Air Tank Explosions and Safety In Filling

[JimD]

The attached report was written for the Navy who use a lot of SCBA tanks on ships for fire fighting. The purpose of the study was to assess the feasibility of extending the life of the tanks another 15 years and assessing tank integrity using a non-destructive test. Apparently thread damage during hydrostatitic tests was their most frequent cause of having to retire a tank. They pull the valve to thread the tank onto the test apparatus. Their conclusion is that a 15 year life extension is fully feasible and use of the NDE technique is also fully feasible. I don't think either has been adopted, however. It is not a terribly difficult paper to read but the NDE discussion is a bit of a distraction.

One interesting comment is they see no correlation of age or number of pressurization cycles to damage to the tank. Physical damage to the carbon fiber or contamination of the tank with water due to failure to remove it after a hydro are the ways their tanks have been damaged. They looked at data from the entire 16 years the Navy has used these tanks. This paper is a key reason I am not worried about continued use of my "expired" Scott SCBA tank.

They also address failure mechanism. No violent ruptures have been experienced. Only slow leaks.

View attachment navy-self-contained-breathing-apparatus-scba-composite-cylinder-life-extension-research-project.pdf

 

[Byrd666]

Thanks yáll. You're teaching me new stuff already.

 

[MEC17670]

Isn't that's what burst disc's are for?
I would worry about your reg or the air vessel on your gun more.

 

[GunshipGuy]

I appreciate the topic. My greatest concern has always been the hose and associated fitting. If the hose were to fail and a blast of air hits your hand, arm or wherever, I think it could do great damage.

 

[Ashiii]

Hello fellow airguners wanted to but together a small video on air tanks, filling and safety.

Thanks again !

Thank you

 

[Ashiii]

Cool video. For anyone interested, that may keep full tanks in their hot car, here is some math.

According to this

How Hot Do Cars Get in the Summer? | Scott's Fort Collins Auto

You may notice the inside of your car becomes extremely hot when parked outside. How hot do cars get in the summer? Can they really reach deadly temperatures?

www.scottsfortcollinsauto.com

A car reaches around 138F peak when 90F outside. Using those delta's you can calculate the new pressure from a tank filled to 4500 psi at 90F sitting in your car that raises the tank temperature to 138F as...

138 *5/9+273.15 = 349.8 Kelvin

4500 / ( 90 * 5/9*273.15) = 6.498

6.498 * 349.8 = 4871 psi


To bring that final number down to 4500 psi peak you would want to keep your tank fills below 4160 PSI.

138 *5/9+273.15 = 349.8 Kelvin

4160 / ( 90 * 5/9*273.15) = 6.498

6.498 * 349.8 = 4503 psi

I am trying not forgetting my tank inside of my car ever

 

[DanT55]

If you read the DOT spec for SCBA tanks they are rated with a safety factory of 3.5x. Any issues will be user related gross mishandling. The spec is very comprehensive. Lots of used tanks out there so if you want to use one over 15yrs old they technically need to be re-certified via acoustic wave to insure future integrity/safety. Dry air is also important for the home fillers as liner corrosion can result in a failure mode.

 

[DesertSilver]

If you read the DOT spec for SCBA tanks they are rated with a safety factory of 3.5x. Any issues will be user related gross mishandling. The spec is very comprehensive. Lots of used tanks out there so if you want to use one over 15yrs old they technically need to be re-certified via acoustic wave to insure future integrity/safety. Dry air is also important for the home fillers as liner corrosion can result in a failure mode.

Problem with the recert is you have to get it recerted every 5 years not hydro.

 

[HogKiller]

I have had a Carbon fiber tank fail, The bands let loose and it lets air out very slow, No boom.
I think safety wise just don't shoot your tank,
Do not fill a gallon (plastic) milk jug with gasoline and put two candles in front and two in the rear and shoot it with a 30-06 stupid is as stupid does,
Mike

Oh silly, you fill your milk jugs with propane THEN shoot them, hydrogen works well too, just ask Hindenburg. In my misspent youth, I use to make hydrogen and fill balloons with it a length of jet-x fuse and let them go at night. This was back before everyone was scared of a boom.

 

[ethannguyen1991]

@Shooting Targets
Greetings,

I understand that I am a newcomer to this platform and currently lack the ability to initiate private messages. Could you kindly reach out to me instead? I am interested in purchasing one of the items you have listed for sale here.

Thank you.

 

[Yardstick]

Has anyone considered doing a proper fatigue analysis on a fill bottle or the air cylinders on their guns? I suspect that's where the recertification/testing time limits come from.