1 reply to this topic

[MJT96]

Hi all,

 

Propane cylinders and butane cylinders are made using the same process and have the same wall thickness yet the relief valve set points differ. The only difference I can see is one is usually painted red and the other blue. Something to clarify: the cylinders I refer to here are relatively small quantities in the grand scheme of things, they're the type you'd see on gas BBQ's/patio heaters etc.

 

Propane cylinder set point = 26bar

Butane cylinder set point = 21bar

 

These values are stated in numerous literature locations: LGUK Code of Practice 15, BS5045 (now superseded by BSEN 13593), Tolley's Basic Science and Practice of Gas Service - I could go on... 

 

However this doesn't follow the procedure for sizing a PSV in my experience using API520 as this would mean for the same cylinder you have the same set point regardless of process medium.

 

Can anyone shed some light on this topic? Any input is appreciated - I feel I could be overlooking something obvious!

[Bobby Strain]

I am only guessing. But its likely that this allows the same size PSV for the cylinders. I think the ASME requirements may be different.

 

Bobby

Edited by Bobby Strain, 22 December 2021 - 11:52 AM.