EN 12845 Commissioning, Hydrostatic Testing and Certification

This is the gate through which a sprinkler system earns its "working" stamp: hydrostatic test, flushing, alarm proving, documentation and the commissioning certificate. A certificate issued with gaps in it will come back at you across a claims table ten years later.

Ten days before an automotive parts warehouse opened, the word was that the hydrostatic test had passed and the acceptance record had been signed. Six months later a spot check found that the alarm valve flow indicator had never been fitted — yet the certificate carried a tick and a signature against it. That signature will be argued over in an insurance file in year eleven. EN 12845 Clause 19 forces commissioning to be evidenced on site, not on paper.

Clause 19 — the commissioning sequence

Flushing

Once the hydraulic calculation is complete and the pipework is installed — but before the sprinkler heads go on — the whole system is flushed. Velocity must be at least 5 m/s or the design flow, whichever is greater. Continue until the water is at town main quality: visibly clear and free of sediment. Flushing clears weld slag, installation grit and rusty water.

Hydrostatic pressure test

The pipework is filled with the ends capped, air is vented, and pressure is raised slowly:

• Above-ground pipework: 1.5 times working pressure or 15 bar, whichever is greater, held for 2 hours.
• Underground pipework: 15 bar, held for 6 hours.
• There must be no pressure drop. Every joint, weld and flange is inspected visually.

If pressure does fall: air may be trapped (vent again), there may be a leak (locate with soapy water or compressed air), or thermal expansion may be at work (wait for ambient temperature to stabilise).

Alarm and functional tests

• Each zone opened from its alarm test connection — does the flow alarm operate?
• Water motor gong audible, where fitted
• Automatic pump start on pressure drop
• Pump flow test, checking three points on the curve
• Diesel engine dry-running limits and manual start
• Fire service and central monitoring connection, with a test signal
• Are the stop valves supervised in the open position?

The commissioning certificate

The certificate is not a single sheet; it is a documentation file. The minimum content:

• Facility details: address, occupancy type, occupier
• Designer, installing contractor, commissioning engineer
• Hazard class (LH, OH1–4, HHP1–4, HHS1–4) and storage type (ST1–ST6)
• Hydraulic calculation summary: density, area of operation, flow, pressure
• Water supply: type, capacity, duration, pump curve
• Sprinkler schedule: K-factor, temperature rating, type, quantity
• Pipe material, diameters and protective treatment
• Test results: flushing, hydrostatic, alarms, pumps
• A list of deviations, with the approvals against them
• As-built drawing references
• Signatures: designer, installer, client and, where involved, insurer

Field error — hydrostatic passed, sprinklers blocked

At a textile warehouse the hydrostatic test passed — on paper. Three months later, during the first real alarm, three sprinkler orifices were found blocked with sand and weld slag. Looking back, flushing had never been carried out; only the hydrostatic test had been recorded. The certificate was false. The designer faced litigation, the installer went into insolvency, and the client was left with the loss. If the flushing clause is skipped, the hydrostatic clause alone guarantees nothing.

Practical test choreography

Step	Activity	Duration
1	Pipework complete, sprinkler heads not yet fitted	—
2	Flushing — open ends, water at 5 m/s	5–15 min per zone
3	Sprinkler heads fitted	1–3 days
4	Air venting and slow pressurisation	30–60 min
5	Hydrostatic test at 15 bar or 1.5 × working	2 hour hold
6	Depressurise, system normalised	30 min
7	Alarm and functional tests	4–8 hours
8	Pump flow and diesel tests	1 day
9	As-built drawings and certificate file	1–2 weeks
10	Handover meeting and logbook opened	1 day

Link to Annex J — the system is out of service during testing

During commissioning tests the sprinkler protection is not actually working. Under the Annex J impairment provisions:

• Hot work — welding, grinding, naked flame — is prohibited
• No combustible material may be added
• Fire watch rounds every hour
• Temporary hoses and extinguishers positioned
• Fire service and insurer notified

When testing finishes, stop valves are returned to the locked-open position, alarms are normalised, and the logbook records the exact out-of-service and back-in-service times.

Comparison with NFPA 13

NFPA 13 and 24 call for a hydrostatic test at 200 psi (about 13.8 bar) or 50 psi above working pressure, whichever is greater, held for 2 hours. EN 12845 requires 15 bar or 1.5 times working pressure. In practice the figures are close. NFPA also tabulates flushing velocity by pipe size, typically at least 6 m/s, on the same principle. Instead of a certificate, NFPA uses the Contractor's Material and Test Certificate template, whose content overlaps the EN 12845 certificate by about 90 %.

Link to Turkish regulation

BYKHY requires a fire safety file for the occupancy permit, and the sprinkler certificate is the core of that file. A missing or defective certificate returns the fire service compliance report marked "conditionally compliant", and the facility cannot open. Missing as-built drawings or hydraulic calculations produce the same result. For the client, commissioning day is not the day the insurance starts — it is the day the occupancy permit becomes reachable.

Quick check list

• Flushing at 5 m/s, discharge running clear.
• Hydrostatic at 15 bar or 1.5 × working, 2 hours, zero drop.
• All zone alarm tests recorded.
• Pump flow curve verified at three points.
• Diesel manual and automatic start both working.
• Fire service connection receiving the signal.
• As-built drawings, hydraulic calculation and equipment schedule complete.
• Certificate delivered with every signature in place.
• Logbook opened and the first weekly routine scheduled.

Frequently Asked Questions

What pressure is the hydrostatic test carried out at?

1.5 times working pressure or 15 bar, whichever is greater, held for 2 hours above ground. Underground pipework is tested at 15 bar for 6 hours.

Why is flushing done before the heads are fitted?

Because weld slag, installation grit and rust would otherwise block the sprinkler orifices. Flush at 5 m/s until the discharge runs visibly clear.

What must the commissioning certificate contain?

Facility and party details, hazard classification, hydraulic summary, water supply and pump data, the sprinkler and pipe schedules, all test results, a deviation list, as-built references and signatures.

Is the building protected during commissioning tests?

No. The system is effectively out of service, so the impairment measures apply: no hot work, no added combustibles, hourly fire watches, temporary hoses and notification of the insurer.

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