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A forum to talk about Olympic style shooting, rifle or pistol, 10 meters to 50 meters, and whatever is in between. Hosted by Pilkguns.com
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PostPosted: Mon Feb 20, 2017 9:57 pm 
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Location: Michigan, USA
I have been around scuba and oxygen tanks for 50 years, the only failure that I have seen, a tank that was in a fire. Scuba and oxygen tanks all have a ten year pressure test requirement. Our AP cylinders are not able to be hydro-statically tested economically, because of the built in manometer. Since we can't test them every ten years, we are suppose to discard them. But, our scuba and oxygen tanks don't fail just because they are to be tested. The fact that we can't test them does not mean they are unsafe, it just means we can't prove they are safe. I would never tell anyone to disregard a safety rule, but ..........
Gort


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PostPosted: Tue Feb 21, 2017 12:41 am 
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I have heard of many burst cylinders, there was a defective Walther batch from 2001. But never a word about injuries.

There was another incident in the news where one flew into a dry wall and was stuck there, because the thread was damage.

Manufacturers probably know every serious incident, but they wouldn't report it obviously.


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PostPosted: Tue Feb 21, 2017 9:24 am 
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I shoot my air PCP at the most 6 times a month. Once a week in a 30 shot local match group. Then if I am lucky an organized 60 shot match. I have 2 cylinders. Maybe fill them once a month. This is in the indoor season. Excessive use??? I stand by my earlier statement!!


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PostPosted: Tue Feb 21, 2017 9:54 am 
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Finelld wrote:
I have heard of burst cylinders, but not under normal use. They have either been physically damaged or failed QC checks when they are tested to 150% or more of rated value.


That's the entire purpose of the testing. To induce a failure under test conditions and not in service.

Hence, never fill a damaged cylinder or one whose last test date has expired.

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PostPosted: Tue Feb 21, 2017 10:28 am 
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Location: Staffordshire, United Kingdom
Rover wrote:
OK guys, has any of you heard of a SINGLE burst cylinder?


Yes. A Skanaker/Crossman in a car boot (trunk to you) travelling up the M6 (UK) on a hot day. -- It opened the lid.


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PostPosted: Tue Feb 21, 2017 2:01 pm 
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hundert wrote:
I have heard of many burst cylinders...


Give us a list.


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PostPosted: Tue Feb 21, 2017 2:57 pm 
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Location: San Antonio, TX
Cylinders in hot boots or other places can cause the internal pressure to exceed tolerances. The manual that came with my Hammerli specifically said not to expose filled cylinders to temperatures above 50c or 122f. While these temperatures are not common in Europe they are common in Phoenix where I grew up. They are also common in cars during most of the year here in San Antonio. The ideal gas law explains this PV=nRT. If you increase the temperature the pressure will increase if all else stays the same.


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PostPosted: Tue Feb 21, 2017 3:28 pm 
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Location: Scottsdale AZ
"There was another incident in the news where one flew into a dry wall and was stuck there, because the thread was damage."

I heard about that one, too. Some idiot kid was putting the cylinder off and on the tank with a wrench. We wondered why the tank at our club was getting damaged until we found we also had an idiot in our midst.

What else ya got?


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PostPosted: Tue Feb 21, 2017 3:35 pm 
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Location: Ruislip, UK
Rover wrote:
"There was another incident in the news where one flew into a dry wall and was stuck there, because the thread was damage."

I heard about that one, too. Some idiot kid was putting the cylinder off and on the tank with a wrench. We wondered why the tank at our club was getting damaged until we found we also had an idiot in our midst.

What else ya got?

Well I witnessed a cylinder launch downrange when the thread stripped while the cylinder was being fitted to the gun.

That was nothing to do with the age limit rule though, more bad design by the manufacturer (now corrected).


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PostPosted: Tue Feb 21, 2017 5:01 pm 
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j-team wrote:
Give us a list.


You won't find one, not anything official especially. Even if one did exist it would be under extremely tight lock and key given the potential financial consequences (removal of an entire product line or replacement of an entire part for all users plus reputation damage).

Not stating an opinion on whether or not the cylinder rule is good or not, just stating that such a list, especially one spanning multiple countries, would definitely be on the list of things that a company would not want to be public knowledge. Attorneys here would have a lot of "fun" with that type of information.


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PostPosted: Tue Feb 21, 2017 5:41 pm 
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[quote="Finelld"] ..The ideal gas law explains this PV=nRT. If you increase the temperature the pressure will increase if all else stays the same.[/quote]
Dry air will approximate to an ideal gas. CO2 on the other hand changes pressure hyperbolically above a certain temperature and fill level, and a CO2 tank on the back shelf of a car in Phoenix can indeed explode.

By the way the ideal gas equations use degrees kelvin so an increase of 20 degrees C from 10 to 30 is not actually a huge amount as in the formula it goes from 283 to 303deg K..


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PostPosted: Tue Feb 21, 2017 6:40 pm 
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"By the way the ideal gas equations use degrees kelvin so an increase of 20 degrees C from 10 to 30 is not actually a huge amount as in the formula it goes from 283 to 303deg K.."

Yes, both pressures and temperatures are from absolute zero. We can pretty well neglect the pressure difference for zero to atmospheric of 14.7 psi. In other words, no worries in flying, even on the space shuttle's unpressurized cargo bay. Hard to believe that sunny car temperatures will get even a topped off cylinder over its test limit.

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PostPosted: Tue Feb 21, 2017 9:12 pm 
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Brian Girling wrote:
Rover wrote:
OK guys, has any of you heard of a SINGLE burst cylinder?


Yes. A Skanaker/Crossman in a car boot (trunk to you) travelling up the M6 (UK) on a hot day. -- It opened the lid.


Crossman Skanaker was (is) a CO2 pistol.


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PostPosted: Tue Feb 21, 2017 9:35 pm 
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Location: Twin Cities
Per the DOT
Retesting not required per the note under table 1 in 49 CFR part 180.205. The note reads, "Any cylinder not exceeding two (2) inches in outside diameter and less than two (2) feet in length is exempt from volumetric expansion testing.

Should give rise to more thought. I think this is for CO2 not sure about air


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PostPosted: Tue Feb 21, 2017 10:03 pm 
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johndeere400 wrote:
Per the DOT
Retesting not required per the note under table 1 in 49 CFR part 180.205. The note reads, "Any cylinder not exceeding two (2) inches in outside diameter and less than two (2) feet in length is exempt from volumetric expansion testing.

Should give rise to more thought. I think this is for CO2 not sure about air


Check out this post on the subject: http://www.pyramydair.com/blog/2006/02/scuba-tank-testing-hydrostatic-and-visual-inspection/

He says that
Quote:
Some manufacturers of 10-meter target guns with removable tanks instruct owners to discard their tanks after 20 years. There is no regulation governing that, it’s simply their recommendation. No gun with a fixed reservoir has any recommendation whatsoever. Because the U.S. DOT does not regulate pressure vessels smaller than two inches in outside diameter, they don’t have to do anything. Other countries have different regulations, so check with your nation’s regulatory agency.


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PostPosted: Wed Feb 22, 2017 3:41 am 
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Location: Sydney, Australia
my experience with an 'incident' was not a burst, but a 200/220bar cylinder being filled from a 300 (+?) bar supply. The cylinder FIRMLY embedded itself in a concrete black wall. (Otherwise) Normally sane people will use a spacer to screw a 200baqr cylinder onto a 300bar source....


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PostPosted: Wed Feb 22, 2017 4:11 am 
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j-team wrote:
hundert wrote:
I have heard of many burst cylinders...


Give us a list.


https://forum.waffen-online.de/topic/34 ... tpistolen/

walther recalled those cylinder because they were defective.

Ulrich Eichstädt, who is also a member here in forum, could probably tell you more, he wrote about accidents, but not specific injuries.


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PostPosted: Wed Feb 22, 2017 11:22 am 
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Spencer wrote:
my experience with an 'incident' was not a burst, but a 200/220bar cylinder being filled from a 300 (+?) bar supply. The cylinder FIRMLY embedded itself in a concrete black wall. (Otherwise) Normally sane people will use a spacer to screw a 200baqr cylinder onto a 300bar source....


I think you're missing a "_NOT_" in the above. Or I'm not understanding how a "spacer" makes fills from a higher pressure tank makes the operation safer.

And don't AP and AR cylinders have burst disks installed? F! The primary expected mode of failure due to over pressurisation should NOT be failure of the valve or regulator or the tank bursting. A simple burst disk and the risk of rockets or explosions is eliminated (from over pressurisation, last night while searching I saw stories of exploding paintball tanks from rapid fills).

I don't like trusting my life and limb to people having "common" sense or being "normally" sane. I think it was two deaths from launched CO2 bottles before bottle valves with relief slots on the bottle side threading were made mandatory. Even after the fatal incidents, paintballers were complaining that no one with "common" sense would keep unscrewing a bottle from the valve and would notice the extra length etc.

IMO, clubs should provide and/or only allow regulated fill sources.

For what it's worth, my "common" sense is shouting that much of this discussion complaining about the rules is quite ridiculous without asking someone in the industry for some official legal, technical, and safety comment.

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PostPosted: Wed Feb 22, 2017 11:33 am 
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Location: A new global Great Britain
A tank with a gauge and an instruction leaflet has served us well for many years.

I wouldnt trust my cylinder to your corporate communal fill system either.


Last edited by TenMetrePeter on Wed Feb 22, 2017 11:38 am, edited 1 time in total.

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PostPosted: Wed Feb 22, 2017 11:38 am 
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Location: Montreal, Québec, Canada
TenMetrePeter wrote:
A tank with a gauge and an instruction leaflet had served us well for many years.

I wouldnt trust my cylinder to your corporate communal fill system either.


Then you're just trusting the "common" sense of the people filling.

There is the big advantage that the type of shooting discussed here is one of precision and the shooters are liekly to be more evenly keeled and patient than the average paintball player looking to flash fill their tank and run back to spraying paintballs on the field.

Seems to me you've got some serious issues if you're wary of a commercial regulator and gauges.

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