Commissioning is where the defects a system will carry for its whole life are set. A mistake made at this stage shows up in a fire ten years later. The twenty below appear again and again at acceptance testing.
Installation and cleanliness
- No flushing. Weld slag, installation debris and soil stay in the pipe, becoming both a blockage and a seed for corrosion.
- Flushing at inadequate flow. Water moving slowly does not carry sediment; the flush looks done but achieves nothing.
- Missing hangers and supports. Especially on risers and large diameters; pipe that moves under water hammer fatigues its joints.
- Seismic bracing requirements skipped. Not installed where required.
- Sprinkler protective caps left on. Caps fitted to protect against paint and dust are never removed.
- Painted sprinklers. Paint changes the thermal element's response; a painted head must be replaced.
Testing and settings
- Hydrostatic test held short on duration or pressure.
- No pump flow test. Starting the pump and reading a pressure is not a test; churn, the rated point and the 150% flow point must be measured.
- Pump curve not compared with the design. Values are recorded but never assessed against the design curve.
- Wrong jockey pump setting. Causing the main pump to run unnecessarily or to start too late.
- Automatic shutdown left enabled. A fire pump must be stopped manually.
- Dry system trip time not measured.
- No flow trial from the most remote inspector's test valve.
Alarms and integration
- Flow switch delay not set. Producing false alarms or late alarms.
- Tamper switches not wired to the panel. Physically fitted but left unconnected.
- Alarm transmission to the receiving centre not verified. The alarm shows at the panel but goes no further.
- No scenario testing. Smoke control, lift recall, door release and the public address chain never tried end to end.
Labelling and documentation
- Incomplete valve labelling. No record of which valve feeds which zone.
- Hydraulic design plate not fitted. Design density, area and required pressure must be displayed on the system.
- As-built and O&M file not handed over. Calculations, equipment certificates, test records and maintenance instructions delivered incomplete.
The most expensive mistake is the first one. A system commissioned without flushing looks fine for the first few years; sediment and corrosion appear within a few more, and by then the fix is pipe renewal. Flushing is the cheapest, highest-return step in commissioning.
What the handover file must contain
- The approved design report and hydraulic calculation.
- As-built drawings (floor plans, riser diagram, valve arrangement).
- Equipment schedule with approval and listing certificates.
- Flushing, hydrostatic test and flow test records.
- The pump performance curve and acceptance test report.
- Alarm and scenario test records.
- Maintenance instructions and the periodic test schedule.
- Spare parts list and the contents of the spare sprinkler cabinet.
Last-day check before acceptance
- Are all control valves open and locked or monitored?
- Have sprinkler protective caps been removed?
- Are there any painted or damaged heads?
- Is the hydraulic design plate fitted?
- Are the spare sprinkler cabinet and wrench in place?
- Are the system schematic and contact list in the pump room?
- Is test line discharge resolved?
- Have all impairment records been closed out?
Frequently Asked Questions
What is the most expensive commissioning mistake?
No flushing, or flushing at inadequate flow. Remaining sediment and slag cause both blockage and corrosion, and within a few years the fix extends to pipe renewal.
How should a pump be tested?
Starting it and reading a pressure is not enough. Churn pressure, the rated point and the 150% flow point must be measured and the measured curve compared with the design curve.
Can a painted sprinkler be used?
No. Paint changes the thermal element's response and a painted head must be replaced. Protective caps must likewise be removed.
What must the handover file contain?
Design report and hydraulic calculation, as-built drawings, equipment and approval certificates, flushing/hydrostatic/flow test records, the pump curve, scenario test records, maintenance instructions and the spare parts list.
SprinkCalc — Fire Sprinkler Design Across Three Standards
SprinkCalc covers hazard classification, design density and area, K-factor selection, water demand and hydraulic calculations for NFPA 13, FM Global and BS EN 12845 in a single iOS app, and exports a professional PDF report.
Download SprinkCalc on the App Store
MEP Calc — 86+ Engineering Calculators
MEP Calc bundles 86+ engineering modules in one iOS app: 21 fire calculations plus heating, cooling, HVAC, plumbing, steam and natural gas.
Download MEP Calc on the App StoreNFPA 13 (2025) · NFPA 25 · BS EN 12845:2015+A1:2019 · FM Global DS 2-0, DS 8-9. The findings here are typical defect patterns defined in the standards and survey guidance, not an account of events at any particular site.