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

[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.