4 replies to this topic

[millany]

good day to all of you! Im a young engineer currently involve in an offsite project for LPG storage. Right now, Im calculating relief requirement for PSV, Most of the PSV's, I handled only has fire case, I wanted to ask for some information regarding Gas expansion due to external fire

Thank you very much for the help

[pleckner]

Gas expansion due to an external fire is a fire case. It's just not a boiling liquid.

For us to be able to help, you must provide more detail as to what you are trying to analyze.

[millany]

I'm analyzing suction drums for Propane refrigerant compressor. Since suction drum contains some liquid, I calculated wetted area, and at the same time consider gas expansion due to fire (since it contains gas), But I think I was wrong since, Gas expansion is only true for system which are not saturated. Am I correct?, I just want someone to elaborate more on Gas expansion due to fire.

Thanks much for the help

[pleckner]

You are basically correct. As long as there is liquid present, it will boil and provide the vaporization rate you need to relieve. You don't need to be concerned about the vapor expansion because the boiling liquid will provide enough pressure to pop your relief device.

Once the liquid has boiled out, you now run into the un-wetted surface area problem. For this, look at API RP521.

If you need anything further, just keep posting your questions. We'll be happy to guide you. Just remember, tell the whole story if possible.

[millany]

Thanks much for the help Mr. Pleckner.