EN 12845 Pump Room Requirements: Ventilation, Drainage, Lighting

A pump room is not just a pump and a motor; it is ventilation area, floor drainage, emergency lighting and the exhaust connection as a whole. Working out what the pump room clause means on site.

Visiting the diesel pump room on a logistics warehouse project, the situation told its own story: the room was 2.2 m high, ventilated by a single 60 × 60 louvre, the door opened inward, rainwater stood on the floor for days, and the exhaust ran not out through the roof but into the technical corridor next door. The battery set had failed three times and nobody had asked why. The pump room requirements fit into one clause of EN 12845, yet about 70 % of site errors fall outside it.

This article is not about suction lift or NPSH; it is about the physical infrastructure of the room — walls, doors, ventilation area, floor falls, lighting levels, exhaust termination and service clearances.

What the clause says

The standard defines the compartment housing the pump sets in four parts:

• General — fire resistance of at least 60 minutes, with no other use permitted.
• Sprinkler protection — the pump room must itself be sprinkler protected.
• Temperature — at least 4 °C for electric drives and 10 °C for diesel.
• Ventilation — adequate ventilation for diesel pumps, to the manufacturer's instructions.

The standard gives no numerical ventilation rate; the engine manufacturer does, and the room designer must implement it. The order of preference in the general clause matters and is frequently skipped:

1. A separate building (most preferred);
2. A building attached to the sprinklered building, with direct external access;
3. A compartment inside the sprinklered building, still with direct external access.

The key phrase is direct external access. When the fire service arrives, they should not have to cross a lobby, corridor and lift; and a technician carrying a heavy battery in an emergency must be able to open the door from outside.

Fire resistance and the door

In practice, an REI 60 wall means at least 15 cm of reinforced concrete, or a drywall of two layers of 12.5 mm fire board over mineral wool. The door is an EI 60 certified to EN 1634-1, opening outward and self-closing. An inward-opening door is a design error: in a panic, fire pressure holds it shut, and the technician opening it from outside meets flame drawn through by the channel effect.

There must be no fall at the door threshold letting rainwater or wash water into the room, and the door should carry a "Sprinkler Pump Room — No Unauthorised Entry" sign.

Ventilation: the lifeblood of a diesel

Ventilation in a diesel pump room does three jobs: it supplies combustion air, cools the engine, and holds room temperature below the threshold. All three requirements are calculated separately.

Air requirement	Typical magnitude	Route
Combustion air	about 2.5 m³/min per 100 kW	Through the engine intake filter
Radiator cooling air	about 150–300 m³/min per 100 kW	Front louvre in, rear discharge
Room ventilation (temperature)	4–6 air changes per hour	Cross ventilation

A practical rule of thumb: for a 50–100 kW diesel pump, total free area of at least 1.2 m². Because a louvre's net free area falls to 50–60 % of gross once mesh and blade losses are counted, designing 2.0–2.5 m² gross is safe. Air inlet low (fresh air is dense), discharge high (hot air is buoyant). Put the discharge on the radiator side and let the engine fan push it out, and the room will not exceed 10 °C above ambient.

Natural ventilation is often insufficient and a mechanical assist fan is needed — but it must not stop in a power cut, so it belongs on the battery or generator supply. Do not close the louvre completely in winter; use partial, thermostatically controlled blades.

Drainage: the room must stay dry

The standard gives no drain count, but because the room may not be used for anything else and is itself sprinkler protected, sprinkler operation, pump gland leakage, test line discharges and rainwater through the louvre all end up on the floor. To get it out:

• Floor fall of at least 1 % toward the gully;
• Gully at least DN100, of a non-blocking type;
• The discharge must not connect directly to the sewer, because of back-flow risk; an interceptor with an air break is needed;
• Pump plinth height at least 10 cm, so water never reaches beneath the motor;
• The battery set at plinth top level, out of any flood path.

In most pump rooms I see, the floor fall is zero; where a gully exists it is blocked or capped and unusable. A technician draining the test line into a bucket leaves 200–400 L on the floor after every test.

Lighting: the EN 1838 emergency circuit

EN 12845 gives no lighting level, but a pump room counts as a high-risk task area under EN 1838. The practical requirement:

• General lighting at working level of at least 200 lux, to read gauges and valve labels;
• Emergency lighting of at least 15 lux, coming on within 0.5 s of mains failure;
• Duration of at least 1 hour;
• Fittings to IP54, protected against sprinkler discharge.

Self-contained LED fittings with integral batteries are preferable to a central battery supply; lighting then stays on even if the control panel fails.

Dimensions and service clearances

The standard gives no minimum clearance around the pump. The field rules:

• At least 0.8 m of clear service space on three sides of the pump body;
• 1.0–1.2 m on the motor side, for coupling removal;
• At least 1.0 m from the top of the motor to the ceiling, for lifting access;
• The battery set in the same compartment but at least 0.6 m from the control panel;
• The diesel fuel tank outside the room, or in a separate REI 60 compartment; if stored inside, a drip tray is mandatory.

Pump room height should be at least 2.5 m, and not below 3.0 m for diesel sets with large radiators. Where valves, a deluge station or an air receiver are mounted below the ceiling, a clear 2.2 m working height must still be preserved.

The diesel exhaust termination

This heading alone justifies the article: discharging the exhaust into the pump room or an internal corridor. The standard prohibits combustion gases re-entering the room and requires insulation and fall.

• The exhaust pipe is double-walled and insulated, with an outer surface safe to touch;
• It terminates above the roof or on an external elevation, no closer than 3 m to any louvre or window;
• Fitted with a rain cap or a 90° elbow termination;
• A condensate drain tee at the lowest point, discharging to a container;
• A silencer approved by the engine manufacturer, keeping noise within an 80 dBA limit.

Where the exhaust is left discharging into a technical corridor or a closed lift shaft, CO reaches a lethal threshold within five to ten minutes and the room reaches 60–80 °C — which turns the 60 minute fire resistance requirement into an empty shell.

Cooling: radiator or heat exchanger

EN 12845 does not restrict the diesel cooling method; there are two options:

System	Advantage	Disadvantage
Radiator and fan	No system water required, closed circuit	Very high air volume, room temperature rises
Heat exchanger	Low air volume, compact	Requires continuous flow from the sprinkler main (about 0.5–2 L/s)

Where a heat exchanger is selected, the water drawn from the pump discharge becomes part of the hydraulic calculation. Add that flow as cooling water demand, or the pump will fall short at rated duty.

Common field errors

• Exhaust discharging indoors — the most lethal and most frequent error.
• A single louvre, closed in winter — radiator air does not circulate and the engine shuts down above 90 °C.
• An inward-opening, locked door — the fire service cannot get in.
• Zero floor fall and no gully — the pump plinth corrodes and water sits under the motor.
• No emergency lighting — night-time fault response becomes impossible.
• Batteries in the hot or cold air path — radiator discharge air over the batteries takes them to 60 °C and they fail within six months.
• An internal fuel tank with no drip tray — a leak spreads across the whole floor.

Comparison with NFPA

NFPA 20 is more numerical here: pump room temperature, ventilation rate derived from engine heat rejection, exhaust termination height (at least 0.9 m above the roof) and door fire resistance (typically two hours) are all stated explicitly. EN 12845 defers to the manufacturer's instructions, leaving responsibility with the designer and the pump supplier. In practice the NFPA 20 figures can be used as a safe upper bound on EN 12845 projects too.

Turkish context

BYKHY treats the pump room as part of the sprinklered building and requires 120 minutes of fire resistance — stricter than the 60 minutes of EN 12845. In practice, apply the 120 minutes and layer all the other EN 12845 requirements on top. CE-marked pump sets arrive with EN 12845 documentation and a manufacturer's installation manual; the room designer's job is to implement the ventilation area in that manual. In field practice, however, the manual often stays unopened in the file, and building inspection rarely checks room dimensions.

Frequently asked questions

How much ventilation does a diesel pump room need?

The standard gives no number, deferring to the engine manufacturer. In practice, a 50–100 kW diesel pump needs at least 1.2 m² of net free area, roughly 2.0–2.5 m² of gross louvre. Always check the manufacturer's table.

What temperature must the pump room hold?

At least 4 °C for electric drives and 10 °C for diesel. Ten degrees is also optimal for the battery set.

What fire resistance is required?

At least 60 minutes (REI 60) under EN 12845. BYKHY requires 120 minutes in Turkey, so in practice 120 minutes is provided along with all the other EN 12845 conditions.

Where must the diesel exhaust terminate?

Directly outside, insulated, above the roof or on an external wall at least 3 m from any louvre. Discharging into an internal space, lift shaft or technical corridor takes CO and temperature past their limits within minutes.

How much clear space is needed around the pump?

The standard gives none; field practice is 0.8 m on three sides of the pump body, 1.0–1.2 m on the coupling side, and 1.0 m above.

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