Parts of a Fire Pump – Pump, Driver, Controller, Piping

All 15 parts on the diagram

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Pump unit 6

Fire pump It boosts the water supply for sprinklers and standpipes. This one is a horizontal split-case pump.
Driver (electric motor) Makers call whatever turns the pump the driver. Most often it is a diesel engine or an electric motor.
Coupling Joins the shaft of the driver to the shaft of the pump.
Base plate The pump and its driver are mounted on it together. It is fixed to the foundation.
Controller Starts the pump by itself when the pressure in the system drops. It works with pressure sensors.
Circulation relief valve Lets out a little water when the pump runs with no flow. That keeps the pump case from overheating.

Suction side 4

Suction pipe Brings water to the pump. The water comes from a city main, a tank or another supply.
Suction valve A gate valve that can shut the pump off from its supply. In service it stays fully open.
Suction gauge It reads the pressure of the water arriving at the pump.
Jockey pump Also called the pressure maintenance pump. It makes up the pressure lost to small leaks.

Discharge side 5

Discharge gauge It reads the pressure the pump sends out. Read with the suction gauge, it shows what the pump adds.
Check valve It keeps water from running back through the pump.
Discharge pipe It carries the water on to the sprinkler or standpipe system.
Discharge valve A gate valve after the check valve. In service it stays fully open.
Test header The pump's flow can be run out through it for a test. A line from the discharge side leads to it.

How this list was compiled: Every name checked on 2026-09-30, a name kept only where two independent sources use it. National Fire Protection Association, NFPA 25 (2011 edition), chapter 8 and its annex, full text on archive.org (https://archive.org/details/gov.law.nfpa.25.2011). Two fire pump makers' installation and operation manuals, full text on archive.org (https://archive.org/details/manualslib-id-859 and https://archive.org/details/manualsbase-id-596179). William K. Y. Tao, Mechanical and Electrical Systems in Buildings (1997), passages through archive.org's full-text search (https://archive.org/details/mechanicalelectr0000taow). Wikipedia, Fire pump. No maker is named on the page. Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; a schematic of no maker's equipment, nothing traced. Licence: own work

How it works

A fire pump raises the pressure of the water supply for fire sprinklers and standpipes. The first drawing shows the pump unit from the side with its controller. The second shows the piping, with the pump seen end on.

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The pump unit, then the piping

Numbers 1 to 6 are the pump unit. The fire pump and its driver, here an electric motor, sit on one base plate, joined by the coupling. The circulation relief valve is on the pump, and the controller is on the wall. Numbers 7 to 15 follow the water. It comes in through the suction pipe and the suction valve, past the suction gauge. It leaves past the discharge gauge, through the check valve and up the discharge pipe through the discharge valve. A side line leads through the wall to the test header. The jockey pump sits on a small line in parallel with the fire pump.

A diesel engine can take the place of the electric motor as the driver.
This pump is the horizontal split-case type. Vertical inline, vertical turbine and end suction pumps are also used as fire pumps.

Questions and answers

What are the parts of a fire pump?

The pump, its driver (an electric motor or a diesel engine), the coupling and base plate, and the controller. Around them are the suction and discharge pipes, valves and gauges, a circulation relief valve, a jockey pump and a test header.

What is a jockey pump?

A small pump, also called a pressure maintenance pump, connected near the fire pump. It makes up the pressure lost to small leaks and temperature changes, so the main fire pump does not start for them.

What does a fire pump controller do?

It is the control panel for the pump. Using pressure sensors, it starts the fire pump automatically when the pressure in the sprinkler system drops below a set point.

What is the circulation relief valve on a fire pump?

A small valve on the pump casing, also called a casing relief valve. When the pump runs with no water flowing, it lets a little water out, which keeps the pump case from overheating.