Thoughts on multiple Fire Pump Start/Stop

[aspringe]

Hey guys and gals, was hoping I could get some feedback on some firewater pump settings. We have a suction tank with 40' of head (17 psi), one 100gpm @160psi boost electric jockey pump, and four diesel 2500 gpm @160psi boost PLD pumps. My plan to date is,

Jockey:
Start: 145, Delay: None
Stop: 170, Delay: None
Pump1:
Start: 135, Delay: None
Stop: 170, Delay: 30 min
Pump2:
Start: 130, Delay 15 sec
Stop: 140, Delay 30 min
Pump3:
Start: 125, Delay 30 sec
Stop: 140, Delay 30 min
Pump4:
Start: 120, Delay 45 sec
Stop: 140, Delay 30 min
Pump 5 (spare)
Start: Manual
Stop: Manual

Would be interested in any thoughts from the community with this approach. Cheers!

 

[UFT12]

You do not say what is the churn pressure of your main pumps. From the values you posted I would assume 170 psi unless your pumps have a very flat curve. Assuming 170 psi, the total head at churn conditions is 170+17 = 187 psi. The jockey and (most importantly) the first main pump will start with a delay since their starting pressures are quite lower than 187 psi. There are some good recommendations in NFPA 20 for the subject. It does not mean they have to be strictly followed always (depending on the situation) but in any way very worthy to consider.

Note: per your writings above, 170 psi for main pump 1 stop should be the rating for the total resulting pressure, that is 170 = pump churn pressure + static head of tank which in this case should not be true since 170-17= 153 psi, less than 160 rating pressure. All your above values must be written in terms of total pressures, not just pump individual pressures.

 

[shahad_ff]

Not really regarding the start/stop, i would like to ask you about the capacity of jockey pump (100 GPM?). Are these pumps going to supply ESFR sprinklers only? The idea is to start the main pump (not jockey) if any sprinkler bursts.