K
I've got to disagree with posts made so far. I spent about 8 years working as a field engineer for Airco Industrial Gases (BOC Gases & I think Air Liquide now, I haven't kept track of the mergers). Pressure is pressure, doesn't matter if it's oxygen, nitrogen, helium, hydrogen, etc. What does matter is that guages identified as being cleaned for oxygen service have been specially cleaned to remove all traces of oils, greases, etc. that could react with oxgen and create a mini-bomb. You wouldn't believe what can burn or initiate a fire or explosion in an oxygen line - a particle of rust going too fast in a flow stream and hitting an elbow in a black iron pipe is enough to start a fire that will ignite the pipe!
What is important is that any flowmeters are correctly made for the gas being measured at the pressure and temperature it's being used at. Ideally, your flowmeter has label on it saying for nitrogen @ xyz pressure & yy temperature. Even that is not super critical, as long as you realize that you can develop a revised flow based on the gas, the pressure, the temperature of the gas, and do so. It's not an incredibly hard calculation - we did it a lot in the field for demonstrations when we didn't have the correct flowmeter (We absolutely did not use a fuel gas or notrogen flowmeter in an oxygen line.) On the other hand, that was 20 years ago, so the details are a little vague as to what equations to use. A lot of the flowmeters installed in large lines are pressure and temperature corrected automatically using pressure and temperature sensors.
As to shmos bypassing the planned safety of not being able to add a fuel gas cylinder to an oxygen line, our safety updates were full of very creative ones who managed to do things like that and the resulting catastrophes.
Oxygen safety was something we took seriously - I shut down 2 projects becasue of safety issues. In one, the customer's engineer had rejected our help in sizing piping and had selected a valve that was too small to adequately flow the amount of oxygen needed without exceeding safe velocities. In the second, the plant had cleaned black iron oxygen piping with acetone at the recomendation of their chemist. Acetone leaves a residue that is potentially explosive in an oxygen atmosphere. I refused to permit our piping to be connected to the plant's oxygen lines until the issue was corrected.
What is important is that any flowmeters are correctly made for the gas being measured at the pressure and temperature it's being used at. Ideally, your flowmeter has label on it saying for nitrogen @ xyz pressure & yy temperature. Even that is not super critical, as long as you realize that you can develop a revised flow based on the gas, the pressure, the temperature of the gas, and do so. It's not an incredibly hard calculation - we did it a lot in the field for demonstrations when we didn't have the correct flowmeter (We absolutely did not use a fuel gas or notrogen flowmeter in an oxygen line.) On the other hand, that was 20 years ago, so the details are a little vague as to what equations to use. A lot of the flowmeters installed in large lines are pressure and temperature corrected automatically using pressure and temperature sensors.
As to shmos bypassing the planned safety of not being able to add a fuel gas cylinder to an oxygen line, our safety updates were full of very creative ones who managed to do things like that and the resulting catastrophes.
Oxygen safety was something we took seriously - I shut down 2 projects becasue of safety issues. In one, the customer's engineer had rejected our help in sizing piping and had selected a valve that was too small to adequately flow the amount of oxygen needed without exceeding safe velocities. In the second, the plant had cleaned black iron oxygen piping with acetone at the recomendation of their chemist. Acetone leaves a residue that is potentially explosive in an oxygen atmosphere. I refused to permit our piping to be connected to the plant's oxygen lines until the issue was corrected.

to everyone for their input.