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Sizing elevator sump pump pipes

asarkisov

Registered User
Joined
Jun 28, 2022
Messages
11
Location
Kansas
Hello all,

I've been reading the IPC commentary to get a better understanding on how to size sanitary pipes connected to an elevator sump pump, however there does not seem to be a firm consensus on how much gpm a pipe can handle at low head. I have two separate elevator shafts, one with only one cabin and the other with three, and have thus sized two separate elevator sumps for 50 gpm and 150 gpm , respectively. The pump needs to only overcome 13' of head and the rest of the flow is gravity fed to an indirect waste connection, my dilemma now is understanding the IPC commentary's explanation on how to size the pipe. They throw out the idea of using a 2 dfu-1 gpm conversion to size the pipe, however this would yield 100 dfu and 300 dfu, respectively, and thus requiring 4" and 6" pipes. However, the commentary also mentions that at low head a 2" pipe is capable of at least 50 gpm. I intend on tying both of my pump lines together which would yield, at most, 200 gpm flowing through a section of pipe before terminating at the indirect waste. Is there any literature out there that exists that can help me size my pipes at low head? 4" and 6" pipes seem a bit overkill in an already crowded plenum space.
 
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I'd use the charts in IPC Appendix E, probably the one for fairly rough pipe (E103.3(6)) to be conservative. It shows a friction loss of 6 psi per 100' of pipe for 50 GPM in a 2" pipe. Add this to the 13 ft. gravity head to get the total head for the pump.
 
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