TargetTalk

A number of people at dive shops and scuba divers died or lost limbs when tanks blew up on them. Here is one. You can search and see for yourself. https://www.sanpedrosun.com/accidents-a ... -man-dead/

I saw the results of a blown scuba tank back in the 70s and, while no one died, it blew out a concrete block wall that was filled with sand. I am sure an air pistol/rifle tank would not cause as much damage, but if a piece of metal flew off it could easily kill someone. There is a lot of potential energy stored in a 200BAR (or higher) cylinder.

Chip

Plus how many of you fill your cylinders as slowly as recommended? SCUBA cylinders take quite a while to get to pressure, so the stress on the metal is very low compared to going from say, 1000 psi to 2000 in 3-4 seconds. Aluminum fails "catastrophically", meaning it fragments, rather than develops a single crack slowly. BOOM.

Ricardo wrote: ↑Tue Sep 17, 2019 9:05 pm Plus how many of you fill your cylinders as slowly as recommended? SCUBA cylinders take quite a while to get to pressure, so the stress on the metal is very low compared to going from say, 1000 psi to 2000 in 3-4 seconds. Aluminum fails "catastrophically", meaning it fragments, rather than develops a single crack slowly. BOOM.

With all due respect, you are repeating things that are not factual. Scuba tanks are filled slowly not due to worries of stresses, but rather to reduce compression heating of the gasses which artificially adds to the fill pressure . In fact, most good scuba shops fill the tanks in a water bath for this very reason. The volumes inside a typical airgun tank are so small that compression heating is a non event, It is perfectly fine to rapidly fill them. Additionally, Aluminum is a very different material than ferrous tanks. Aluminum doesn't have a classic ferrous yield curve, Aluminum elongates continually to failure instead of reaching a classic yield point typical with ferrous materials. Our tanks as we use them, are nowhere near an elongation sensitive point and repeatedly cycling them in the pressure range we use them at produces no material creep, and by definition, absent creep, fatigue will not occur. THIS is why the thinking that a gun charged once a month suffers less "wear and tear" than a tank charged daily is incorrect. To hurt the tank, you must pressurize it to a point where creep will occur. and we never get there. For stress calcs, we use 2% material elongation as an equivalent yield value and we are so far under the pressures required to get there that its invisable to us..... Aluminum fracture dynamics are far different than Ferrous materials and in most cases are tears initiating at discontinuities or stress risers usually in the L direction and far less often in the ST direction. This is far different than the notch type failures that ferrous materials exhibit where the grain direction plays a far smaller part in the fracture modality. I hope this helps

SlartyBartFast wrote: ↑Mon Sep 16, 2019 9:17 am

David M wrote: ↑Mon Sep 16, 2019 12:57 amShould the aluminium compressed air cylinder is used beyond the manufacturer-specific service life of 10 years, it is on the shooter’s own responsibility – there is a risk of injury!"

.......
But at ISSF regulated competition (and should include the club, shared, or public ranges, have them check with their insurance providers what they think of not verifying cylinder dates and allowing expired cylinders to be used) GTF over it already. You'll need a cylinder that's within the date limit.

As noted above, this includes ALL USA Shooting sanctioned comps here in the USA.

Inexplicably, CMP has ignored this in their rules.
WHY??? - Because the main rifle firing in CMP youth 3-P airgun comps today is the Crosman CH2009 which has it's cylinder built into the rifle. If the cylinder regs above were applied to CMP comps, the Challenger rifles themselves would either have to be rebuilt or scrapped after 10 years.
(Follow the $$$$)

Tau-7 CO2 pistols are in a similar grey area. If you use CO2 cartridges, it's not clear if the rules apply to the pistol, which has the tank that holds the cartridges brazed onto the frame. If you bulk fill the pistol without cartridges, then the tank that holds the gas is permanently attached. Never mind that the pressures are much lower than PCP, and the amount of gas & energy involved is also much smaller...

I suspect if you showed up at a big match with a Tau-7, they would ban it outright. I was wondering if anyone has actually run into this, or if there has been any sort of official ruling on the matter, either from the ISSF or USA Shooting.

The rule is quite clear as are the PED And DOT regs.
Pressure Vessels regulated by law, carrying CE stamps or DOT marks in our class are end of lifed at 10 years.
Integrated Gun Components that are not regulated pressure vessels as defined in the PED or DOT regs fall outside the limitations listed........

I do not understand the confusion with the TAU7 or Challenger since neither uses a Regulated Pressure Vessel. While they have integrated air storage, it is not in a form covered by pressure vessel law.....

The rule (6.7.6.2) states:
g) It is the athlete’s responsibility that any air or CO2 cylinder is within manufacturer’s validity date (maximum of ten (10) years); this may be checked by Equipment Control and advisory recommendations may be given;

Because "cylinder" is not defined in the rules, all it takes is for an equipment control person to decide that the CO2 cartridges or the Tau-7 tanks are "cylinders", and you've got a problem.

CO2 cartridges are not date stamped. I probably have some that are at least 10 years old...

Ok, I can see where somebody's understanding of the laws and rules might be able to get there, but protecting yourself from human error is difficult at best. The obvious defense is that you are policing manufacturer dates, and since none are present, he can't rule that it is out of date.

As far as 12 GR CO2 or 82 gram CO2 for that matter are concerned. You are correct. They are not date stamped because they fall into a completely different vessel class in the PED..... the above defense is also valid here

BUT those were good concerns and in an ideal world a clarification should be issued....

Good on ya.

spektr wrote: ↑Fri Sep 20, 2019 9:00 am ...... those were good concerns and in an ideal world a clarification should be issued....

And good luck w/ that.
When the Colorado Springs airport began to not allow refillable cylinders of any kind to be checked (prior to the 2012 Olympics), there was an effort to get clarifications issued and corrected for that issue. even as far as getting images of charged cylinders going thru the

Note we still have to mail cylinders out of the OTC, or route travel thru Denver instead of CSPR

The wheels of bureaucracy grind slowly :-) unless you owe them money

Unless you're a big shark:

Don't chew on expired cylinders - that's how we blew up JAWS!:

Love the Garand Pic, thanks