Not any and every failure of something is going to hit the news or be published in the paper or make headlines. Hell man you can't even find a local listing of a major paintball game when it comes to town. So you think that any of the other crap is going to matter to the rest of the populace?

As far as the cooling part... I agree that a water jacket isn't really going to solve the problem. Even if you heat the bottle to 150* it's still going to allow the AL inside the bottle to heat up to some extent before it's able to be cooled back down. And it could also aggravate the problem.

I have an idea... What don't some of you down in SoCal (only place I know that they do slam/flash fills) take one of your out of date bottles and see how many times it takes it and see what the temps are and such as that. See if you can get one to grenade. Granted I would like to know that you guys are protecting yourselves and such, but maybe the field would allow you to do some testing for a day. Just to see. That way there'd be no other people around to get hurt/damaged in the event something does go wrong.

If I had a place up here that I knew did it, I'd be tempted to take an old bottle or two and see what happens.

DM

[Spider-TW]

are you implying that tank failure is frequent in paintball?
Not at all.

I'm saying it is infrequent enough that only the tank manufacturers have enough data to determine the operating conditions of a tank. I can think of reasons for the limitations, but who other than the manufacturer has destroyed enough tanks to know all of the limitations for sure?

Speaking of DOT...they don't specify fill rates do they?

[Spider-TW]

I have an idea... What don't some of you down in SoCal (only place I know that they do slam/flash fills) take one of your out of date bottles and see how many times it takes it and see what the temps are and such as that.

That would be a good end-of-life program for all of the out of date tanks. Get your "deposit" back on a tank with a discount or something (sticker) from the manufacturer.

[classicmagplayer]

cooling works great, and you get a true 4500 fill (if the tank is at 4500 PSI). you do lose all the energy into the water bath though, so the overall "effienecy" of the compressor and tank system will be lower. so what though?

i think frankly the saftey concerns are a bit unwarrented. the epoxy wont be melting for the heat and the strain rate of a high fill rate wont break or fatgue the metal and fibers.


How would there be any measurable difference in efficiency? The compressed air is in a closed system. The thermal energy which is lost to the bath is no different than the thermal energy which is lost to the surrounding air in a normal fill. Even with a slam fill, the thermal energy is the same, and once its dissipated the "efficiency" is also the same.

[halB]

Slow and steady wins the race.

If you take a paper clip, and bend it, it's fine. You bend it back, it's fine. You bend it again and again, and eventually it snaps.

If you subject ANY material to repeated stress, it will eventually fail.

Filling a tank subjects the tank to stress (rapid pressure changes and rapid temperature changes).

Why fill it any faster than you have to? Why push the tank more than you need to? Especially when the tank probably is not maintained properly and is probably abused constantly.

I used to fill up CO2 and HPA. Do you think I'm going to risk my life for your convenience, holding your little "bomb" in my hand? Heck no I am not. I know that you (and by you I mean the majority of players on the field) do not take care of your equipment. I know that you don't even know the stakes and the dangers. And I know that my life is worth a lot more than 30 seconds of your time.

[halB]

That would be a good end-of-life program for all of the out of date tanks. Get your "deposit" back on a tank with a discount or something (sticker) from the manufacturer.


That, right there, is a million dollar idea.

[DevilMan]

How would there be any measurable difference in efficiency? The compressed air is in a closed system. The thermal energy which is lost to the bath is no different than the thermal energy which is lost to the surrounding air in a normal fill. Even with a slam fill, the thermal energy is the same, and once its dissipated the "efficiency" is also the same.

The idea is, that you burn off the heat immediately by keeping the bottle cool while it's on the fill hose. So you get the true 4500 fill or at least closer than you do when you fill to 4500 and then have a 500PSI loss after cool down. Yes the heat transfer is the same, but the time is reduced. Now if you fill to 4500 in a water bath, and you fill to 4500 open air and you fill them the same time and same rate and remove the one from the water bath at the same time then yes I'm sure you'll see little difference.

It's the matter of leaving them in a system that can cool them back off faster so you get a "complete" fill.

Of course there is always that "all day air" thing to contend with... why do you need a FULL fill when you can go back and get more the next time. Well some argue that it's another trip to the fill station and blah blah.... :D

That's the idea for that... but that's a bit OT. Soooo... back to the "Hazards (or NOT) of Flash Filling" with Mann!

DM

[hunter100]

How would there be any measurable difference in efficiency? The compressed air is in a closed system. The thermal energy which is lost to the bath is no different than the thermal energy which is lost to the surrounding air in a normal fill. Even with a slam fill, the thermal energy is the same, and once its dissipated the "efficiency" is also the same.

Correct. It would just be faster to use a water bath or some other cooling method. The heat generated from the air in the tank is independent of the fill rate. However, slowly filling the tank allows for some of the heat to escape through the cylinder wall and keep the total temperature lower. Increasing the temperature gradient with a cold bath also speeds up the flow of heat.

I think water baths are not the way to go however, since careless players would inevitably get water inside their tanks through the fill nipple and water into their guns.

[Spider-TW]

It's the matter of leaving them in a system that can cool them back off faster so you get a "complete" fill.
And that means you have to weigh the rate of cooling in the water bath against a slower fill that doesn't generate the heat in the first place.

I do agree that water baths are good physical protection for tank fills.

[MANN]

Well you all ready know the answer. Nobody likes it. cooling isnt needed.

The best and only way is the SAFE[right] way.

Filling slower is a solution. I am just not sure it is the best solution. I know that I don't want to wait 10-20 min for fills. At large games this would take too long. Owning multiple tanks is a solution, but paintball is expensive enough as it is. I own many, but I know others dont.

Designing a tank that would accept flash/slam fills would be nice, but I doubt cost wise that it is a good solution.

[DevilMan]

Filling slower is a solution. I am just not sure it is the best solution. I know that I don't want to wait 10-20 min for fills. At large games this would take too long. Owning multiple tanks is a solution, but paintball is expensive enough as it is. I own many, but I know others dont.

Designing a tank that would accept flash/slam fills would be nice, but I doubt cost wise that it is a good solution.

Oh I'm sure that making a tank that can handle it wouldn't be all that hard really. But I do think that you'd not want to carry it around. Well anymore than you like lugging around a few extra pounds of gear already. :D

To some it wouldn't matter, to others it would. You know that CF bottles have a MAX LIFE right? Do Scuba/Metal/CO2 bottles? Nope. Not that I know of. I could be wrong here so please if they do let me know. But to the best of my knowledge as long as they are inspected on a regular basis that metal bottles have an unlimited life. Is this true? If so then why not go with 68/45 metal bottles?

I'll let you weigh that one out. :D

DM

[MANN]

Oh I'm sure that making a tank that can handle it wouldn't be all that hard really. But I do think that you'd not want to carry it around. Well anymore than you like lugging around a few extra pounds of gear already. :D

To some it wouldn't matter, to others it would. You know that CF bottles have a MAX LIFE right? Do Scuba/Metal/CO2 bottles? Nope. Not that I know of. I could be wrong here so please if they do let me know. But to the best of my knowledge as long as they are inspected on a regular basis that metal bottles have an unlimited life. Is this true? If so then why not go with 68/45 metal bottles?

I'll let you weigh that one out. :D

DM

Good point. I dont want to carry any more weight than I have already. I know scubas dont expire/go bad. I have one from the early 80s that continues to pass hydro (I know I shouldn't use it tho because of the different alum).

[nerobro]

Slow and steady wins the race.

If you take a paper clip, and bend it, it's fine. You bend it back, it's fine. You bend it again and again, and eventually it snaps.

If you subject ANY material to repeated stress, it will eventually fail.

Filling a tank subjects the tank to stress (rapid pressure changes and rapid temperature changes).
This is only sorta correct. You need to consider the fatigue limit of the material you're working with. If the stresses you put on the material are below the fatigue limit, there will be no damage done.

If you only bend the paperclip a little, you can bend it back and forth forever, without it breaking. However, once you exceed the fatigue limit, you start getting hardening, and cracking, and eventually failure of material.

Carbon fiber has effectively an infinite fatigue limit. Aluminum however, has no fatigue limit. That means if you don't exceed the fail strength of carbon, it will bend back and forth like a spring, forever, without failing. (this does depend somewhat on the binding agent used..) And aluminum, no matter how little you bend it, will accumulate stress and start cracking eventually.

Carbon also has other things to consider. It does not handle heat well. Temperature is the concern here. The epoxy used with carbon fiber does not transfer heat well. And it loses strength quickly with temperature. While a bottle might just feel "warm" to you on the outside, the inside is going to be a WHOLE LOT hotter.

To put that in perspective, find someone who's got a steel 68/3k, and try to even HOLD the bottle after a fast fill. You won't be able to do it. You get the same heat in a fiber bottle too, just you're insulated. The heat is kept within the tank, cooking the aluminum and epoxy.

I remember the first time I had my Maxflow filled. 114ci 3k tank, fiberglass wrapped. Fiberglass tanks are thicker than carbon, by some 1/4" IIRC. That bottle was beyond "warm to the touch" for a good 45 minutes. The tank lost 400psi cooling. I'll bet we can calculate how hot the tank was internally if we were so curious.

[DevilMan]

Good point. I dont want to carry any more weight than I have already. I know scubas dont expire/go bad. I have one from the early 80s that continues to pass hydro (I know I shouldn't use it tho because of the different alum).

It's been said by some that if they would make a 68/45 metal bottle, basically same shape and all as the CF ones that they would be bought/used. But think of it this way... the bottle makers don't want bottles that never die out there. If they do then they'll build themselves out of bizness. If all bottles on the market now were metal and never needed replacing how many of the companies would still be making em?

Building quality things that last is one way to build yourself to death. And when you can't improve on what you have you have nothing new to offer so the same thing happens.

If the bottles all only live for 15 years, the companies know that at least they'll have a new customer of some kind come back around.

DM

[hunter100]

Found these two articles on SCBA filling in water baths, the opinion is its not worth the risks.

The source website is: http://www.fillexpress.com/library/fillfaq.shtml

and the two articles are located at:

http://www.fillexpress.com/library/wetfills.pdf

http://www.fillexpress.com/library/dryfills.pdf

[Spider-TW]

http://www.fillexpress.com/library/wetfills.pdf
Good articles.

I agree baths aren't worth the trouble, but I still like the idea of a little water around a failing bottle. For one, not all the energy is released at once. Second, water loaded demolition charges demonstrate that a little water can provide a lot of force distribution. Maybe not a good thing if your water is full of tree debris.


If the bottles all only live for 15 years, the companies know that at least they'll have a new customer of some kind come back around.

The 15 year thing has always puzzled me too. The only thing I could ever think of was that they figured it was used and cared for the whole time, or not used much and its care would be questionable.

[cockerpunk]

How would there be any measurable difference in efficiency? The compressed air is in a closed system. The thermal energy which is lost to the bath is no different than the thermal energy which is lost to the surrounding air in a normal fill. Even with a slam fill, the thermal energy is the same, and once its dissipated the "efficiency" is also the same.

if you cool a tank without topping it off you lose pressure. so 4500 psi of hot air is probably 4000 psi of that same gass cooled. that energy flows right out of the tank through heat loss. so yes, in a flash fill or a cooled fill the loss will be the same. a slow fill wont have that energy loss.

[nerobro]

The 15 year thing has always puzzled me too. The only thing I could ever think of was that they figured it was used and cared for the whole time, or not used much and its care would be questionable.
The 15 year thing is because the testing method is destructive. Not due to tank condition. Remember, tanks can be retired at any time due to physical damage.

Now, what would have me curious, is how would a tank perform for it's sixth and seventh hydrotests.

[Spider-TW]

The 15 year thing is because the testing method is destructive. Not due to tank condition. Remember, tanks can be retired at any time due to physical damage.

Now, what would have me curious, is how would a tank perform for it's sixth and seventh hydrotests.

Ok. But 3 year and 5 year tanks both have 15 year service lives, don't they? (5 tests versus 3 tests) It also implies a shelf life for a bottle that sat unused for years. It is certainly easier to just say 15 years for all of them, but "easy" is rarely used in a bureaucracy except by oversight. :confused:

[nerobro]

Ok. But 3 year and 5 year tanks both have 15 year service lives, don't they? (5 tests versus 3 tests) It also implies a shelf life for a bottle that sat unused for years. It is certainly easier to just say 15 years for all of them, but "easy" is rarely used in a bureaucracy except by oversight. :confused:
To get a better measure, you'd need to do something silly, like equip the tank with a strain guage to measure tank stretch, a temperature gauge, and a computer to track changes. ;-) you really don't want that.

[DevilMan]

Well one of the issues I have with the whole process is the "destructive testing" part.

I don't think that testing something should be damaging that object. There should/could be better ways, such as XRay and the like to test the bottles. And they should not be subjected to the 9K PSI that the 4500 bottles are put to... I actually think it's 7K or so. Just the same, how many times has a compressor failed and PUT OUT more than 4500 PSI??? It's not something that works that way. You can't have something under pressure fail and have it output MORE pressure than it has already. Keep in mind I'm not talking about a bottle reg failing and allowing tank PSI into the system but the overall way that compressors work and bottles are filled. How many times have you seen a compressor that can pump up the "test" pressure at a field?

There should/could be much safer and far more sane ways to go about the whole process.

DM

[classicmagplayer]

The idea is, that you burn off the heat immediately by keeping the bottle cool while it's on the fill hose. So you get the true 4500 fill or at least closer than you do when you fill to 4500 and then have a 500PSI loss after cool down. Yes the heat transfer is the same, but the time is reduced. Now if you fill to 4500 in a water bath, and you fill to 4500 open air and you fill them the same time and same rate and remove the one from the water bath at the same time then yes I'm sure you'll see little difference.

It's the matter of leaving them in a system that can cool them back off faster so you get a "complete" fill.

Of course there is always that "all day air" thing to contend with... why do you need a FULL fill when you can go back and get more the next time. Well some argue that it's another trip to the fill station and blah blah.... :D

That's the idea for that... but that's a bit OT. Soooo... back to the "Hazards (or NOT) of Flash Filling" with Mann!

DM

I get the idea of the pressure drop due to internal temperature change, and the difference in specific energy and thermal conductivity of water and air, I was just questioning what cockerpunk meant by a bath system having lower efficiency.

I think the OT is a bit ridiculous. Filling a pressure vessel, probably in close proximity to your body, in an uncontrolled manner is just plain stupid.



if you cool a tank without topping it off you lose pressure. so 4500 psi of hot air is probably 4000 psi of that same gass cooled. that energy flows right out of the tank through heat loss. so yes, in a flash fill or a cooled fill the loss will be the same. a slow fill wont have that energy loss.

Yes a slow fill will have the same energy loss. The energy you are saying is lost, its still back in the fill rig. Its the extra moles of air that couldnt transfer because the pressure was already equalized by the hot air inside the tank. Once the hot air cools, the pressure drops and your left with an under-filled tank. A slow fill allows the thermal energy of the hot air to dissipate, lowering the pressure and continuously equalizing with the fill rig.

If you take a tank and slowly fill, the same amount of heat will be generated as if you took that same tank and dump filled it allowed it to cool and topped it off. Its the huge rate difference thats the problem.

[cockerpunk]

I get the idea of the pressure drop due to internal temperature change, and the difference in specific energy and thermal conductivity of water and air, I was just questioning what cockerpunk meant by a bath system having lower efficiency.

I think the OT is a bit ridiculous. Filling a pressure vessel, probably in close proximity to your body, in an uncontrolled manner is just plain stupid.




Yes a slow fill will have the same energy loss. The energy you are saying is lost, its still back in the fill rig. Its the extra moles of air that couldnt transfer because the pressure was already equalized by the hot air inside the tank. Once the hot air cools, the pressure drops and your left with an under-filled tank. A slow fill allows the thermal energy of the hot air to dissipate, lowering the pressure and continuously equalizing with the fill rig.

If you take a tank and slowly fill, the same amount of heat will be generated as if you took that same tank and dump filled it allowed it to cool and topped it off. Its the huge rate difference thats the problem.

no, its the high flow that generates the heat and cuases the pressure drop. a much slower fill will have less pressure loss and shear heating associated with it. more turbulence = more energy lost through heating.

[DevilMan]

Energy can not be created nor destroyed... only changed forms.

The same amount of "energy" is transferred in and around the system. It's just a matter of how much makes it into the bottle. If you fill a 68/45 bottle and it takes you 1 hour to fill it from 0.00000 PSI to 4500 PSI the same amount of "energy" is lost/transferred in the process. Whether or not that energy is significant is the issue. You take that same bottle and fill it in 5 minutes and the SAME amount of energy is made it's the time that changes. You can "feel" it then, you just couldn't "feel" it before. That doesn't mean it didn't happen.

You then take the same bottle same PSI's and fill it from 0 to 4500 in 1 second and you'll more than be able to "feel" the energy that is transferring out of the process.

The SAME amount is gone for all of them. It's just a matter of where it's "lost" from and how damaging it is when it goes.

DM

[hunter100]

hydro testing is not a destructive test and does not limit the life span of the cylinder. The max psi, test pressure, 5 year hydro requirement, and 15 year life cycle are all based on a statistical analysis of the tank data they had when they wrote the specification (like 10 years ago or so). If you recall back when they first introduced the tanks to paintball, they all had 3 year hydro requirements. But the DOT realized after a few years that all the tanks were good for much longer and raised the requirement to 5 years, even for the previous 3 year tanks (if you got them retested). I wouldn't be suprised if they extend the 15 year service life after they collect more data on the tank reliability past 15 years.

There is no absolute criteria that will cause a tank to fail or not fail, its all statistical in nature. The reason you don't overheat your tank is because it increases the chance of failure, but doesn't guarantee it. Why take chances with your own safety?

[DevilMan]

hydro testing is not a destructive test and does not limit the life span of the cylinder. The max psi, test pressure, 5 year hydro requirement, and 15 year life cycle are all based on a statistical analysis of the tank data they had when they wrote the specification (like 10 years ago or so). If you recall back when they first introduced the tanks to paintball, they all had 3 year hydro requirements. But the DOT realized after a few years that all the tanks were good for much longer and raised the requirement to 5 years, even for the previous 3 year tanks (if you got them retested). I wouldn't be suprised if they extend the 15 year service life after they collect more data on the tank reliability past 15 years.

There is no absolute criteria that will cause a tank to fail or not fail, its all statistical in nature. The reason you don't overheat your tank is because it increases the chance of failure, but doesn't guarantee it. Why take chances with your own safety?

The test is destructive because it's in and of itself straining the tank to limits that do damage to the tank. I'm not saying that 4500PSI does no damage, but I am saying that 7K does a good bit more than 4500 does.

Think of it this way.... if you heat something that has a flash point of say 125*F to 120*F over and over and over... it may not like it and it may cause it to weaken. BUT if you heat it to 126*F and the conditions are right, you just ignited the substance. That changes the whole aspect as to what it was to begin with.

It is said that the reason that the tanks are 15 year tanks is because of the expansion/contraction of the tank due to it's life. Yet we all know that there are tanks that get filled and emptied sometimes every weekend and several times that weekend, and others that get used a few times a year. So who is it that came up with the 15 year rule? They said it was from the testing that compromises the structure of the tank that they are only good for X amount of times. I do think that's one of the reasons it changed from 3 to 5... because people got wise with the... "It can only take 2 (5 year tank) tests before it goes bad, but then this tank can take 4 (3 year tank), so what gives?"

So when that happened it went to all 5 year tanks to keep the standard "logical"

Just my .02 on the matter.

DM

[halB]

This is only sorta correct. You need to consider the fatigue limit of the material you're working with. If the stresses you put on the material are below the fatigue limit, there will be no damage done.

If you only bend the paperclip a little, you can bend it back and forth forever, without it breaking. However, once you exceed the fatigue limit, you start getting hardening, and cracking, and eventually failure of material.

Carbon fiber has effectively an infinite fatigue limit. Aluminum however, has no fatigue limit. That means if you don't exceed the fail strength of carbon, it will bend back and forth like a spring, forever, without failing. (this does depend somewhat on the binding agent used..) And aluminum, no matter how little you bend it, will accumulate stress and start cracking eventually.

Carbon also has other things to consider. It does not handle heat well. Temperature is the concern here. The epoxy used with carbon fiber does not transfer heat well. And it loses strength quickly with temperature. While a bottle might just feel "warm" to you on the outside, the inside is going to be a WHOLE LOT hotter.

To put that in perspective, find someone who's got a steel 68/3k, and try to even HOLD the bottle after a fast fill. You won't be able to do it. You get the same heat in a fiber bottle too, just you're insulated. The heat is kept within the tank, cooking the aluminum and epoxy.

I remember the first time I had my Maxflow filled. 114ci 3k tank, fiberglass wrapped. Fiberglass tanks are thicker than carbon, by some 1/4" IIRC. That bottle was beyond "warm to the touch" for a good 45 minutes. The tank lost 400psi cooling. I'll bet we can calculate how hot the tank was internally if we were so curious.


It's not leaving a clip loaded or unloaded that fatigues the spring, both being under the fatigue limit, it is the constant loading and unloading. To use an analogy.

[MANN]

Good articles.

I concur. I read that the upper limit for temperature is 120 for any hp bottle in service. I would like to see what fill rate coincides with this temperature.

[DevilMan]

I concur. I read that the upper limit for temperature is 120 for any hp bottle in service. I would like to see what fill rate coincides with this temperature.

Get a small transmitting thermometer and put it inside of the tank... put on reg and do your fills. Have it transmitting from the get go. Keep an external one as well and keep them sync'd and see what you come up with.

:D Because you know finding an itty bitty thermometer that can transmit and all as well as fit through a 3/4" hole as well as withstand 4500PSI atmospheric pressure is just as easy as going to Home Depot or Lowes or Radio Shack... :D

DM

[OneUp]

When flash filling, you are compressing the air so rapidly that there is a (intense sometimes) build up of heat. That heat, combined with the oxygen rich environment of compressed air, is 2/3 of the ingredients for a single stroke single cycle diesel engine (i.e. tank goes boom). If you have volatile vapors in your tank (caused by using inappropriate lubricants), then it could be very very bad. The less dangerous, but more annoying on a daily basis problem, is that as the tank comes back down to ambient temperature, the pressure drops as well. You can flash fill to 4,500 psi and be left with 3,500 psi in the tank after cooling (with no leaks).
just don't use lube or let an airsmith work it. pv=nrt equation means that normally nonvolatile lube will still be volatile in your tank.

[Spider-TW]

Get a small transmitting thermometer and put it inside of the tank... put on reg and do your fills. Have it transmitting from the get go. Keep an external one as well and keep them sync'd and see what you come up with.

:D Because you know finding an itty bitty thermometer that can transmit and all as well as fit through a 3/4" hole as well as withstand 4500PSI atmospheric pressure is just as easy as going to Home Depot or Lowes or Radio Shack... :D

DM

I would be surprised if the carleton guys didn't at least have a fill head with a pair of solid wires epoxied through it for a temperature probe.

I think that is the only way to know for sure. How about that for a senior project? Anyone? :ninja:

Like cockerpunk says, the friction generates heat. At normal conditions and low flow rates, you can call it ideal gas and trade pressure for temperature. Generally however, you can say that the more violent the transfer, the less reversible the process is (isentropic). Stirling engines are a good example of the highly reversible end. If everything was ideal, and you very carefully (think insulated, for days) let your air roll over from the 70F 4500psi storage tank to your empty 70F bottle, you should have no heat generated. As an integral, you let down the pressure on some air, but then you squeezed it back up.

You could probably measure the heat generation of a fast fill with a calorimeter setup (back to the water bath!). A small styrofoam ice chest might work...

[nerobro]

Get a small transmitting thermometer and put it inside of the tank... put on reg and do your fills. Have it transmitting from the get go. Keep an external one as well and keep them sync'd and see what you come up with.

:D Because you know finding an itty bitty thermometer that can transmit and all as well as fit through a 3/4" hole as well as withstand 4500PSI atmospheric pressure is just as easy as going to Home Depot or Lowes or Radio Shack... :D

DM
PIC 12 series, thermistor, four resistors, and a couple n size batteries. .... and pray it can transmit out of the bottle.

More importantly, running any sort of thermocouple into the tank isn't that hard. You'd need to drill two holes in an existing reg, and epoxy the darned thing shut.

Fill nipples should have a "standard orifice" to restrict fill rates.

[MANN]

regardless of what the heat is tho an ice bath would fix any potential problem. A bag of ice is only a couple bucks. A field would not loose that much by providing a cooler filled with ice water to the players.

[BigEvil]

One of my Dynaflows always blows an on/off oring when it gets flash filled to quickly. I have also seen both a Flateline 4500 and Crossfire 4500 reg seat let go from the same thing. I gotta figure High Pressure + Fast + Heat = bad no matter what. Thats why I love places that let you fill your own tanks.

[nerobro]

regardless of what the heat is tho an ice bath would fix any potential problem. A bag of ice is only a couple bucks. A field would not loose that much by providing a cooler filled with ice water to the players.
With fiber wrapped tanks, I do not believe a bath is the solution. Epoxy and carbon are a blanket over the aluminum bottle. They do not transfer heat well. Beyond that, shocking the tank with ice water isn't going to help the condition of the epoxy or how well the bottle is bonded to the wrapping.

I am also thinking you're underestimating how much ice would be necessary to maintain a cold water bath.

[Spider-TW]

I am also thinking you're underestimating how much ice would be necessary to maintain a cold water bath.
:argh: We would be filling often taking a lot of what hasn't melted with us.

Like BigEvil said, doing your own fills is really nice for the fill rate. I don't like open tables that much though. Anyone that has read any part of this thread would not be one of them, but some people really have no respect for any part of HPA equipment. When you find a bulging and kinked hose at one station, you have to wonder what the next person over is using and what they are doing.

If everybody argued about fill rates and macro lines I would be satisfied. It's the people that don't ask that we have to watch out for.

[nerobro]

And those push button fill rigs have no way of limiting fill speed. :-(

[vf-xx]

I have yet to see any evidence that it is dangerous/bad to flash fill.

-So my tank only has 3900 psi. Who cares I shoot a viking I can still almost get a case.

-Its dangerous because some people put oil in their reg. That sounds like a personal problem. I bet they only do it once.

-The heat will hurt the epoxy? That kinda seems odd. I dont even think that the epoxy matters in carbon fiber. Its the fibers that provide the strength. Correct? ( I am not very knowledgeable w/ CF ) Even if not will the temperature really get that high to hurt the epoxy. Remember firefighters also use carbon fiber air tanks.

It kinda sounds like "you have to wait 30 min after you eat to swim".

Ok, I'll admit that I haven't read the whole thread, so if I'm repeating something, well, it could use repeating.

Next: I did take a graduate level composite material design course, as well as a design through failure analysis course. I haven't run the math, but here are my concerns:

Presurizing and de-pressurizing the tank puts it through a load/unload cycle. This can cause inherent flaws in your pressure vesel to grow. These flaws are microscopic and it may take thousands or millions of cycles for a failure to occur from this. However this only holds true while you're under a set load limit. Exceed this limit and the cycles to failure drops dramatically.

Flash filling may cause localized pressures within the tank to exceed the standard load limits. Yes the bottle is designed with a significant safety margin (hydro to 1.5 MAWP, probably designed to 2.0 or higher). But as stated before, once you exceed a certian load level, you start eating into the expected life of the structure.

The epoxy is CRITICAL in design of a composite material. If you're in ME or something similar I'm sure you've studied stress/strain limits and modulus of elasticity and the like. For homogenous materials (typically metals) these properties are uniform in every direction. For composite materials they are not. You have one set of limits for stress/strain in the direction along the fiber, and nearly NONE perpendicular to your fiber. That's where your epoxy comes in. Again, without knowing the exact physical properties of the epoxy used, I can't calculate the failure limits of the epoxy, but since most binders are thermo set, and not thermo plastic, it's reasonable to assume that a certian level of heat will degrade the epoxy. UV radiation can also degrade some epoxies.

Actually, now that I think about it, it all comes down to whether or not this is a brittle material or a ductile material. I would hazard a guess that a CF tank is a 'brittle' type material. This means that it can be very good at withstanding high loadings, but NOT good withstanding sudden impact forces. Flash filling is a sudden state change, a rapid application of heat AND pressure which may exceed the design limits of the tank over time. Where if you fill slowly, you give the tank a chance to stabilize.

[MANN]

Ok, I'll admit that I haven't read the whole thread, so if I'm repeating something, well, it could use repeating.

Next: I did take a graduate level composite material design course, as well as a design through failure analysis course. I haven't run the math, but here are my concerns:

No thanks. My 400 level CE&ME material science classes are enough to make me realize that I don't want to specialize in material science.



Presurizing and de-pressurizing the tank puts it through a load/unload cycle. This can cause inherent flaws in your pressure vesel to grow. These flaws are microscopic and it may take thousands or millions of cycles for a failure to occur from this. However this only holds true while you're under a set load limit. Exceed this limit and the cycles to failure drops dramatically.

I agree. That is probably why HPA tanks have a 15 yr life. Flash filling does not provide higher pressures just more heat. It will cause the stress strain curve to be modified, but the next cycle should not change the curve. Once the work (I know thats not the term Im looking for) is done putting the same stress/strain will not hurt anything (assuming that you haven't already passed the maximum point).



Flash filling may cause localized pressures within the tank to exceed the standard load limits. Yes the bottle is designed with a significant safety margin (hydro to 1.5 MAWP, probably designed to 2.0 or higher). But as stated before, once you exceed a certian load level, you start eating into the expected life of the structure.

Actually not at all. The regulator from the hpa system are usually set below 4500 so you should never put more than 4500psi in your tank.




The epoxy is CRITICAL in design of a composite material. If you're in ME or something similar I'm sure you've studied stress/strain limits and modulus of elasticity and the like. For homogenous materials (typically metals) these properties are uniform in every direction. For composite materials they are not. You have one set of limits for stress/strain in the direction along the fiber, and nearly NONE perpendicular to your fiber. That's where your epoxy comes in. Again, without knowing the exact physical properties of the epoxy used, I can't calculate the failure limits of the epoxy, but since most binders are thermo set, and not thermo plastic, it's reasonable to assume that a certian level of heat will degrade the epoxy. UV radiation can also degrade some epoxies.

I agree with you here. I am just not sure that heat is that high. After all firefighters use carbon fiber HPA tanks, and they are exposed to higher heats than we put on our tanks.



Actually, now that I think about it, it all comes down to whether or not this is a brittle material or a ductile material. I would hazard a guess that a CF tank is a 'brittle' type material. This means that it can be very good at withstanding high loadings, but NOT good withstanding sudden impact forces. Flash filling is a sudden state change, a rapid application of heat AND pressure which may exceed the design limits of the tank over time. Where if you fill slowly, you give the tank a chance to stabilize.

I agree, but it is impossible to instantaneously fill a tank. I am not sure what is the fastest that you can fill a tank from empty to full (on a 4500psi system), but I would think it would take at least 20 seconds. I am not sure if that is considered "sudden"

[MANN]

With fiber wrapped tanks, I do not believe a bath is the solution. Epoxy and carbon are a blanket over the aluminum bottle. They do not transfer heat well. Beyond that, shocking the tank with ice water isn't going to help the condition of the epoxy or how well the bottle is bonded to the wrapping.

I am also thinking you're underestimating how much ice would be necessary to maintain a cold water bath.

That I am unsure of. I would think that putting the tank in 32* water would be fine, but I have no proof of that. As for amount of ice required to maintain a cold bath. Even if it took 10 bags a day(which it wouldn't that would be better than waiting 10min per fill. I am gearing that more toward larger games. The local field here can pull 70 people. 70 people filling an hpa tank at 10min per fill would be horrible.

[nerobro]

i'm not sure where you're coming from. Remember, our tanks are insulated. So a cold bath isn't going to help matters much.

The fills that worry me are the ones where the tank gets to hot to touch. Figure a 0-5k fill in 10 seconds or less. 20 or 30 seconds is pretty stinking slow by tournament ball standards.

a 30 second fill would make a massive difference.

[athomas]

I agree, but it is impossible to instantaneously fill a tank. I am not sure what is the fastest that you can fill a tank from empty to full (on a 4500psi system), but I would think it would take at least 20 seconds. I am not sure if that is considered "sudden"It is possible to fill a tank at a couple of fields around here in under 10 seconds easily, if required. I'm estimating around 5 seconds. I don't like to do it. It just scares me and the heat factor keeps the fill level down. I like the ability to slow the fill to around 20 seconds. I don't consider a flash fill to be in the 20 second range. It still generates a fair amount of heat though.

[DevilMan]

I REPEAT!!!! SOMEONE NEEDS TO DETERMINE WHAT THE DIFFERENCE IN REGULAR FILL AND FLASH/SLAM FILLING IS!!!!

I would guess that most here have not dealt with FLASH filling...

DM

[Beemer]

I REPEAT!!!! SOMEONE NEEDS TO DETERMINE WHAT THE DIFFERENCE IN REGULAR FILL AND FLASH/SLAM FILLING IS!!!!

I would guess that most here have not dealt with FLASH filling...

DM

Its the same thing. I already posted what it is. Just call it FAST FILL, faster then JimmyJohns.

Fast, Slam, Flash its all the same...............If your fill cools off to less then what the supply was it got filled TO FAST, Slam, Flashed filled.

You need more info. I would bet you could fill a 68/45 with a 4500psi supply in way less then ten minutes and have a full fill. Then again what ever that time is it will STILL be too Sloooooow.

They got it right at Shatner ball 3 and with close to a thousand players I never saw crazy lines for air. ;) And it wasnt no 10 minutes for a fill.

You will need to test temps at different fill rates. Find the max fill rate with out going over temp to get a FULL fill. Thats the safe right way. But like I said paintBall likes being stupid.

[DevilMan]

No Beemer most places I go it takes about 30 seconds I would guess to fill a bottle from 100PSI to 4500PSI... it fills fast at first then slows down as it tops off. Not saying this is the air flow and I know it's because of the the pressure increase...

BUT down at CPP I think it was, you handed your bottle to a person, they went back a few feet and hooked it up to the system, hit a button, disconnected the tank and brought it back to you... the button push took all of 2-4 seconds.

That is what I consider a FLASH/SLAM/whatever fill.

Just trying to clarify to folks the difference. At least to me and some others that have seen it. Maybe this coming weekend some folks could go out and play and take a quick video of the process at various places.

Wouldn't that be easy enough to do?

DM

[Beemer]

^^^^Crazy, scary, stupid stuff eh? :eek:





____________

http://home.comcast.net/~beemerone/AoIL.gif

[DevilMan]

^^^^Crazy, scary, stupid stuff eh? :eek:






its special cause you are special.


The FLASH fill that I saw... yeah it's not something I care to do nor have done to my tanks. But the more common lever pull, or button push that takes it a bit because the air flow is reduced... it makes the bottle warm, but hardly damaging I would guess.

DM

[vf-xx]

I agree. That is probably why HPA tanks have a 15 yr life. Flash filling does not provide higher pressures just more heat. It will cause the stress strain curve to be modified, but the next cycle should not change the curve. Once the work (I know thats not the term Im looking for) is done putting the same stress/strain will not hurt anything (assuming that you haven't already passed the maximum point).

Yes, but heat changes the physical properties of the material, and change can be dramatic over a small temperature range. Not saying it 'is' here, just that it can be. I don't have nearly enough hard data to run the numbers.



I agree with you here. I am just not sure that heat is that high. After all firefighters use carbon fiber HPA tanks, and they are exposed to higher heats than we put on our tanks.

Not sure that this is a valid argument. Do Firefighters use the same tank into high temp multiple times a day, for weeks on end? Also, do Firefighter's SCBA's run at 4.5k? I know SCUBA only runs at 2200. I honestly don't know the answers to these questions.



I agree, but it is impossible to instantaneously fill a tank. I am not sure what is the fastest that you can fill a tank from empty to full (on a 4500psi system), but I would think it would take at least 20 seconds. I am not sure if that is considered "sudden"

While true, but I don't think that the regulator system is perfect, given throttling, temperature issues, and valving, I could see pressure spikes above 4500. They wouldn't last long, but I could see it.

[caylegeorge]

I don't believe this is entirely correct. The warming of the bottle is also from the expansion of the bottle its self.


... The warming of the bottle is only from the compression of the air that was in the tank before the fill.

[Spider-TW]

Not sure that this is a valid argument. Do Firefighters use the same tank into high temp multiple times a day, for weeks on end? Also, do Firefighter's SCBA's run at 4.5k? I know SCUBA only runs at 2200. I honestly don't know the answers to these questions.


I would expect firefighter SCBA tanks to be fiber glass and a specialized resin for the temperature. Fiber glass is not as strong, but twice or more of the melting/degradation temperature of kevlar. Not features you would normally warranty against, except when the kids want to set their markers on fire.

Does the American Composite Manufacturers Association publish any standards?

[nerobro]

I don't believe this is entirely correct. The warming of the bottle is also from the expansion of the bottle its self.
Cycling the material of the bottle, once, for all of a couple fractions of an inch, will not produce any discernible heat.

[DevilMan]

I agree, but it is impossible to instantaneously fill a tank. I am not sure what is the fastest that you can fill a tank from empty to full (on a 4500psi system), but I would think it would take at least 20 seconds. I am not sure if that is considered "sudden"

This isn't true. There are places that can fill a tank in about 1 second. 2 tops. I'm not kidding. Until you find a place that actually does it, you'll more than likely not believe me, but I've seen it done.

DM

[nerobro]

This isn't true. There are places that can fill a tank in about 1 second. 2 tops. I'm not kidding. Until you find a place that actually does it, you'll more than likely not believe me, but I've seen it done.

DM
read: why push button fill stations scare Nerobro.

Ever seen what happens when a fill whip popps off with 4500psi behind it? Screw the tank, I don't wanna get hit with the flail!

[athomas]

read: why push button fill stations scare Nerobro.

Ever seen what happens when a fill whip popps off with 4500psi behind it? Screw the tank, I don't wanna get hit with the flail!I have a friend that got hit in the finger with one. He ended up with a broken bone in his finger. And that was with 3000psi, not 4500.

[nerobro]

They used to enforce some really good rules at fill stations. They don't anymore. :-( Heck, some places like CPX.. you can't even position the gun properly to hold the whip and be out of the way of a failure.

CPX even used to have a fill station that was rigid, that you hung your gun off of when they filled groups of tanks at once. *shivers*

[MANN]

This isn't true. There are places that can fill a tank in about 1 second. 2 tops. I'm not kidding. Until you find a place that actually does it, you'll more than likely not believe me, but I've seen it done.

DM

wow. I have never seen one fill that quickly. I thought the 20-30 seconds was fast. Maybe that is why my tank is not getting that hot.

[Beemer]

Maybe that is why my tank is not getting that hot.

How hot is your tank getting? Do you suffer the pressure drop after a fill syndrome?

[MANN]

How hot is your tank getting? Do you suffer the pressure drop after a fill syndrome?

Defiantly not hot to touch (without the cover on. Here lately I dont use tank covers.). It is warm, but not hot. I have no idea about pressure drop I never look at my pressure gauge. I will next time.

[DevilMan]

Which is why I have mentioned it over and over. I've looked for videos online of the fill process but can't seem to find any.

I do know for a fact that it was down in SoCal for one of the AO shin digs that the place takes your bottle and pops it full FAST! I also know that a 3K bottle got popped full of 4500 PSI and nothing popped loose on it.

If some of you are out this weekend and can get some footage of different places there could be a legitimate comparison.

DM

[hunter100]

I also know that a 3K bottle got popped full of 4500 PSI and nothing popped loose on it.

DM

If I recall correctly, the burst disk on a 3000 psi cylinder goes at 5000 psi, which means everything (the reg, seals, cylinder, etc) should be designed to fail above 5000 psi. Still is scary though.

[DevilMan]

If I recall correctly, the burst disk on a 3000 psi cylinder goes at 5000 psi, which means everything (the reg, seals, cylinder, etc) should be designed to fail above 5000 psi. Still is scary though.

The HP burst disk yes... but what about the LP one? What about the 3K reg with 4500 on top of it?

DM

[hunter100]

The HP burst disk yes... but what about the LP one? What about the 3K reg with 4500 on top of it?

DM

The low pressure disk is 1800 psi, but its after the tank regulator. No matter what the pressure in the tank is, it would only see ~800 psi depending on the output setting of the regulator. That disk should only fail if the regulator seat leaked and let more pressure into the gun. But everything on the high pressure side of the regulator should be designed to withstand 5000 psi so the burst disk is effective.

[DevilMan]

The low pressure disk is 1800 psi, but its after the tank regulator. No matter what the pressure in the tank is, it would only see ~800 psi depending on the output setting of the regulator. That disk should only fail if the regulator seat leaked and let more pressure into the gun. But everything on the high pressure side of the regulator should be designed to withstand 5000 psi so the burst disk is effective.

Yes I know this. Which is why I said what about the 3K reg that has 4500 sitting on it. The point was that 4500 got pumped into a 3K tank.

With that said, why is something designed to not blow off until 5K only allowed to have 3K put into it?

DM

[cockerpunk]

With that said, why is something designed to not blow off until 5K only allowed to have 3K put into it?

DM

factors of saftey.

[DevilMan]

factors of saftey.

Wouldn't the safety factors be better suited to 3500 in a 3K instead of 5K in a 3K when we know that the other "level" is 4500 anyway?

And YES I know the safety factor. The question wasn't one that I didn't know the answer to. It was one that should be pondered by others. But thanx for the answer. :rolleyes:

DM

[cockerpunk]

Wouldn't the safety factors be better suited to 3500 in a 3K instead of 5K in a 3K when we know that the other "level" is 4500 anyway?

And YES I know the safety factor. The question wasn't one that I didn't know the answer to. It was one that should be pondered by others. But thanx for the answer. :rolleyes:

DM

for these things its typically 5/3rds for a saftey factor. so a 3k tank is proof tested to 5k (thus why the burst disk is a 5k), and 4.5ks are tested up to 7.5k (and thats why a 7.5k disk is on them).

the whole tank, regulator, and everything is proof tested (much like a hydro test) when it is made. then the burst disk is installed to make sure that in the event it is over pressurized, the disk will fail (knowing that the tank has already proven itself at higher pressures).

pretty basic fail safe.

[DevilMan]

me thinks you are missin the point here... and I'll try and keep it civil...

The burst disk is there why? To allow a blow off in the event of overpressure. The tank is "tested" to 4500. The burst disk pops at what? 4500?

So when BOTH of the items are set to pop at the same pressure, would you please care to tell me how you determine which one is going to come apart first?

Now would you also like to figure out what makes it different when I can willingly put a 7500 burst disk on a 3K bottle. Because I KNOW that the bottle can handle 5K so why not treat it like a 4500 bottle? When the burst disk, the bottle, and the reg are all tested to 5K.

Do you get it yet?

DM

[DevilMan]

pretty basic fail safe.


Sure thing... if you want to believe that... nothing like hanging yourself from a building on a rope that's rated to hold 300lbs, but is safety tested at 500 and adding a load to your weight that puts it right at 500lbs.

Would you do it?

DM

[cockerpunk]

me thinks you are missin the point here... and I'll try and keep it civil...

The burst disk is there why? To allow a blow off in the event of overpressure. The tank is "tested" to 4500. The burst disk pops at what? 4500?

So when BOTH of the items are set to pop at the same pressure, would you please care to tell me how you determine which one is going to come apart first?

Now would you also like to figure out what makes it different when I can willingly put a 7500 burst disk on a 3K bottle. Because I KNOW that the bottle can handle 5K so why not treat it like a 4500 bottle? When the burst disk, the bottle, and the reg are all tested to 5K.

Do you get it yet?

DM

the inital test proof testing is not a test to failure (that wouldn't make much sense). so the tank is known to be more then strong enough to hold up at above 5k. while the burst disk is known to fail below or at 5k. this way the burst disk will always be the first thing to fail, and when it does, it will fail in a safe way.

treating a 3k tank like a 4.5k tank would eliminate the factor of saftey. thus it would be an unsafe tank that could fail due to weakening by fatuge, damage, or material flaws.

a one time proof test (followed by later proof tests at a given interval) does not mean the tank's working pressure is at that level. it simply means it can, in the event that overpressure does happen, fail in safe manner. that is the purpose of the burst disk, and the factor of safety.

[DevilMan]

the inital test proof testing is not a test to failure (that wouldn't make much sense). so the tank is known to be more then strong enough to hold up at above 5k.

WRONG! It's not tested to hold up ABOVE 5K. It's tested TO 5K. And it's tested with water pressure in a water bath in a vertical position. All of which are different than what the use of the bottle sees. The water provides cooling, the water jacket provides a bit of resistance/pressure to hold it together and the vertical orientation provides NO lateral stress on the bottle. ALL are totally different that what the actual use of the bottle goes through.

DM

[cockerpunk]

WRONG! It's not tested to hold up ABOVE 5K. It's tested TO 5K. And it's tested with water pressure in a water bath in a vertical position. All of which are different than what the use of the bottle sees. The water provides cooling, the water jacket provides a bit of resistance/pressure to hold it together and the vertical orientation provides NO lateral stress on the bottle. ALL are totally different that what the actual use of the bottle goes through.

DM

simple logic my friend.

the only way to know how much pressure a vessel can hold is by testing it to failure. then you can point to the graph and say, wow that cyclender could hold 7.9 ksi! of course that knoweldge is pretty worthless now that the cyclender will no longer function. so you need to not test it to failure. when you do not test to failure, the bounds of the knowledge you gain is that the vessel can hold something above whatever your proof test was at.

think of it this way -

how strong is a rubber band? the only way to find out is to put in on a spring scale, and pull it until it breaks. or, if you had a given task that required it to support 5 pounts, you could proof test it to 12 pounds at the begining of life to insure that it can peform its given task. that rubber band can support at least 12 pounds, so it is capable of performing a task that requires it only supporting 6 pounds.

[DevilMan]

And thank you for proving my point... If it's tested to failure then you know where it breaks.

If you don't you only know it did NOT break up to that point.

Will the burst disk pop at EXACTLY 5K??? What if it's got a 10% variable? Then you have to worry that it could break at 4950, or maybe not break above just above 5K. What if the bottle breaks at 5100??? the burst disk had the 10% window which allowed it to 5500... but the bottle breaks at 5100. Hmmmm...

You jump out of an airplane with a parachute that can handle up to 350lbs. It's been tested to 350lbs and has a 10% window of variance. Would you jump out of that plane with the parachute and have a total load of 375lbs?

DM

[cockerpunk]

And thank you for proving my point... If it's tested to failure then you know where it breaks.

If you don't you only know it did NOT break up to that point.

Will the burst disk pop at EXACTLY 5K??? What if it's got a 10% variable? Then you have to worry that it could break at 4950, or maybe not break above just above 5K. What if the bottle breaks at 5100??? the burst disk had the 10% window which allowed it to 5500... but the bottle breaks at 5100. Hmmmm...

You jump out of an airplane with a parachute that can handle up to 350lbs. It's been tested to 350lbs and has a 10% window of variance. Would you jump out of that plane with the parachute and have a total load of 375lbs?

DM

each pressure vessel is tested to that proof test limit, so there wouldn't ever be a parachute that would hold less then 350 lbs. it would always hold at least 350 lbs if you proof tested each one to 350 lbs.

what point are you trying to make? the saftey features and design of pressure vessels is a pretty established area of engineering, what is your intention? from what i can tell, you have no point or purpose to your posts.

[DevilMan]

each pressure vessel is tested to that proof test limit, so there wouldn't ever be a parachute that would hold less then 350 lbs. it would always hold at least 350 lbs if you proof tested each one to 350 lbs.

what point are you trying to make? the saftey features and design of pressure vessels is a pretty established area of engineering, what is your intention? from what i can tell, you have no point or purpose to your posts.

That's because you are daft.

DM

[hunter100]

I think the most relevant question to this discussion is what is the reliability of the burst disk? If the tank is tested to 5000 psi without failure, but the burst disk doesn't fail until 5100 psi, then it is worthless. I would hope that 99% of the disks fail below the 5000 psi threshold, since that is the testing pressure of the cylinder they are protecting.

[DevilMan]

I think the most relevant question to this discussion is what is the reliability of the burst disk? If the tank is tested to 5000 psi without failure, but the burst disk doesn't fail until 5100 psi, then it is worthless. I would hope that 99% of the disks fail below the 5000 psi threshold, since that is the testing pressure of the cylinder they are protecting.

SEE CP!!!! HE GETS IT!!!!!

DM

[DevilMan]

You would hope Hunter but in effect they are not designed as such. They are designed to fail within a set parameter of 5K. I don't know what that variance is, whether it's 1, 5, 10% etc... but their is room for error.

You are following along that if the max working load of a 3K tank is 3K then the burst disk should be say 3100 or 3500 or something as such. NOT 5K which is the test limit of the tank.

I'm glad to have another bulb come on in this darkness. I was getting lonely with only CP and I here.

DM

[cockerpunk]

burst disks are given a one sided tollerence. +0 psi, -x psi. so that means its a 5k +0 psi -.1k psi, or whatever that tollerence is. at least thats the way we spec brust disks.

[nerobro]

What if the bottle breaks at 5100??? the burst disk had the 10% window which allowed it to 5500... but the bottle breaks at 5100. Hmmmm...
DM
The bottles are actually built to something like 4x working pressure. A 3k tank is built for at least 12kpsi. I've seen tanks that were tested to destruction, IIRC they popped at 18,000 and 23,000psi. They were both 3k carbon bottles.

filling to 5k isn't going to make the bottle fail. That's just the "test pressure." Hydrotesting measures bottle stretch.

[cockerpunk]

The bottles are actually built to something like 4x working pressure. A 3k tank is built for at least 12kpsi. I've seen tanks that were tested to destruction, IIRC they popped at 18,000 and 23,000psi. They were both 3k carbon bottles.

filling to 5k isn't going to make the bottle fail. That's just the "test pressure." Hydrotesting measures bottle stretch.

indeed, the saftey factor on the consutuction of tanks is much larger then the test. testing to failure from batches or validation insures overall quality, while proof testing all tanks makes sure one doesn't slip through the cracks. then the burst disk system prevents that pressure from being exceeded.

its a pretty safe system, the big glarring hole in it is that 5 year hydro interval, a WHOLE lot can happen to a tank in that time to make it unsafe. not that that is even that common, when asked about it, ray from ninja told me that he has yet to see a tank that failed hydro.

[hunter100]

The bottles are actually built to something like 4x working pressure. A 3k tank is built for at least 12kpsi. I've seen tanks that were tested to destruction, IIRC they popped at 18,000 and 23,000psi. They were both 3k carbon bottles.

filling to 5k isn't going to make the bottle fail. That's just the "test pressure." Hydrotesting measures bottle stretch.

The answer to every question in this thread is "Statistics".

You never know for sure what your tank will fail at or what the burst disk will fail at. Statistical analysis predicts a safe operating pressure for the bottle. Putting burst disks on and timely hydrotesting increase the confidence of the statistical prediction. However, you never really know for sure until the tank explodes. This is why you shouldn't overheat your bottle during filling, drop it on the ground, leave it in a hot car, scratch your name in the epoxy, etc. It won't definately cause a failure, but it might increase your chances from 1 in a million to 1 in a thousand.

[teufelhunden]

The answer to every question in this thread is "Statistics".

You never know for sure what your tank will fail at or what the burst disk will fail at. Statistical analysis predicts a safe operating pressure for the bottle. Putting burst disks on and timely hydrotesting increase the confidence of the statistical prediction. However, you never really know for sure until the tank explodes.


You also never really know if you're going to get smacked in the head with an asteroid, but you go outside anyway....

[nerobro]

its a pretty safe system, the big glarring hole in it is that 5 year hydro interval, a WHOLE lot can happen to a tank in that time to make it unsafe. not that that is even that common, when asked about it, ray from ninja told me that he has yet to see a tank that failed hydro.
This bugs me. You can SEE damage that will hurt a tank if you did something stupid. (think fall in a rock garden) So.. the 5 year hydro.. doesn't bother me much.

However, he's never seen a tank fail hydro? .... Well ninja hasn't been around "that" long.

[cockerpunk]

This bugs me. You can SEE damage that will hurt a tank if you did something stupid. (think fall in a rock garden) So.. the 5 year hydro.. doesn't bother me much.

However, he's never seen a tank fail hydro? .... Well ninja hasn't been around "that" long.

more correctly, he said he couldn't remember a tank having failed.

ninja has been around since the early days of compressed air in paintball. they used to make the old PMI pure energy regs when they first came out, WGP, DXS and others. only when all of those started getting outsourced to china did ninja come on-line as there own brand.

the company is PSI specialists IIRC.

[Shane-O-Mac]

Few things from my time as an AA tourney tech, learned form the engineers and Dan Colby himself.

HP burst disks burst at 7.5k when NEW. When filled many times the disc weakens like the paper clip analogy, thats the real reason any HP burst disc blows, fatigue, not over pressurization. A 3000psi tanks HP disc is 5k, but gets lower as metal fatigue sets in.

Flash fills are hard on the regulator, fill nipple and the tank. What is a flash fill? A fill that raises the temp of the tank above 130* if I recall correctly, just not sure of the actual temp that DOT has set. At one Chicago NPPl we covertly used a laser temp gun and got tank temp readings OVER 130*, that is a dangerous temp for a pressure vessel. Again if I recall correctly, following DOT guidelines, a pressure cylinder (HPA and Co2) must be destroyed after being exposed/raised above 130*. Again I might be off on the actual temps, but its been awhile since I had to quote those rules....LOL.

Hydro testing is destructive. They fill the tank to 7.5k for a 4500 tank in a water column. They measure the amount of water displaced when the tank fills (yes the tank expands) and how much is replaced (not all is replaced FYI) when depressurized. The amount of water left in the measuring device is the REE measurment in CC's. If the amount of water left has to be less than the REE number on your tank. So your expanding your tank much more than normal, so it will have some negative impact on the tank. Is it enough to reduce the tanks life? I would guess not. I have seen a tank not pass hydro for not contracting back as much as it should have. It came back with a hole drilled into it so it could not be used again. Most tank failures I have seen were from damaged threads for the regulator. And a few were failed by visual inspection, mostly huge gouges in the tank.


MANN: As for why not to flash fill, well are the extra 20-30 seconds filling a tank worth the risk to you and others around you? Are you in THAT much of a hurry?

Devilman: HP discs are 7.5k for 4.5k tank, and 4.5k for a 3k tank. This has been THE standard for years and years. Nerobro is right, tanks have been detroyed to see what the burst preesure is and it was over 12k. So think about this, how often can you get a fill over 5k? And that 5k fill is very hard to get also, so your worrying about something that has almost NO chance of happening. There are some fill stations that use 6k bulk tanks, but that is rare (and expensive), and will still have a problem getting much higher than a 5k fill. And regulators are built to withstand higher than 5k fills, just to throw that out there.

[TnDeathInc]

flash fills w/o a doubt almost always blow my fill nipple orings




Straight from Carleton:


"PAINTBALL Cylinders - Excessive heat due to fast filling can damage a composite pressure vessel!

Rapidly filling a paintball cylinder with a compressor or intensifier results in heating of the gas (air/nitrogen) and the cylinder. If filled too fast, this heat can become excessive resulting in damage to the cylinder. Such damage can lead to failure of the cylinder, potential property damage and personal injury or death."


The catergories on their site include "Space", "Aircraft" and "Life Support" in addition to "Paintball" and "Marine". I imagine they've done their homework.