Maybe a strange question, but how low can the pressure go in an O2
cylinder and still have the regulator operate properly? My 20 cubic
foot O2 bottle has lasted almost two years with pretty regular jewelry
torch use (Meco midget and Little Torch). The cylinder pressure is
now down to about 475 lbs on the gage -- how low before I should
consider it empty and get it refilled, as I don't want to run out in
mid-project?

Regards,

Bob

Bob Edwards wrote in message
.. .
Maybe a strange question, but how low can the pressure go in an O2
cylinder and still have the regulator operate properly? My 20 cubic
foot O2 bottle has lasted almost two years with pretty regular jewelry
torch use (Meco midget and Little Torch). The cylinder pressure is
now down to about 475 lbs on the gage -- how low before I should
consider it empty and get it refilled, as I don't want to run out in
mid-project?

Regards,

Bob

Don't worry, you can run it down to the torch pressure before it gives you
any trouble on those small torches.

Paul K. Dickman

Often the gauge does not read very accurately at the low end, so even if
it reads zero on the tank gauge, you might be able to run the torch for
quite some time, especially the small torch. I just noticed that at a
seminar I went to, the tank gauge was zero, but everything kept working,
so we did too. Unless you know the tank gauge, I suggest you just run
it out until it quits working.

Richard



Bob Edwards wrote:

Maybe a strange question, but how low can the pressure go in an O2
cylinder and still have the regulator operate properly? My 20 cubic
foot O2 bottle has lasted almost two years with pretty regular jewelry
torch use (Meco midget and Little Torch). The cylinder pressure is
now down to about 475 lbs on the gage -- how low before I should
consider it empty and get it refilled, as I don't want to run out in
mid-project?

Regards,

Bob

(Bob Edwards) wrote in
m:

Maybe a strange question, but how low can the pressure go in an O2
cylinder and still have the regulator operate properly? My 20 cubic
foot O2 bottle has lasted almost two years with pretty regular jewelry
torch use (Meco midget and Little Torch). The cylinder pressure is
now down to about 475 lbs on the gage -- how low before I should
consider it empty and get it refilled, as I don't want to run out in
mid-project?

Regards,

Bob



What is your low-pressure regulator set to?....the bottle should go down
to roughly that setting before you have real problems.


--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email

You sort of stated your own criterion of when the cylinder should be treated
as empty: there's not enough left in it to get you through the next work
session without worry. You have about 25% of the pressure of a full
cylinder, so you have about 25% of the contents left. At the rate you are
going, with that small torch, you may be able to go for six months or so
without noticing any change in the way your torch runs.

It is good tank ettiquette to close the valve and go for a refill while
there is still *some* pressure left, just so the tank definitely does not
get any air in it. I have never heard of any conseqences to the customer
due to this. When you exchange an empty, they just put it next to the
others ready for refill, and don't even keep track of where it came from.

On Sat, 22 Nov 2003 04:39:19 GMT, "Leo Lichtman"
wrote:


It is good tank ettiquette to close the valve and go for a refill while
there is still *some* pressure left, just so the tank definitely does not
get any air in it.
I have never heard of any conseqences to the customer
due to this. When you exchange an empty, they just put it next to the
others ready for refill, and don't even keep track of where it came from.


Not necessary at all. The first step in refilling is to pull a vacuum
on the cylinder- this is to ensure there is nothing (within reason) in
the cylinder before filling.

-Carl

"Bob Edwards" wrote in message
m...
Maybe a strange question, but how low can the pressure go in an O2
cylinder and still have the regulator operate properly? My 20 cubic
foot O2 bottle has lasted almost two years with pretty regular jewelry
torch use (Meco midget and Little Torch). The cylinder pressure is
now down to about 475 lbs on the gage -- how low before I should
consider it empty and get it refilled, as I don't want to run out in
mid-project?

Regards,

Bob

If it is absolutely critical that you do not run out of gas during
midproject, get a second. If it is not that critical, just use it until no
more gas comes out, then take it in for refilling or swapout.

When I had a commercial shop, I did not want to run out of gas for any
reason. To do so might cost me a couple of days of production if it
happened over the weekend. You have to decide based on your own business.

Steve

SteveB wrote:
If it is absolutely critical that you do not run out of gas during
midproject, get a second. ...

Or just get it refilled when there's still plenty of gas left. Even if
you fill it now with 475 psi left, you've gotten 2 years on 20 cu ft
($20 worth?) of gas.

In article , Leo Lichtman wrote:
You sort of stated your own criterion of when the cylinder should be treated
as empty: there's not enough left in it to get you through the next work
session without worry. You have about 25% of the pressure of a full
cylinder, so you have about 25% of the contents left. At the rate you are
going, with that small torch, you may be able to go for six months or so

directly proportional(?), never thought about it before, but it s/b possible to
calculate the fill "level" from your first pressure reading on the hi side.

it would be approximate, depending on temp and guage accuracy. but what about
the acet.regulators with markings for gas remaining? seems like they could
or you could do the same for other gases. i am surprised i have never seen this
typ of regulator/guage. maybe CO2 fire extinguishers? --Loren

Loren Coe wrote: (clip) but what about the acet.regulators with markings
for gas remaining? seems like they could or you could do the same for other
gases. i am surprised i have never seen this typ of regulator/guage. maybe
CO2 fire extinguishers?
^^^^^^^^^^^^
It's proportional for an ideal gas, and for estimating how much is left,
that's plenty close. Acetylene works a little differently--the gas is
dissolved in a liquid, but I think it is still proportional, which is why
the acetylene tank gauge gives you an idea of the contents remaining.
However, for carbon dioxide and liquefied fuel gases, it's entirely
different. As long as there is liquid in the tank, there is an equillibrium
vapor pressure, regardless of how much is remaining. Generally these tanks
have to be weighed to determine the contents, although there are some tricks
which can be used, such as noticing where the frost-line is on the outside
of a propane tank, or having special valves with quarter-point bleeds.