On the subject of diesel engine driven pump sets, TS EN 12845+A2:2026 contains a structural change compared with earlier editions: Clause 10.9 now consists of three short subclauses and hands the technical requirements over to EN 17451. This article shows what A2:2026 actually says, gathers the general Clause 10 provisions that continue to apply to a diesel pump set, and gives the diesel tests on the maintenance side with their source. Source: TS EN 12845+A2:2026, Clauses 10 and 20.
The full content of Clause 10.9 in A2:2026
10.9.1 General (TS p.68 / EN p.65)
Diesel driven pump sets and ancillaries shall be in accordance with EN 17451. There shall be enough fresh air available in the pump room at all times to keep the diesel pump set running within the manufacturer specified limits and EN 17451.
10.9.2 Starter alarm indication (TS p.69 / EN p.66)
The following conditions shall each be indicated both locally and at a responsibly manned location (see Annex I) by warning lights: a) pump running; b) start failure; c) common faults; d) automatic mode off.
10.9.3 Site commissioning test (TS p.69 / EN p.66)
Site commissioning test shall be performed in accordance with EN 17451.
That is the whole of Clause 10.9. There are no subclauses 10.9.4, 10.9.5, 10.9.6, 10.9.7, 10.9.8, 10.9.9, 10.9.11 or 10.9.13 in the text of A2:2026. Provisions such as fuel tank capacity (running time in hours), exhaust arrangements, the air filter, the starting attempt sequence (the number and duration of attempts), the number and standard of battery sets, and the cell voltage of the charger are therefore not to be looked for in this standard.
One cross-reference is left dangling in the text: Clause 20.3.4.3 (TS p.125 / EN p.122) states that in the yearly routine the failure to start alarm shall be tested "in accordance with 10.9.7.2", but there is no clause 10.9.7.2 in A2:2026. The second sentence of the same clause remains applicable: immediately after this test the engine shall be started using the manual starting system.
The European foreword of the standard gives the reason for the change (TS p.13 / EN p.10): compared with EN 12845:2015+A1:2019, technical changes have been made in order to integrate the references to EN 17451, EN 12845-2 and EN 12845-3 and their use into this document.
Other references to EN 17451
EN 17451 appears in several other places in the text of A2:2026:
| Clause | Reference | Page |
|---|---|---|
| 4.4.4.4 | Pump set documentation shall be provided in accordance with EN 17451 | TS p.31 / EN p.28 |
| 10.1 | Water supplies consisting of pumps shall conform to EN 17451 | TS p.60 / EN p.57 |
| 10.6.2.1 | The available NPSH in the suction pipe shall exceed the required NPSH by at least 1 m at the maximum pump set flow shown in Table 14, according to EN 17451 | TS p.62 / EN p.59 |
| 18.2.5.2 | On fully calculated installations the installer data in accordance with EN 17451 shall be displayed at the pump | TS p.119 / EN p.116 |
| Annex P | Three 50 % pump sets in accordance with EN 17451 are recommended for the ESFR water supply | TS p.167 / EN p.164 |
Provisions that continue to apply to a diesel pump set
Although Clause 10.9 has been narrowed, the general provisions of Clause 10 cover diesel sets as well, as "pump sets".
10.2 Multiple pump set arrangements (TS p.60 / EN p.57)
- Pump sets shall have compatible characteristic curves and be capable of operating in parallel at all possible flow rates.
- Where two pumps are installed, each one shall be capable independently of providing the specified flows and pressures.
- Where three pumps are installed, each pump shall be capable of providing at least 50 % of the specified flow at the specified pressure.
- Where more than one pump is installed in a superior or duplicate water supply, no more than one shall be driven by an electric motor.
In practice the last item means that in a superior or duplicate water supply with two or more pumps, at least one pump has to be diesel (or otherwise non-electrically) driven.
10.3 Compartments for pump sets (TS p.60-61 / EN p.57-58)
10.3.1 General: Pump sets shall be housed in a compartment having a fire resistance of no less than 60 min, used for no other purpose than fire protection. It shall be one of the following (in order of preference):
- a) a separate building;
- b) a building adjacent to a sprinkler protected building with direct access from outside;
- c) a compartment within a sprinkler protected building with direct access from outside.
10.3.2 Sprinkler protection: Compartments for pump sets shall be sprinkler protected. Where the pump compartment is separate, it might be impractical to provide sprinkler protection from the control valve sets in the premises; in that case protection might be provided from the nearest accessible point on the downstream side of the outlet non-return valve of the pump, via a subsidiary stop valve secured in the open position, together with a water flow detector in accordance with EN 12259-5 to provide visible and audible indication of the operation of the sprinklers. A 15 mm nominal diameter drain and test valve shall be fitted downstream of the flow alarm to permit a practical test of the alarm system.
10.3.3 Temperature: The pump set compartment shall be maintained at or above the following temperature:
| Pump type | Minimum compartment temperature |
|---|---|
| Electric driven pump sets | 4 °C |
| Diesel driven pump sets | 10 °C |
10.3.4 Ventilation: Compartments for diesel pump sets shall be provided with adequate ventilation in accordance with the supplier's recommendations.
10.4 Maximum temperature of water supply (TS p.61 / EN p.58)
The water supply temperature shall not exceed 40 °C. Where submersible pump sets are utilized, the water temperature shall not exceed 25 °C unless the suitability of the motor has been proven for temperatures up to 40 °C.
10.5 Valves and accessories (TS p.61 / EN p.58)
A stop valve shall be fitted in the pump suction pipe unless the maximum water level is lower than the pump. A non-return valve and a stop valve shall be fitted in the delivery pipe of each pump. Any taper pipe fitted to the pump outlet shall expand in the direction of flow at an angle not exceeding 20°.
The same clause contains a note specific to diesel sets: a continuous flow of water sufficient to prevent the pump overheating while running against a closed valve shall be provided, and this flow shall be taken into account in the system hydraulic calculation and in the selection of the pump. The outlet shall be clearly visible and, where there is more than one pump, the outlets shall be separate. Diesel engine cooling circuits generally use the same water; however, where additional water is used this shall also be taken into account.
10.6 Suction conditions (TS p.62-63 / EN p.59-60)
10.6.1: Wherever possible, horizontal centrifugal pump sets shall be installed with a positive suction head: at least two thirds of the effective capacity of the suction tank shall be above the level of the pump centre line, and the pump centre line shall be no more than 2 m above the low water level of the suction tank (level X in 9.3.5).
10.6.2.2 Positive head: The diameter of the suction pipe shall be no less than 65 mm and shall be such that a velocity of 1.8 m/s is not exceeded when the pump is operating at maximum demand flow.
10.6.2.3 Suction lift: The diameter of the suction pipe shall be no less than 80 mm and a velocity of 1.5 m/s shall not be exceeded at maximum demand flow. Where more than one pump set is installed, the suction pipes shall not be interconnected. The height from the low water level to the centre line of the pump shall not exceed 3.2 m. A foot valve shall be fitted at the lowest point on the suction pipe.
10.6.2.4 Pump priming: Each pump set shall be fitted with a separate automatic priming arrangement. The arrangement shall consist of a tank situated at a higher level than the pump, with a pipe connection sloping from the tank to the delivery side of the pump; a non-return valve shall be fitted to this connection. Should the water level in the tank fall to 2/3 of the normal level, the pump shall start; alternatively, an alarm shall be sent to a permanently attended location ensuring immediate action.
Table 15 Pump set priming tank capacity and pipe size (TS p.65 / EN p.62):
| Hazard class | Minimum tank capacity (litres) | Minimum priming pipe diameter (mm) |
|---|---|---|
| LH | 100 | 25 |
| OH, HHP and HHS | 500 | 50 |
Monitoring and marking
Annex I, Table I.1 (TS p.158 / EN p.155) gives the alarm types for the diesel pump set (the reference is to Clause 10.9.2):
| Alarm | Type |
|---|---|
| Automatic mode off | B |
| Start failure | B |
| Running | A |
| Common fault | B |
Annex I, I.2 Alarm levels (TS p.159 / EN p.156): signals from water flow alarms and/or alarm valves shall be indicated as a fire alarm (level A in Table I.1). Depending on local conditions, a signal indicating that the sprinkler pump set is running might alternatively be treated as a fault alarm. Technical faults such as a loss of power that could prevent the system operating correctly in a fire shall be indicated as a fault alarm (level B).
Annex H, H.2.6 Electrical power (TS p.157 / EN p.154): the power supply to electric pump sets or other critical electrical equipment shall be monitored, and an indication shall be given if one or more phases fail at any point in the main supply, the control circuit or the electric or diesel pump set control unit. H.2.4 (TS p.156 / EN p.153) requires an indication before the fuel level falls by more than 25 % of the nominal fill level. H.2.7 (TS p.157 / EN p.154) requires the minimum temperature of the sprinkler valve and pump rooms to be monitored.
Clause 18.2.6.2 (TS p.119-120 / EN p.116-117): the alarms specified in 10.8.5.1 and 10.9.2 shall be marked, both at the pump set controller and at the responsibly manned location, as appropriate: 'diesel fire pump starter switched off', 'diesel fire pump failure to start', 'pump running', 'diesel controller fault'. The manually operated shut-down mechanism shall be labelled 'SPRINKLER PUMP SHUT-OFF'.
Clause 18.2.5.1 (TS p.119 / EN p.116): a nameplate shall be fixed to each suction or booster pump giving the outlet pressure in bar at the inlet condition and flow value specified in Table 16, the corresponding nominal speed and the flow in litres per minute, and the maximum power absorbed at any flow value at the relevant speed.
For comparison: the 15 seconds for an electric pump set
A point that is often confused: the 15 second requirement is for the electric pump, not the diesel. Clause 10.8.1.3 (TS p.67 / EN p.64), under the heading "10.8 Electrically driven pump sets", states that "after starting, the pump set shall be operating at its rated capacity within 15 s". There is no run-up time provision for the diesel pump in Clause 10.9 of A2:2026.
The monitoring list for the electric set is separate too. Clause 10.8.5.1 (TS p.68 / EN p.65): power available to the motor and, where AC, on all three phases; pump on demand; pump running; start failure. 10.8.5.2: all monitored conditions shall be visually indicated individually in the pump room; pump running and a fault alarm shall also be indicated audibly and visually at a location permanently attended by responsible personnel.
Maintenance: the tests belonging to the diesel pump
| Period | Clause | Content | Page |
|---|---|---|---|
| Weekly | 20.2.2.4 | The fuel and engine lubricating oil levels in diesel engines are checked; the water pressure on the starting device is reduced, simulating automatic starting; when the pump starts, the starting pressure is checked and recorded; on diesel pumps the oil pressure and the flow of cooling water through open circuit cooling systems are checked | TS p.122 / EN p.119 |
| Weekly | 20.2.2.5 | The engine is run for 20 min (or for the time recommended by the supplier), stopped and immediately restarted using the manual start test button; the water level in the primary circuit of closed circuit cooling is checked; oil pressure, engine temperatures and coolant flow are monitored throughout the test; the oil hoses are checked; a general inspection is made for leakage of fuel, coolant or exhaust fumes | TS p.122-123 / EN p.119-120 |
| Monthly | 20.2.3 | The electrolyte level and density of all lead acid cells (including diesel engine starter batteries and those for control panel power supplies); if the density is low the battery charger is checked first and, if it is working normally, the battery is replaced | TS p.123 / EN p.120 |
| Quarterly | 20.3.2.6 | Secondary electrical supplies from diesel generators are checked for satisfactory operation | TS p.124 / EN p.121 |
| Yearly | 20.3.4.2.1 | Each water supply pump set in the installation shall be tested at full load condition by means of the test line connection on the delivery leg downstream of the pump set outlet non-return valve, and shall give the pressure/flow values specified on the nameplate; appropriate allowances shall be made for the pressure losses in the supply pipe and valves between the source and each control valve set | TS p.124-125 / EN p.121-122 |
| Yearly | 20.3.4.3 | Test of the diesel engine failure to start alarm; immediately afterwards the engine shall be started using the manual starting system | TS p.125 / EN p.122 |
| Yearly | 20.3.4.5 | The pump set suction strainers, the settling chamber and its screens shall be inspected at least once a year and cleaned as necessary | TS p.125 / EN p.122 |
The same tests are used at commissioning: Clause 19.1.3 (TS p.120 / EN p.117) requires the water supplies to be tested once in accordance with 8.6 and the diesel engine driven pumps to be tested as specified in 20.2.2.5.
Field note
Clause 10.9 of A2:2026 has not been emptied but redirected: the internal requirements of the diesel set are to be found in EN 17451, while the system side requirements (compartment, temperature, ventilation, suction, priming, monitoring, marking, periodic testing) stay in EN 12845. A specification whose diesel pump clause refers only to EN 12845 now leaves out most of the technical requirements. (This paragraph is engineering commentary.)
Frequently Asked Questions
Which clause applies to diesel pump sets in A2:2026?
TS EN 12845+A2:2026 Clause 10.9 consists of three subclauses. 10.9.1 General (TS p.68 / EN p.65): diesel driven pump sets and ancillaries shall be in accordance with EN 17451; there shall be enough fresh air available in the pump room at all times to keep the diesel pump set running within the manufacturer specified limits and EN 17451. 10.9.2 Starter alarm indication (TS p.69 / EN p.66). 10.9.3 Site commissioning test: it shall be performed in accordance with EN 17451. There is no 10.9.4 or any later subclause in A2:2026.
What is the minimum temperature of a diesel pump room?
Clause 10.3.3 (TS p.61 / EN p.58): the pump set compartment shall be maintained at or above 4 °C for electric driven pump sets and 10 °C for diesel driven pump sets. Clause 10.3.4 additionally requires compartments for diesel pump sets to be provided with adequate ventilation in accordance with the supplier's recommendations.
Which four conditions are indicated on a diesel pump set?
Clause 10.9.2 (TS p.69 / EN p.66): the following conditions shall each be indicated both locally and at a responsibly manned location (see Annex I) by warning lights: a) pump running; b) start failure; c) common faults; d) automatic mode off. Table I.1 of Annex I (TS p.158 / EN p.155) treats the 'running' signal as a type A alarm and the other three as type B.
Does the 15 second requirement apply to the diesel pump?
No, it applies to the electric pump. Clause 10.8.1.3 (TS p.67 / EN p.64): 'After starting, the pump set shall be operating at its rated capacity within 15 s.' That clause sits under the heading 10.8 Electrically driven pump sets. Clause 10.9 of A2:2026 contains no run-up time provision for the diesel pump; the subject has been handed over to EN 17451.
What flow must each pump deliver where three pumps are installed?
Clause 10.2 (TS p.60 / EN p.57): pump sets shall have compatible characteristic curves and be capable of operating in parallel at all possible flow rates. Where two pumps are installed, each one shall be capable independently of providing the specified flows and pressures. Where three pumps are installed, each pump shall be capable of providing at least 50 % of the specified flow at the specified pressure. Where more than one pump is installed in a superior or duplicate water supply, no more than one shall be driven by an electric motor.
References
- TS EN 12845+A2:2026 European foreword, integration of EN 17451 / EN 12845-2 / EN 12845-3 (TS p.13 / EN p.10)
- TS EN 12845+A2:2026 Clause 4.4.4.4 Automatic pump set documentation (TS p.31 / EN p.28)
- TS EN 12845+A2:2026 Clauses 10.1, 10.2, 10.3.1 (TS p.60 / EN p.57)
- TS EN 12845+A2:2026 Clauses 10.3.2, 10.3.3, 10.3.4, 10.4, 10.5 (TS p.61 / EN p.58)
- TS EN 12845+A2:2026 Clauses 10.6.1, 10.6.2.1, Table 14, 10.6.2.2 (TS p.62 / EN p.59)
- TS EN 12845+A2:2026 Clauses 10.6.2.3, 10.6.2.4 (TS p.63 / EN p.60)
- TS EN 12845+A2:2026 Table 15 Priming tank (TS p.65 / EN p.62)
- TS EN 12845+A2:2026 Clause 10.8.1.3 (TS p.67 / EN p.64)
- TS EN 12845+A2:2026 Clauses 10.8.5.1, 10.8.5.2, 10.9.1 (TS p.68 / EN p.65)
- TS EN 12845+A2:2026 Clauses 10.9.2, 10.9.3 (TS p.69 / EN p.66)
- TS EN 12845+A2:2026 Clauses 18.2.5.1, 18.2.5.2, 18.2.6.2 (TS p.119-120 / EN p.116-117)
- TS EN 12845+A2:2026 Clause 19.1.3 (TS p.120 / EN p.117)
- TS EN 12845+A2:2026 Clauses 20.2.2.4, 20.2.2.5, 20.2.3 (TS p.122-123 / EN p.119-120)
- TS EN 12845+A2:2026 Clauses 20.3.2.6, 20.3.4.2.1 (TS p.124 / EN p.121)
- TS EN 12845+A2:2026 Clauses 20.3.4.3, 20.3.4.5 (TS p.125 / EN p.122)
- TS EN 12845+A2:2026 Annex H, H.2.4 (TS p.156 / EN p.153), H.2.6 and H.2.7 (TS p.157 / EN p.154)
- TS EN 12845+A2:2026 Annex I, Table I.1 (TS p.158 / EN p.155), I.2 (TS p.159 / EN p.156)
- TS EN 12845+A2:2026 Annex P (TS p.167 / EN p.164)
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Download MEP Calc on the App StoreTS 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.