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Question asked by asrulbenjamin on Sep 14, 2020
Latest reply on Sep 14, 2020 by faizal_sharin

Hi, needing help in solving this problem.


Based on NFPA 14 : 1 standpipe can operate maximum flow rate at 379 l/min and for our plant the total standpipe needed is 7 based on theoretical demand rate on each equipment based on NFPA 15.


However, my ME decided to put 9 standpipe due to space limitation which mentioned on NFPA 14 where the valve cannot be located at least 12.2m from the building.


The problem is i need guidance in designing pump sizing which can accommodate all the standpipi.


Total of stand pipe = 9 stand pipe x 379 l/min = 3411 l/min

Taking 150% rated = 3411 l/min = 5116 l/min (9 standpipe consider 150% rated)


For summary centrifugal pump (based on the flowrate above) the nearest capacity for the centrifugal pump is 

-- 5677 l/min (NFPA 20) with 8" suction 8" discharge (nozzle)


1. How do you calculate friction loss along the pipe?

2. Where can i get a calculation sheet in designing a fire pump? (I have in house datasheet but mostly the equation related with API standard).

3. Do you still need to calculate the reynolds number? and everything? such as darcy and churchill? or should I just use hazen-williams formula?