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

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 What don't some of you down in SoCal (only place I know that they do slam/flash fills) take one of your out of date bottles and see how many times it takes it and see what the temps are and such as that.

That would be a good end-of-life program for all of the out of date tanks.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....

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.

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.

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.

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.

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.