LPG bullets operating levels

[kabronic]

I know that to set the operational levers for an atmospheric storage tanks, the code used is API 2350.

But what about an LPG bulk storage bullets. In know about the 80% but , is there any code or regulation for this calculation?

Thanks

 

[Duwe6]

It's not a calculation - it is a "Rule of Thumb" that has worked very well. Just like 'why are there only 42 gallons of diesel in a 55-gal drum?'. In both cases, it supplies the necessary headspace for thermal expansion without ugly consequences.

Remember, please, that 3-Mile Island proved definitively that PRV's are 'positive opening' but may or may not fully reclose. Thus, counting on the PRV(s) on LPG tanks to handle headspace issues is poor practice. They will keep the tank from overpressuring, but you may be left with a big leak in a 98% full tank when they fail to reclose tightly.