Jockey Pump Cycling and Main Fire Pump Start Point in a Shopping Centre
A four-storey retail centre with two basement parking levels has an electric fire pump rated 500 gpm at 8 bar, a diesel standby pump, and a jockey pump rated 10 gpm. The sprinkler and hydrant systems share the pump room. During acceptance testing, the jockey pump cycles about every 90 seconds. The main electric pump starts only when header pressure falls to 5.8 bar. The contractor proposes raising the jockey stop pressure and lowering the main pump start pressure further so that the jockey runs less often. The contractor also asks the supervisor to sign the pump acceptance form because the main pump starts and delivers water. The owner is anxious to open the mall.
1. Evaluate the jockey pump cycling and the main pump start setting. What are the likely causes and why is the contractor's proposal unacceptable?
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Frequent jockey cycling usually means the system is losing pressure somewhere, or the jockey settings are too close together. Possible causes include a leaking check valve, a passing pressure-reducing valve, a leaking sprinkler test valve, trapped air, or a jockey stop pressure set so high that minor leakage immediately restarts it. The 90-second cycle is a symptom that must be investigated, not hidden.
The main pump start at 5.8 bar on an 8 bar rated pump is suspicious. A fire pump should start at a pressure that reflects a real drop from the jockey-maintained pressure, not so low that the system has already lost substantial pressure before the main pump runs. Lowering the start point further would delay the main pump and reduce available pressure during a fire. Raising the jockey stop pressure could increase cycling and stress the jockey pump.
The contractor's proposal treats the symptom. It is unacceptable because it could degrade fire protection and because the acceptance form would certify a system whose pressure-maintenance logic has not been explained. The supervisor should require a leak investigation, pressure-switch calibration, and a documented pump sequencing test.
2. Describe the acceptance tests and records you would require before signing the fire pump acceptance form.
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Before signing, the supervisor should require a witnessed sequence test and a flow test:
- Establish static pressure, then simulate a small drop to confirm jockey start and stop.
- Continue the drop to confirm the main electric pump starts at the correct set point, with the diesel standby available and its start sequence tested.
- Verify that the jockey stops when the main pump is running and that the main pump does not short-cycle.
- Perform a flow test at rated flow and at a higher flow condition where the installation allows, recording suction pressure, discharge pressure, flow, and pump speed.
- Check the pressure-switch settings against the approved design and record them.
- Confirm alarm and signal transmission to the fire alarm panel or monitoring point.
- Record the leak investigation and any repairs.
The acceptance form should not be signed merely because water flows. The record must show stable pressure maintenance, correct start sequence, and no unexplained cycling. If the contractor cannot explain the 90-second cycle, the supervisor should withhold acceptance of the pump room.
3. The contractor offers to disconnect the low-pressure alarm temporarily so the mall can open, promising to reconnect it after opening. How should the supervisor respond?
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The supervisor should refuse. Temporarily disabling a low-pressure alarm on a fire protection system creates a concealed impairment. If a fire occurs during the opening period, occupants and responders may rely on a system that is not being monitored. The promise to reconnect later is not an adequate control.
A proper response is to require the defect to be corrected before acceptance, or to approve a formally documented impairment procedure only if the authority having jurisdiction and the owner accept it, with fire watch or other compensating measures. The supervisor should not sign a false or misleading acceptance form.
Professionally, the supervisor's duty is to the safety of the building users and to the integrity of the certification, not to the opening schedule. The supervisor should issue a written nonconformance, notify the owner and, where required, the fire authority, and keep the acceptance pending until the alarm and pump sequencing are restored and tested.