AnsweredAssumed Answered

I have a flow requirement of 652.9GPM, which pump should I select?

Question asked by on May 8, 2018
Latest reply on May 8, 2018 by nocivus

As per the Density/Area Curve and Table my total flow requirement is as follows:

Biggest Hazard: Car Park - Ordinary Hazard Group 1 - Area 392m2

As per Figure Density/Area Curves - 4.1(mm/min) x 372(m2) =1525.2L/Min =402.92GPM ..(i)

Further, as per table Total Combined Inside and Outside Hose - 250GPM ....(ii)

Adding .(i) & (ii)

Total Flow required is = 250 + 402.92 =652.915GPM


Now as per NFPA 20, A.4.9 The performance of the (centrifugal) pump when applied at capacities over 140 percent of rated capacity can be adversely affected by the suction conditions. Application of the pump at capacities less than 90 percent is not recommended.   


If I go purely based on the above statement a 500USGPM should be a perfect fit.


But the consultant is forcing to go with a 750GPM pump, if I use a 750GPM pump then how will the pump cater to a flow rate below 90 percent?


Please clear this confusion.