Understanding Pressure Regulators for Gas Cylinders | Expert Help

[sgvaibhav]

Hi,

I wanted to know if pressure regulators connected to gas cylinders provide constant outlet pressure, or provide constant pressure drop.

Example of the regulator that might be used is this.

http://secure.emiratesgas.com/eCom/details.asp?ProductID=ART01661_PR

For instance, I have a gas cylinder having a pressure of 30 bar.
I connect this regulator to the cylinder, and set the regulator to 2 bar.

So will the outlet pressure, coming out from the regulator be 28 bar, or will it be 2 bar?

 

[boneh3ad]

Most regulators provide a constant outlet pressure of whatever you set it to so long as the inlet pressure is higher than your prescribed outlet pressure. The regulator you linked to is of this type.

 

[Travis_King]

The latter. If your regulator is rated for 30 bar inlet pressure and .5-2 bar outlet pressure then you will be able to set the outlet pressure to between .5 and 2 bar when you hook up your 30 bar gas cylinder.

The regulation from most "regulators" comes from pressure drop across an orifice, but the valves themselves function by maintaining constant downstream pressure, not by maintaining constant pressure drop. The flow area in the valve will change based on the pressure setting so that enough flow will pass through the regulator as is required to drop the pressure from 30 bar to 2 bar.

 

[H2o*]

It really depends on the quality of regulator along with the soft parts being suitable for the type of gas you are regulating. (If for a prolonged period.) wether its a constant .5-2 bar set point also depends on what the regulator is feeding into?

 

[sgvaibhav]

Hi,
Trying not to bump the thread, but this is the best place to ask.

Consider this regulator

http://www.newgaz.com/Products/Cat/International_catalogue_2012_BD_P.pdf
Search "002810AC".

Over there it shows outlet pressure 1-3 bar (14-44 psig).
So this 3 bar represents 3 bar gage pressure to atmosphere? i.e 4 bar absolute?

Or it represents 3 bar absolute itself?

 

[H2o*]

1-3 bar.

 

[Travis_King]

14-44 psig translates to 1-3 bar gauge (above atmospheric).

That is to say, at 1 bar on your regulator, the outlet is at roughly 29 psi absolute (14.5 psig). At 3 bar gauge you are at about 58 psia (43.5 psig).

I'd say that in most cases, pressures in piping systems and equipment are talked about in gauge, unless otherwised noted.