Fire Pumps, Tanks, and Water Storage
This domain tests the fire pump performance envelope, the accessories that protect it, and the storage behind it.
The performance envelope
A fire pump must deliver 100 percent of rated flow at rated pressure, at least 150 percent of rated flow at not less than 65 percent of rated pressure, and a shutoff pressure not exceeding 140 percent of rated pressure. Those three points are the basis of every field flow test.
Pump room components
- A jockey pump and controller hold pressure and prevent the main pump from cycling.
- A pressure relief valve protects against overspeed and a circulation relief valve protects against overheating at low flow.
- A test header or a listed flow meter is required for flow testing.
- Suction piping must be sized and arranged to avoid vortices and excessive losses; positive suction head is easier to certify than a lift.
Storage
NFPA 22 covers tanks: an anti-vortex plate on the discharge, a water level indicator, freeze protection, and access for inspection. Stored water is only useful if the level and the heating stay where they belong, which is why inspection routines check them.
Worked example
A pump is rated 1,000 gpm at 100 psi. At 1,500 gpm the gauge must read at least 65 psi, and at shutoff no more than 140 psi. If shutoff reads 155 psi, the pump fails the acceptance criteria even though it easily meets rated flow.
Traps
- Testing only at rated flow and declaring the pump acceptable.
- Confusing the jockey controller setting with the main pump start point.
- Missing the circulation relief valve, which only matters at low flow but protects the pump from overheating.
- Treating a tank level alarm as optional.