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[ChemEng01]

Hey Guys

 

How would you typically size a main relief valve on a firewater pump discharge line where the overpressure case is due to pump overspeed. 

 

I am aware of the table 4.26(a) in NFPA in which a relief valve can be selected directly from the table, however how could I determine the required relief rate in a pump overspeed scenario?

 

In a blocked outlet case I would size for rated capacity at the overspeed condition. However this case is just overspeed as blocked outlet and overspeed would be double jeopardy.

 

Are these valves usually sized based on pump rated flow? 

 

 

Thanks

Edited by ChemEng01, 29 June 2015 - 01:19 AM.