How to Connect Two Fire Pumps in Parallel?

5/27/2026

I have two sets of fire pumps (electric - diesel), one with a discharge of 1000 gpm and a pressure of 160 psi (11 bar), and the other with a discharge of 750 gpm and a pressure of 115 psi (8 bar).

How are these supposed to be arranged if they're to be connected in parallel?

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4 Comments

Anthony

5/27/2026 07:47:11 am

Parallel pumps should have the same discharge pressure. This is a very odd pairing or pump ratings. I'd love more information on the reason for the disparity in ratings.

Baring more information on the pressures, I'd guess this could be a primary electric pump with back up diesel pump set up, though very odd pump selection.

Dan Wilder

5/27/2026 08:02:31 am

Are you looking for redundancy or are these pumps being setup to run at the same time?

Redundancy is just two pumps that connect after the butterfly valve on the discharge side. They would share the Jockey Pump, test header, and some other features....generally shown in A.4.22.1.3(a).

If they are to run together, it gets more complicated with pressure settings for which pump turns on when, you'll need to size the incoming and discharge pipes for both flows at the same time. Sections 4.16.3, 4.16.7 (Closer Look Section in LiNK explains this well), 4.20.6.5, 4.22.1.2 and subsections....just to start you off.

Glenn Berger

5/27/2026 08:18:00 am

Is the two sets of pumps meant for trying to handling different sets of hazards utilizing a common firewater header?

I do not believe that I have been involved with this condition before.

I probably would stage the smaller electric to activate first, followed by the bigger electric, then the bigger diesel, which than only have the smaller diesel activate in a complete failure condition.

Jack G

5/27/2026 08:57:03 am

I d say that these pumps were meant to be in series for a tall high rise .
600 ft tall building ?
Very unusual for these pumps to be in parallel except for different hazards.
The 160 psi pump will require prv s when a minimum of 16 psi city ( 20 residual required) is added.
Are they both diesel or electric or one of each?
A diesel may be a back up to an electric.
If a high rise, it may be the primary to reduce electrical requirements.

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How to Connect Two Fire Pumps in Parallel?

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