Oxy acetylene regulator question

[Barncat]

I am either having a regulator problem or a set up problem. For oxygen, I turn on slowly, open a full turn or two, then set regulator to about 40psi. When I hit the lever to start cutting, it drops to about 20psi? Is that normal? Do I set the regulator with no gas flow and then leave it? Also, during use, the flow slowly creeps up. After a couple of cuts, the regulator had increased to about 100psi. Am I doing something wrong, or does the regulator need a rebuild?

 

[cathead]

The regulator is supposed to keep the pressure at a certain pressure level. If it isn't doing it,
it must be defective. The proper procedure for opening an oxygen bottle is to open it slowly
and completely until it hits the stop to ensure that there are no leaks.

 

[addertooth]

This can also happen if your main gas valve on the oxygen cylinder is not WIDE open. Some people only open the cylinder valve a turn or two, and experience pressure drop under operation.

 

[LucknowKen]

open a full turn or two, then set regulator to about 40psi.

FWIW I was taught to always fully open the tank valve.

 

[brino]

The proper procedure for opening an oxygen bottle is to open it slowly
and completely until it hits the stop to ensure that there are no leaks.

This can also happen if your main gas valve on the oxygen cylinder is not WIDE open. Some people only open the cylinder valve a turn or two, and experience pressure drop under operation.

FWIW I was taught to always fully open the tank valve.

Very interesting!

My night class at the local community college for oxyacetylene welding said to never open the O2 bottle valve fully.
Full-open for the acetylene, but that was nearly 30 years ago now.
I will have to check some other sources, too.... not that I don't trust you guys......

My initial take on the first symptom here (pressure drop 40-20psi) when cutting was that the O2 bottle was empty or nearly so.
However that cannot explain the pressure creep to 100psi.

-brino


NOTE: PLEASE READ!
I have it backwards here in this post!

Please see all the correct answers below and my update at post 29 in this thread here:
https://www.hobby-machinist.com/threads/oxy-acetylene-regulator-question.96504/post-901927

 

[addertooth]

I missed the part on the creep to 100 psi. That latter part sounds like regulator issues for sure. Extra Pressure has nowhere to come from, other than the regulator.
Also, make sure the regulator is RATED for oxygen.

 

[b4autodark]

Very interesting!

My night class at the local community college for oxyacetylene welding said to never open the O2 bottle valve fully.
Full-open for the acetylene, but that was nearly 30 years ago now.
I will have to check some other sources, too.... not that I don't trust you guys......

My initial take on the first symptom here (pressure drop 40-20psi) when cutting was that the O2 bottle was empty or nearly so.
However that cannot explain the pressure creep to 100psi.

-brino

Always open O2 bottle valves fully as they are double seating valves and are designed to seat in the open position to prevent leakage around the stem.

 

[Barncat]

It is an o2 specific regulator I believe. I was taught only open the acetylene a 1/2 turn, and about 2 on the oxygen

 

[Barncat]

I will try with the oxygen fully open and see if that changes. Hoped have some time this weekend to try. So I set the regulator with no flow at the torch, correct?

 

[LucknowKen]

My night class at the local community college for oxyacetylene welding said to never open the O2 bottle valve fully.

I would wonder why.
I was told (more than 30 yrs ago) that when the valve was fully open it acted as an anti flashback device.
Would like to know if this is true.