Ok, here goes a stupid question. Please don’t chastise me for it. I’m looking to buy an air tank to use to fill up my guns in the field. I’ve read that these tanks have a life span of 15 years. If that’s the case then why are people selling used tanks on eBay that have manufactured dates older that 15 years ago. Aren’t these tanks obsolete? Or are they safe to purchase? If a tank is over 15 years old will companies refuse to hydro test them??
Ok, stupid question!
- Thread starter estrike
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Not a stupid question, out of the 15 year life span they cannot be hydro tested the reason people buy them is if the tank is in good condition you can refill yourself if you have a compressor.
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If you are talking about carbon fibre or composite cylinders then yes they are past their legal use by date. There is an expensive process that can extend the life up to a possible extra 15 years but for the average Joe it is not economically viable. Metal SCUBA tanks have no such expiry dates but must be tested regularly. If you see a CF bottle with a birth date that is near or past 15 years old, give it a wide berth.
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It is a saying,"like don't go there"...I'll give it a bye...stay away from..etc..got it,another saying.A berth can be a place to sleep or where ships or boats "park"..or like "give it room" like a rattlesnake,a skunk...or whatever,don't go near it.
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Ah, ok!
So I’m ok with buying metal tanks that are older than 15 years as long as they have been hydro tested recently, correct?
So I’m ok with buying metal tanks that are older than 15 years as long as they have been hydro tested recently, correct?
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That's generally true for aluminum or steel SCUBA tanks, and with the hydro test being within the last five years. However, those tanks typically fill to much lower maximum pressures and can be quite heavy and bulky. In my opinion, CF wrapped SCBA tanks are by far the better option.
Also keep in mind that ANY used tank you buy (even if it is well within the lifespan and hydro tests dates) can still fail it's next inspection or even be unfit for use at the time of purchase based on previous handling. That's a risk you take when buying used tanks regardless of their current certifications.
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It's probably best that you do a little research before you decide what is best for you. Google is your friend. There are traps and pitfalls with buying used pressure vessels. For instance, there was a batch of aluminium SCUBA tanks made in the nineties that were made from dodgy alloy that are still kicking around. I think one or two even burst whilst being filled. If you buy one of those, nobody will fill it because the dive shops have been warned about them and serial number will give it away. Buying a SCUBA tank that is out of test can be a cheap option but it will be a lottery. My brother was given an old steel aqualung tank of Mike Nelson's (Loyd Bridges)Sea Hunt vintage. He sent it off for testing, expecting to get it back in two halves. It came back with a new coat of paint and re certification. As mentioned above, an SCBA tank is the best option in this game but a lower pressure SCUBA tank can be a cheap alternative if you have a gun with a lower max fill limit.
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Here's what I did with an old tank. January last year, I bought a 2006 MSA tank off of Ebay that had about a year left on it's every five year hydro and two years left on it's 15 year certification. My plan was to buy a compressor and fill it myself. I had the tank reinspected and hydro'd at a local fire equipment dealer in a town near mine. This company is listed as an official DOT hydro site. The tank passed hydro and I was told it is in great shape based on the visual inspection. I then took it to a local dive shop to have it filled. The shop could not go past 3000PSI but that was fine for me. This allowed me to fill it past 4000PSI without adding a pressure maintaining valve to my fill rig.
The bottom line is the test gave me confidence that the tank is good.
The bottom line is the test gave me confidence that the tank is good.
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I have bought 2 used scba tanks from a fire fighter store here in PA. Average cost is $50 per year of usable life left. They come filled. If the guy selling me the tank is willing to stand beside it when he fills it, that's good enough for me. He knows more and has seen more with these tanks than I ever will. I have 2 tanks (at $100 each) and that gives me enough high end air pressure for lots of hunting/range time.
This is a low cost solution for me to use PCP's. I'm very comfortable with my purchase and tank conditions. You may feel different though.
This is a low cost solution for me to use PCP's. I'm very comfortable with my purchase and tank conditions. You may feel different though.
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No stupid questions when dealing with 4500 PSI. High pressure air can injure or kill.
Here's a video that shows what a "Failing" tank can do. Granted, this tank failed due to gunshot wound.
https://www.youtube.com/watch?v=3_El-4k7xds
Regardless, when a tank fails, I'd rather be somewhere else.
As for the 15 year lifespan, that's Department of Transportation if I recall. All sorts of regulations around the HPA tanks. 15 years is the legal life span, not necessarily the actual life span. Key is that once it's older than 15, there's only one way to extend the life span with a new kind of Hydro Testing that the US Navy spearheaded. PA sells the extended life tanks, https://www.pyramydair.com/s/a/Air_Venturi_Life_Extended_Carbon_Fiber_Tanks_4500_PSI/8677
With current costs, it seems an expensive way to extend the legal life of a tank.
Anyway, tanks under the kind of pressure we use for airguns, the expansion and contraction of the tanks over time may cause cracks, and cause an eventual failure. No guarantee either way, so it's kind of a crap shoot.
Good luck on the hunt for tanks, it's always an adventure
Here's a video that shows what a "Failing" tank can do. Granted, this tank failed due to gunshot wound.
https://www.youtube.com/watch?v=3_El-4k7xds
Regardless, when a tank fails, I'd rather be somewhere else.
As for the 15 year lifespan, that's Department of Transportation if I recall. All sorts of regulations around the HPA tanks. 15 years is the legal life span, not necessarily the actual life span. Key is that once it's older than 15, there's only one way to extend the life span with a new kind of Hydro Testing that the US Navy spearheaded. PA sells the extended life tanks, https://www.pyramydair.com/s/a/Air_Venturi_Life_Extended_Carbon_Fiber_Tanks_4500_PSI/8677
With current costs, it seems an expensive way to extend the legal life of a tank.
Anyway, tanks under the kind of pressure we use for airguns, the expansion and contraction of the tanks over time may cause cracks, and cause an eventual failure. No guarantee either way, so it's kind of a crap shoot.
Good luck on the hunt for tanks, it's always an adventure
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Thanks for all of the advice everyone! I was able to score some carbon fiber tanks with manufacture dates of 2014 for a great price!
These will keep us happily shooting at my private paintball field
These will keep us happily shooting at my private paintball field
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Allow me to add another question along the same lines, so I don’t think I am high jacking the thread. If a tank is rated to 3000, for example, how can it fill a firearm tank to 4500? I think I I read the earlier poster correctly. Does the overall volume of a larger tank at 3000 can overcome a fill a smaller tank to a higher pressure because the smaller tanks’ smaller volume?
In summary, a large volume can pump a smaller volume to a higher pressure to a certain point and that is why a higher pressure rated source tank can provide more fills to a smaller tank?
In summary, a large volume can pump a smaller volume to a higher pressure to a certain point and that is why a higher pressure rated source tank can provide more fills to a smaller tank?
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A tank/cylinder (even a huge one) with a pressure of 3000psi cannot fill anything to 4500psi (or even to 3000psi technically).
No matter what size the two tanks are, and no matter what their intial pressures are, you will end up with the pressures in both tanks being somewhere between the original pressures of the two tanks.
Do an internet search for "airgun tank fill calculator".
No matter what size the two tanks are, and no matter what their intial pressures are, you will end up with the pressures in both tanks being somewhere between the original pressures of the two tanks.
Do an internet search for "airgun tank fill calculator".
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