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

[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.




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?

[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.