I would be afraid of any tank that had not received a proper ASME
certificate for air service at the pressure you are operating it at.
I hope you never work near the waterheater air receiver -- 15+ years
is fine, it's the few milliseconds it takes for a pinhole to become a
crack and propagate with all that energy and nothing to do but
generate shrapnel that'll get you. (back of the envelope
calculations: 40 gallons of air at 100 psi has about (5.35 ft^3 *
14400 lbf/ft^2) = 77040 lbf-ft of energy -- 233 horsepower if released
in 1/10 sec! so that shrapnel will be moving like a bat out of hades.)
I'm too tired to do the integration right now, but that should be in
the ballpark. The message is it will REALLY hurt when it releases.
And it will release catastrophically.
If you insist on doing this, put a good blast shield (sandbags or
sand-filled block wall; perhaps 3/4" plywood backed by chain link
fencing would work, but I believe in sand for stopping projectiles)
between that bomb and anyplace people might be when it is pressurised,
and put a lid that can catch flying bits over top of it with room for
the air to go somewhere.
(If you want to know why water is safe, let me know. I don't want to
bore everyone who doesn't want to know.)
Donald.
> Date: Tue, 9 Apr 2002 20:00:51 -0700 (PDT)
> From: Martin Scarr <martins@efn.org>
>
>
> On Tue, 9 Apr 2002, john nolon wrote:
>
> > I'd be afraid of a ''newish'' tank... but I wouldn't back away from an old
> > tank... I've got a 30 gallon riveted tank that is old... used it for
>years
> > with 125 psi on it all the time... never failed... the new stuff is thinner
> > material... your body..take your chances..
>
> The new water heaters sold here in my part of Oregon are tested to 300
> psi, and rated at 150 psi working pressure. I've had a used water heater
> tank for a compressor tank for 15+ years with no problems. I drain it
> regularly and have a proper relief valve on it.
>
> Martin Scarr
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