Source: TS EN 12845+A2:2026 (EN 12845:2015+A2:2026), Clauses 8.4, 10.3, 10.4, 10.5, 10.6 and Clause 20.3.4.5.
The most common mistake in pump room projects is to take figures that are customary on site for provisions of the standard. EN 12845 gives numbers for the pump compartment on only a few subjects: fire resistance, temperature, sprinkler protection, suction geometry and priming tank size. On headings such as ventilation flow rate, drainage size, lighting level and service clearance the standard gives no number; this article separates where each figure comes from and which of them lie outside the standard.
The compartment itself: Clause 10.3.1
Clause 10.3.1 (TSE p.60 / EN p.57) gives two conditions and an order of preference:
- Pump sets shall be housed in a compartment having a fire resistance of no less than 60 min.
- That compartment shall be used for no other purpose than fire protection.
Order of preference (in the wording of the standard itself):
| Order | Location |
|---|---|
| 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 |
Clause 8.4 (TSE p.47 / EN p.44) completes this: water supply equipment such as pumps, pressure tanks and gravity tanks shall not be housed in buildings or sections of premises where hazardous processes or a risk of explosion exist. Water supplies, stop valves and control valve sets shall be installed so that they remain safely accessible even in the event of fire, secured against tampering and adequately protected against frost.
The pump room and its own sprinkler protection: Clause 10.3.2
Clause 10.3.2 (TSE p.61 / EN p.58) requires compartments for pump sets to be sprinkler protected and explains the practical solution where the pump compartment is separate: providing protection from the control valve sets in the premises might be impractical. In that case, protection might be provided from the nearest accessible point on the downstream side of the pump outlet non-return valve, via a subsidiary stop valve secured in the open position, together with a water flow detector in accordance with EN 12259-5 giving visible and audible indication that the sprinklers have operated.
The alarm equipment shall be installed either at the control valves or at a responsibly manned location such as a gatehouse (Annex I is referenced). The same clause also gives a dimension: a 15 mm nominal diameter drain and test valve shall be fitted downstream of the flow alarm so that the alarm system can be tested in practice.
Table I.1 (TSE p.158 / EN p.155) lists this signal in the row "water flow detector in the pump room, Clause 10.3.2, type A"; that is, at fire alarm level.
Temperature: Clause 10.3.3
Clause 10.3.3 (TSE p.61 / EN p.58) requires the pump set compartment to be maintained at or above the following temperature:
| Drive type | Minimum compartment temperature |
|---|---|
| Electric driven pump sets | 4 °C |
| Diesel driven pump sets | 10 °C |
These two values should not be confused with the general frost protection that also applies to the sprinkler valve room: Clause 8.1.3 (TSE p.45 / EN p.42) requires the supply pipe and the control valve set to be kept at at least 4 °C.
Temperature is also a monitored quantity. Clause H.2.7 (TSE p.157 / EN p.154): the minimum temperature of the sprinkler valve room and the pump room shall be monitored and an indication given if the temperature falls below the required minimum level. Table I.1 lists this as "low temperature in the pump room, Annex H, type B".
Ventilation: the single sentence of the standard
Clause 10.3.4 (TSE p.61 / EN p.58), headed "Ventilation", is a single sentence: compartments for diesel pump sets shall be provided with adequate ventilation in accordance with the recommendations of the supplier.
That is all the standard says on this subject. EN 12845 contains no provision on ventilation flow rate, louvre free area, air change rate, exhaust pipe routing, exhaust insulation or exhaust gradient for the pump room. These values shall be taken from the documentation of the diesel engine manufacturer and from local legislation.
The only EN 12845 sentence that binds the quantity of ventilation is in Clause 10.9.1 (TSE p.68 / EN p.65): there shall be enough fresh air available in the pump room at all times to keep the diesel pump set running within the limits specified by the manufacturer and EN 17451. Again, this is a performance requirement, not a number.
Drainage and lighting: outside the scope of EN 12845
The text of TS EN 12845+A2:2026 contains no provision on cross-section, gradient or capacity for pump room drainage, no lux value or emergency lighting requirement for lighting, and no clearance dimension for servicing. The clause headed "Drainage" (17.1.8, TSE p.115 / EN p.112) concerns pipework drainage, not pump room floor drainage.
Field note: these headings shall be closed by the project specification, the engine manufacturer documentation and local legislation. Writing a value down as "required by EN 12845" creates a claim whose source cannot be shown at inspection.
The geometry inside the room: suction conditions
The provisions that actually determine the size of the pump room are in Clause 10.6.
Clause 10.6.1 (TSE p.62 / EN p.59) requires, wherever possible, horizontal centrifugal pump sets 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.
- The pump centre line shall be no more than 2 m above the low water level of the suction tank (level X in Clause 9.3.5).
If this is not feasible, the pump may be installed under suction lift conditions or vertical turbine pumps may be used; but the standard says suction lift and submersible arrangements should be avoided and used only where a positive suction head is not practicable.
Suction pipe diameter and velocity limits:
| Condition | Minimum suction pipe diameter | Maximum velocity (at maximum demand flow) | Clause |
|---|---|---|---|
| Positive head | 65 mm | 1.8 m/s | 10.6.2.2 (TSE p.62 / EN p.59) |
| Suction lift | 80 mm | 1.5 m/s | 10.6.2.3 (TSE p.63 / EN p.60) |
Under suction lift conditions the height from the low water level to the pump centre line shall not exceed 3.2 m (10.6.2.3). The suction pipe shall be laid either horizontally or with a continuous slight rise towards the pump in order to prevent air locks (10.6.2.1). The pump suction shall be connected to a straight or taper pipe at least two diameters long; the taper pipe shall have a horizontal top side and a maximum included angle not exceeding 20°.
The NPSH provision added by A2 (Clause 10.6.2.1, TSE p.62 / EN p.59): the suction piping, including all valves and fittings, shall be designed so that at the maximum pump set flow shown in Table 14 and in accordance with EN 17451, the NPSH available at the pump inlet exceeds the NPSH required by at least 1 m. The NPSH calculation shall be made at the maximum anticipated water temperature.
Priming device and tank size
Clause 10.6.2.4 (TSE p.63 / EN p.60): a separate automatic priming device shall be fitted to each pump set. The device consists of a tank at a level higher than the pump and a sloping pipe connection from the tank to the delivery side of the pump, with a non-return valve fitted in that connection. The tank, the pump and the suction pipework shall be kept permanently full of water, even if there is leakage from the foot valve. If the water level in the tank falls to 2/3 of the normal level, the pump shall operate; alternatively an alarm shall be sent to a permanently manned location.
Table 15 (within Clause 10.6.2.4, TSE p.65 / EN p.62) is the only table of figures for the priming tank and its pipe:
| Hazard class | Minimum tank capacity (litres) | Minimum priming pipe diameter (mm) |
|---|---|---|
| LH | 100 | 25 |
| OH, HHP and HHS | 500 | 50 |
Valves, accessories and continuous flow
Clause 10.5 (TSE p.61 / EN p.58) sets the pump room pipe diagram:
- Unless the maximum water level is lower than the pump, a stop valve shall be fitted in the pump suction pipe.
- A non-return valve and a stop valve shall be fitted in the delivery pipe of each pump.
- In the case of booster pumps, a by-pass shall be installed around the pumps with a non-return valve and two stop valves, all of the same diameter as the trunk main.
- Any taper pipe fitted to the pump outlet shall expand in the direction of flow at an angle not exceeding 20°; valves on the delivery side shall be fitted after the taper pipe.
- Means shall be provided for venting all cavities of the pump casing.
- A continuous flow of water sufficient to prevent overheating shall be ensured while the pump is operating against a closed valve. This flow shall be taken into account in the system hydraulic calculation and in the pump selection. The outlet shall be clearly visible; where there is more than one pump, the outlets shall be separate.
- Diesel engine cooling circuits usually use the same water; if additional water is used, it shall also be taken into account.
- Tappings on the pumps for inlet and outlet pressure gauges shall be easily accessible.
Water temperature and strainers
Clause 10.4 (TSE p.61 / EN p.58): the water supply temperature shall not exceed 40 °C. Where submersible pump sets are used, the water temperature shall not exceed 25 °C unless the suitability of the motor has been proven for temperatures up to 40 °C.
Clause 9.3.6 (TSE p.54 / EN p.51): on pump sets operating under suction lift, a strainer shall be fitted upstream of the foot valve and positioned so that it can be cleaned without emptying the tank. On pumps supplied from an open tank under positive head, the strainer shall be fitted in the suction pipe outside the tank and a stop valve shall be provided between the tank and the strainer. The cross-sectional area of the strainers shall be at least 1.5 times the nominal area of the pipe and they shall not allow the passage of objects larger than 5 mm. (For strainers on town main connections, Clause 9.2 gives a different value: 1.5 times the area and 6 mm.)
The only maintenance interval that concerns the pump room
Clause 20.3.4.5 (TSE p.125 / EN p.122), within the annual routine: pump set suction strainers, the sump and the screens shall be inspected at least once a year and cleaned where necessary.
Frequently Asked Questions
What fire resistance does EN 12845 require for the pump room?
Clause 10.3.1 (TSE p.60 / EN p.57): pump sets shall be housed in a compartment having a fire resistance of no less than 60 min and used for no other purpose than fire protection. The order of preference is a separate building, a building adjacent to a sprinkler protected building with direct access from outside, and a compartment within a sprinkler protected building with direct access from outside.
At what temperature shall the pump room be kept?
Clause 10.3.3 (TSE 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.
Does EN 12845 give an m3/h figure for pump room ventilation?
No. Clause 10.3.4 (TSE p.61 / EN p.58) is a single sentence: compartments for diesel pump sets shall be provided with adequate ventilation in accordance with the recommendations of the supplier. There is no provision on flow rate, free area, exhaust routing or insulation in EN 12845.
Does the pump room have to be sprinkler protected?
Yes. Clause 10.3.2 (TSE p.61 / EN p.58): compartments for pump sets shall be sprinkler protected. Protection might be provided from the nearest accessible point on the downstream side of the pump outlet non-return valve, via a subsidiary stop valve secured in the open position together with a water flow detector in accordance with EN 12259-5.
Is there a limit on the suction water temperature?
Clause 10.4 (TSE p.61 / EN p.58): the water supply temperature shall not exceed 40 C. Where submersible pump sets are used, the water temperature shall not exceed 25 C unless the suitability of the motor has been proven for temperatures up to 40 C.
References
- TS EN 12845+A2:2026 Clause 8.1.3 (TSE p.45 / EN p.42)
- TS EN 12845+A2:2026 Clause 8.4 (TSE p.47 / EN p.44)
- TS EN 12845+A2:2026 Clause 9.3.6 (TSE p.54 / EN p.51)
- TS EN 12845+A2:2026 Clause 9.2 (TSE p.49 / EN p.46)
- TS EN 12845+A2:2026 Clause 10.3.1 (TSE p.60 / EN p.57)
- TS EN 12845+A2:2026 Clauses 10.3.2, 10.3.3, 10.3.4, 10.4, 10.5 (TSE p.61 / EN p.58)
- TS EN 12845+A2:2026 Clauses 10.6.1, 10.6.2.1, 10.6.2.2, Table 14 (TSE p.62 / EN p.59)
- TS EN 12845+A2:2026 Clauses 10.6.2.3, 10.6.2.4 (TSE p.63 / EN p.60)
- TS EN 12845+A2:2026 Table 15 (TSE p.65 / EN p.62)
- TS EN 12845+A2:2026 Clause 10.9.1 (TSE p.68 / EN p.65)
- TS EN 12845+A2:2026 Clause 20.3.4.5 (TSE p.125 / EN p.122)
- TS EN 12845+A2:2026 Clause H.2.7 (TSE p.157 / EN p.154), Table I.1 (TSE p.158 / EN p.155)
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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.