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

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

"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.

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.

It you have access to a good manual pump, fill the tank completely with
water,(no air bubbles at all!) then connect the suction side of the pump to
a clear plastic tubefull of water and pump to twice rated pressure. Hold it
at that for a few minutes then open a bypass valve to let the water back
into the tube.Any loss of water is an indication that the tank has stretched
and should be scrapped.

Remember this is just a thin walled portable air tank, the kind that
sells new for $20 or less. It has a pop-off valve to prevent
overpressurizing. The gauge on the tank goes red at 120 pis, and I
expect that near that pressure the pop off will open and vent all the
air. If you manually pull the pop off, it will not shut until the tank
is quite low, 70 psi or so, as it has a lot of hysterysis. These type
of tanks doe not even have water drains, so filling it with water would
be quite difficult. First, the whole valve mechanism would have to be
removed and replaced with something different for the test. These tanks
are more like propane tanks than scuba tanks or ASME compresser tanks.
I think that the liability angle is the reason for the date also. But
the question remains, how many of you have one of these that is
expired?
Brad

Tom Miller wrote:
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.

It you have access to a good manual pump, fill the tank completely
with
water,(no air bubbles at all!) then connect the suction side of the
pump to
a clear plastic tubefull of water and pump to twice rated pressure.
Hold it
at that for a few minutes then open a bypass valve to let the water
back
into the tube.Any loss of water is an indication that the tank has
stretched
and should be scrapped.

"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

They test high pressure vessels at 5/3 working pressure. 6/3 might be a
little high.

I would check the popoff and, either set it or install one that is 125% of
working pressure, and pressurize that to see if it works. A wet test may
stress the tank too much.

Just what I would do.

And, adding water to any tank is the main cause of internal corrosion, which
is the main cause of tank failure. That is why the bases of high pressure
tanks are their thickest points.

Steve

wrote in message
ups.com...
Remember this is just a thin walled portable air tank, the kind that
sells new for $20 or less. It has a pop-off valve to prevent
overpressurizing. The gauge on the tank goes red at 120 pis, and I
expect that near that pressure the pop off will open and vent all the
air. If you manually pull the pop off, it will not shut until the tank
is quite low, 70 psi or so, as it has a lot of hysterysis. These type
of tanks doe not even have water drains, so filling it with water would
be quite difficult. First, the whole valve mechanism would have to be
removed and replaced with something different for the test. These tanks
are more like propane tanks than scuba tanks or ASME compresser tanks.
I think that the liability angle is the reason for the date also. But
the question remains, how many of you have one of these that is
expired?
Brad

Tom Miller wrote:
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.

It you have access to a good manual pump, fill the tank completely
with
water,(no air bubbles at all!) then connect the suction side of the
pump to
a clear plastic tubefull of water and pump to twice rated pressure.
Hold it
at that for a few minutes then open a bypass valve to let the water
back
into the tube.Any loss of water is an indication that the tank has
stretched
and should be scrapped.


I don't know. I went and looked at mine, but it is too rusty to see the
date. Other than that, it works fine....................... ;-)

Steve

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

The rust problem is due to pressurizing the tank during humid weather
-- and the resulting water in the tank. I suppose the bottom of the
tank could eventually burst, sending the tank into the air. My tank
weighs about 25lbs. Due to its age I pressurize it only to 100psi. I
wonder how high a potato gun could launch a 25lb object?

wrote in message
ups.com...
Remember this is just a thin walled portable air tank, the kind that
sells new for $20 or less. It has a pop-off valve to prevent
overpressurizing. The gauge on the tank goes red at 120 pis, and I
expect that near that pressure the pop off will open and vent all the
air. If you manually pull the pop off, it will not shut until the tank
is quite low, 70 psi or so, as it has a lot of hysterysis. These type
of tanks doe not even have water drains, so filling it with water would
be quite difficult. First, the whole valve mechanism would have to be
removed and replaced with something different for the test. These tanks
are more like propane tanks than scuba tanks or ASME compresser tanks.
I think that the liability angle is the reason for the date also. But
the question remains, how many of you have one of these that is
expired?
Brad

You're right of course Brad. I guess that I missed that the price was so
low. What I said though, is applicable to the more expensive industrial
pressure vessels. They can be pretty pricey,especially if they're made from
stainless steel.

Tom

Dave wrote:
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


The rust problem is due to pressurizing the tank during humid weather
-- and the resulting water in the tank. I suppose the bottom of the
tank could eventually burst, sending the tank into the air. My tank
weighs about 25lbs. Due to its age I pressurize it only to 100psi. I
wonder how high a potato gun could launch a 25lb object?

For a laugh, take a look at this:

http://www.worldchampionshippunkinchunkin.com/

Chris

"Christopher Tidy" wrote in message
...
Dave wrote:
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


The rust problem is due to pressurizing the tank during humid weather
-- and the resulting water in the tank. I suppose the bottom of the
tank could eventually burst, sending the tank into the air. My tank
weighs about 25lbs. Due to its age I pressurize it only to 100psi. I
wonder how high a potato gun could launch a 25lb object?

For a laugh, take a look at this:

http://www.worldchampionshippunkinchunkin.com/

Chris



I saw the one hour TV program on punkin chunkin. My, them boys get plum
serious about it. The distances were incredible, and the centrifugal
devices were downright scary. If you ever see one of those coming up on TV,
please alert us. It oughta be time for the next one.

Steve

Call me crazy, but I discard mine after the expiration date. They're so
cheap--why take chances?

"Brad Heuver" wrote in message
...
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

Christopher Tidy wrote:
Dave wrote:
[...] My tank weighs about 25lbs. Due to its age I
pressurize it only to 100psi. I wonder how high a
potato gun could launch a 25lb object?

For a laugh, take a look at this:

http://www.worldchampionshippunkinchunkin.com/

Chris

Hmmm... the pumpkins are said to weigh between 8 and 10lbs and are sent
4000+ feet, although they are accellerated through a very, very long
barrel using unknown air pressures.

"Dave" wrote in message
ups.com...
Christopher Tidy wrote:
Dave wrote:
[...] My tank weighs about 25lbs. Due to its age I
pressurize it only to 100psi. I wonder how high a
potato gun could launch a 25lb object?

For a laugh, take a look at this:

http://www.worldchampionshippunkinchunkin.com/

Chris

Hmmm... the pumpkins are said to weigh between 8 and 10lbs and are sent
4000+ feet, although they are accellerated through a very, very long
barrel using unknown air pressures.


There are also mechanical classes, using the centrifugal method, and the
ancient seige machines that hurled rocks. Can't think of that name .....
duh.
Both are quite impressive, and get incredible distances. One of the
centrifugal machines got out of balance on the program I saw, and like a
cement truck with a dried drum of concrete, just about jumped off the
ground.

Steve

I remember seeing this on TLC or something a while back. Some of the rigs
those guys had were pretty trick. Everything from compressed air to
centrifugal arms to trebaches. It was fun to watch, and very impressive to
boot!


"Dave" wrote in message
ups.com...
Christopher Tidy wrote:
Dave wrote:
[...] My tank weighs about 25lbs. Due to its age I
pressurize it only to 100psi. I wonder how high a
potato gun could launch a 25lb object?

For a laugh, take a look at this:

http://www.worldchampionshippunkinchunkin.com/

Chris

Hmmm... the pumpkins are said to weigh between 8 and 10lbs and are sent
4000+ feet, although they are accellerated through a very, very long
barrel using unknown air pressures.