Short answer: TS EN 12845+A2:2026 Clause 8.5.1 c) (EN p.44): all flow measuring devices shall have an error within ± 5 % of their maximum flow. Clause 8.5.1 d): where a calculated system is used, the capacity of the device is selected so that the system demand of both the most unfavourable and the most favourable area can be measured, and the device shall also have a measuring capacity of at least 140 % of the maximum demand flow.

Whether a sprinkler water supply really delivers the flow written in the calculation is known only by measurement. For this TS EN 12845+A2:2026 sets out the permanent measuring arrangements in Clause 8.5, the test procedure in Clause 8.6 and the periodic repetition in Clause 20. Source: TS EN 12845+A2:2026, Clauses 8.5 and 8.6, EN p.44-46 (TSE p.47-49).

1. Clause 8.5.1: General requirements for the measuring devices

Clause 8.5.1 (EN p.44) opens as follows: "Pressure and flow measuring devices shall be permanently provided for sprinkler systems in order to check compliance with Clause 7.3 and Clause 10, and the following shall apply:"

Item Requirement
a All the devices in a test unit shall be fit for purpose and installed in accordance with the manufacturer's instructions. The manufacturer's instructions shall include the minimum lengths of straight pipe upstream and downstream of the flow measuring device and the maximum flow velocity.
b The flow measuring device shall be installed in a frost proof area in a suitable position for easy access and reading.
c All flow measuring devices shall have an error within ± 5 % of their maximum flow. Where the device can be affected during transport, installation or continuous use, it shall be rechecked before the test results are used to assess the available flow.
d Where a calculated system is used, the capacity of the flow measuring device shall be selected so that the system demand for both the most unfavourable and the most favourable area can be measured. The device shall also have a measuring capacity of at least 140 % of the maximum demand flow (see Clause 7.3). Where the system demand is provided by more than one pump set operating in parallel, the capacity of the flow measuring device may be selected on the basis of the capacity of the largest pump; in that case the individual readings may be added provided the suction and delivery arrangement does not affect the result.
e The pressure readings to be used for the pressure and flow test curve shall be taken only with an accurate test gauge (± 1.6 %).
f At least three (3) pressure and flow readings shall be taken to establish a test curve. In addition, a pressure reading with no flow, that is the static pressure, shall be taken.

Where the device is installed depends on the type of water supply: where the water supply is an automatic pump set or sets, the flow measuring device is installed in the pump room (see Clause 8.5.2) and in that case Clause 8.5.1 does not apply. Where the water supply is not an automatic pump, the device is installed at the control valve sets (see Clause 8.5.3).

2. Clause 8.5.2: In the pump room

Clause 8.5.2 (EN p.45):

3. Clause 8.5.3: At the control valve sets

Where the water supply is not an automatic pump set or sets (Clause 8.5.3, EN p.45):

The 40 and 50 mm values in the last sentence apply only to this additional flow test valve; the general drain valve diameters are in Table 39.

4. Clause 8.6: Testing of the water supply

8.6.1 General (EN p.45):

The test arrangement specified in Clause 8.5.2 shall be used. Each supply to the installation shall be tested independently with all other supplies isolated. In both pre-calculated and fully calculated installations the water supply shall be tested at not less than the maximum demand flow of the installation.

8.6.2 Storage tank and pressure tank supplies (EN p.45-46): the stop valves controlling the flow from the water supply to the installation shall be fully opened. The operation of the automatic pump set shall be checked by reducing the system pressure. The flow shall be verified in accordance with Clause 7. The supply pressure measured at the 'C' gauge shall be verified as being at least the relevant value specified in Clause 7.

8.6.3 Town main, booster pump, elevated private reservoir and gravity tank supplies (EN p.46): the stop valves controlling the flow from the supply to the installation shall be fully opened. The operation of the automatic pump set shall be checked by reducing the system pressure. The drain and test valve shall be adjusted to give the flow specified in Clause 7. When the flow has stabilized, the supply pressure measured at the 'C' gauge shall be verified as being at least the relevant value in Clause 7.

For a boosted town main, Clause 10.7.4 (EN p.63) defines a further test: a test is carried out to demonstrate that the unboosted supply provides the maximum demand flow plus 20 % at a pressure of at least 0.5 bar measured at the pump inlet. This test is carried out at the time of maximum demand on the main.

5. Pressure gauges and test valves

Pressure gauges (Clause 15.7, EN p.109)

Test valves (Clause 15.5, EN p.108-109)

15.5.1 Alarm and pump set starting test valves: test valves of 15 mm shall be suitably fitted to test the following:

15.5.2 Remote test valves: a test arrangement shall be provided comprising a test valve connected at the hydraulically most remote position of a distribution pipe giving a flow equivalent to the discharge of a single sprinkler, together with the associated fittings and pipework.

Drain valves (Clause 15.4, Table 39, EN p.107-108)

Drain valves are fitted at the following points: a) immediately downstream of the control valve set or of any stop valve downstream of it; b) immediately downstream of any subsidiary alarm valve; c) immediately downstream of any subsidiary stop valve; d) between a dry pipe or subsidiary control valve set and any subsidiary stop valve installed for testing purposes; e) on every pipe that cannot be drained from another drain valve, excluding drop pipes to single sprinklers in a wet installation. The valves are fitted at the lower end of the pipework; the outlet is not more than 3 m above floor level and is provided with a suitable plug.

Valve draining principally Minimum valve and pipe diameter (mm)
LH installation 40
OH or HHP or HHS installation 50
Subsidiary installation 50
A zone 50
Trapped distribution pipes, diameter ≤ 80 mm 25
Trapped distribution pipes, diameter > 80 mm 40
Trapped range pipes 25
Trapped pipework between a dry or subsidiary alarm valve and a subsidiary stop valve installed for testing purposes 15

Source: Table 39, Clause 15.4, EN p.108 (TSE p.111).

6. Commissioning tests (Clause 19)

Test Requirement Source
Dry pipe installation, pneumatic A pressure of at least 2.5 bar for at least 24 hours; any leakage causing a pressure loss of more than 0.15 bar in 24 hours is rectified Clause 19.1.1.1, EN p.117
All pipework, hydrostatic For at least 2 hours at a pressure of at least 15 bar, or 1.5 times the maximum pressure to which the system will be subjected, whichever is greater, both measured at the installation control valves Clause 19.1.1.2, EN p.117
Equipment The system is tested once as specified in Clauses 20.2.2 and 20.3.2 (that is, the weekly and quarterly routine tests) and any faults found are rectified Clause 19.1.2, EN p.117
Water supplies Tested once as specified in Clause 8.6; diesel engine driven pumps are tested in accordance with Clause 20.2.2.5 Clause 19.1.3, EN p.117

Clause 19.1.1.2 also warns that no system component shall be subjected to a pressure higher than that recommended by the supplier. Clause 19.2 (EN p.118) covers the completion certificate and the documentation: the installer shall give the user a completion certificate stating that the system complies with all the relevant requirements of the standard or detailing the deviations, together with a complete set of operating instructions and the "as-built" design documents.

7. Periodic tests

Interval Test Source
Weekly (≤ 7 days) All water and air pressure gauge readings are checked and recorded; in dry, alternate and pre-action installations the pipe pressure shall not fall by more than 1.0 bar per week. All water levels and the correct position of all main stop valves are checked Clauses 20.2.2.1, 20.2.2.2, EN p.119
Weekly Every water motor alarm is sounded for at least 30 seconds Clause 20.2.2.3, EN p.119
Weekly Automatic pump set starting test: on diesels the fuel and oil levels; simulation of automatic operation by reducing the water pressure on the starting device; checking and recording of the starting pressure when the pump starts; on diesels the oil pressure and the cooling water flow in open circuit cooling Clause 20.2.2.4, EN p.119
Quarterly (≤ 13 weeks) Each water supply is tested with each control valve set in the system; where fitted, the pump or pumps shall start automatically and the supply pressure at the relevant flow shall not be less than the appropriate value in accordance with Clause 10 (recognizing the modifications required by 20.3.2.2) Clause 20.3.2.5, EN p.121
Quarterly All stop valves controlling the flow of water to the sprinklers are operated to ensure that they are in working order and securely refixed in the correct mode. This covers those at all water supplies, at the alarm valve or valves and all zone or other subsidiary stop valves Clause 20.3.2.7, EN p.121
Quarterly The flow alarms (flow switches and/or pressure switches) are checked for correct operation Clause 20.3.2.8, EN p.121
Annually (≤ 12 months) Each water supply pump set is tested at the full load condition by means of the test line connection coupled to the delivery branch downstream of the pump set outlet non-return valve, and shall give the pressure and flow values stated on the nameplate. Appropriate allowances are made for pressure losses in the supply pipe and valves between the source and each control valve set Clause 20.3.4.2.1, EN p.122
Annually Where no pump is installed: each water supply is tested at the full load condition by means of the test line connection coupled to the water supply upstream of the control valve set, and shall meet the required flow and pressure values Clause 20.3.4.2.2, EN p.122
Annually The diesel failed-to-start alarm is tested; immediately after the test the engine is started using the manual starting system Clause 20.3.4.3, EN p.122
Annually The float valves on the water storage tanks are checked Clause 20.3.4.4, EN p.122
Annually The pump set suction strainers, settling chamber and their screens are inspected and cleaned as necessary Clause 20.3.4.5, EN p.122
Annually The system is periodically inspected by a qualified person (see Annex Q); the inspection report assesses whether the system complies with the standard with regard to maintenance, operation and adequacy for the risk, and a list of deviations is issued Clause 21, EN p.123

The recording of all inspections is subject to Clause 20.3.1.2 (EN p.120): "A signed and dated inspection report shall be given to the user; the report shall include information on any correction made or required and details of any external factors (for example weather conditions) which may have affected the results."

8. Summary of the test sequence

  1. Verification of the arrangement: position and capacity of the flow meter (± 5 %, ≥ 140 %), class of the pressure gauge (± 1.6 %), positions of the upstream and downstream gauges, arrangement for disposal of the test water.
  2. Isolation: all supplies other than the one to be tested are isolated (Clause 8.6.1).
  3. Static reading: the pressure is read with no flow (Clause 8.5.1 f).
  4. At least three P/Q points: at least three pressure and flow readings are taken for the test curve (Clause 8.5.1 f).
  5. Verification at the maximum demand flow: the supply is tested at not less than the maximum demand flow of the installation (Clause 8.6.1); the pressure at the 'C' gauge shall not be less than the value in Clause 7 (Clauses 8.6.2 and 8.6.3).
  6. Automatic start: the starting of the pump set is checked by reducing the system pressure (Clauses 8.6.2 and 8.6.3).
  7. Record: a signed and dated report is issued (Clause 20.3.1.2).

Frequently Asked Questions

What accuracy and capacity are required of the flow measuring device?

TS EN 12845+A2:2026 Clause 8.5.1 c) (EN p.44): all flow measuring devices shall have an error within ± 5 % of their maximum flow. Clause 8.5.1 d): where a calculated system is used, the capacity of the device is selected so that the system demand of both the most unfavourable and the most favourable area can be measured, and the device shall also have a measuring capacity of at least 140 % of the maximum demand flow.

How many points are read for the test curve?

Clause 8.5.1 f) (EN p.45): at least three pressure and flow readings shall be taken to establish a test curve. In addition, a pressure reading with no flow, that is the static pressure, shall be taken. Under Clause 8.5.1 e), the pressure readings to be used for the pressure and flow test curve shall be taken only with an accurate test gauge (± 1.6 %).

How are the water supplies tested?

Clause 8.6.1 (EN p.45): the test arrangement specified in Clause 8.5.2 is used. Each supply to the installation shall be tested independently with all other supplies isolated. In both pre-calculated and fully calculated installations the water supply is tested at not less than the maximum demand flow of the installation.

How is the annual full load pump test carried out?

Clause 20.3.4.2.1 (EN p.122): each water supply pump set in the installation is tested at the full load condition by means of the test line connection coupled to the pump set delivery branch downstream of the pump set outlet non-return valve, and shall give the pressure and flow values stated on the nameplate. Appropriate allowances are made for pressure losses in the supply pipe and valves between the source and each control valve set.

What are the drain valve diameters?

Table 39 (Clause 15.4, EN p.108): LH installation 40 mm; OH, HHP or HHS installation 50 mm; subsidiary installation 50 mm; a zone 50 mm; trapped distribution pipes 25 mm where the diameter is ≤ 80 mm and 40 mm where it is > 80 mm; trapped range pipes 25 mm; trapped pipework between a dry or subsidiary alarm valve and a subsidiary stop valve installed for testing purposes 15 mm.

What is done in the weekly pump starting test?

Clause 20.2.2.4 (EN p.119): on diesel engines the fuel and engine lubricating oil levels are checked; the automatic starting condition is simulated by reducing the water pressure on the starting device; the starting pressure is checked and recorded when the pump set starts; on diesel pumps the oil pressure and the cooling water flow in open circuit cooling systems are checked. Clause 20.2.2.1 requires this routine at intervals of not more than 7 days.

References

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Standards & References

TS EN 12845+A2:2026 (EN 12845:2015+A2:2026) Fixed firefighting systems — Automatic sprinkler systems — Design, installation and maintenance; TS EN 12845-2:2025 (EN 12845-2:2024) ESFR and CMSA sprinkler systems. Every figure in this article is taken from the published standard text; clause, table and page references are listed under References. General information only, not a substitute for the standard or for a design review.

FS

Fatih Selvi

Mechanical engineer and software developer with field experience in MEP and fire protection, working actively with NFPA, FM Global and BS EN 12845 on site projects.