"JohnM" wrote in message
...
Brad Heuver wrote:
While filling my 5 gal portable air tank I noticed that the tank has
stamped in it "Discard after 2000" or something like that. I guess I
always knew it was there, its just that for some reason I chose to
start thinking about how long one should really last. It does have
the standard overpressure pop-off valve, which I have manually pulled
to release, but I've never intentionally tried to overpressurize the
tank to check to see if the valve works as intended. The tank has not
seen a lot of usage, and I've never known water to collect in the
bottom of it. I've also never tried to remove the valve to look at
the inside of it either.
So, how long do you keep your spare air tank around? I assume
that rust is the reason that the tanks have a discard date, is that
correct? How likely is the tank to go boom, vs show a sign of a leak
if it was to rust out?
Brad

Brad Heuver

I always figured it had to do with liability issues; expire the tank
before it's expected to ever fail and then hope that flies in any
potential court cases.

I don't blame 'em a bit, there's still some crazy lawsuit stuff going on..

Fill it up with water, pump it up to twice the pressure you use, if you
want to test it..

John

Well, that is the first half of the test (and most important) -- the second
half is they measure how much the tank expands when the water goes
in under pressure -- then how much they get back when the pressure
is removed. It should be the same -- if they get less, it indicates the
tank has stretched (yielded). That is how scuba tanks get holes drilled
in them -- they fail the hydro.