Fire Pump and Water Tank Requirements Under the Turkish Regulation (BYKHY)

A building's fire suppression systems only work if they are fed with enough water at enough pressure. The Turkish Regulation on Fire Protection of Buildings (BYKHY) sets the requirements for the fire water tank, the fire pump station, hydrants and hose cabinets. Tank durations (Article 92) and pump performance requirements (Article 93) are written directly into the regulation, and sprinkler system design must be carried out to TS EN 12845 under Article 96(5). NFPA 20 and NFPA 13 can be used as an additional layer or a good-practice reference, on condition that the minimum requirements of the regulation are met. This article summarises the logic of tank sizing, the components of the pump station and the requirement for standby and diesel pumps.

The Basic Logic of Tank Sizing

The volume of a fire water tank reduces to one relationship:

Tank volume = required flow × required duration

The "required flow" is the total water demand of the systems expected to operate simultaneously in the worst-case fire scenario. The "duration" is the period over which the system must sustain that flow without interruption; under BYKHY it follows the building hazard classes of Article 19: 30 minutes for low hazard, 60 minutes for medium hazard and 90 minutes for high hazard (Article 92(3)). Both must be chosen correctly so the tank is neither undersized (inadequate protection) nor oversized (unnecessary cost).

Water Tank Provisions in BYKHY (Article 92)

Article 7(12) covers refineries, fossil-fuel power plants, energy generation plants with an installed capacity of 500 MW or more, and industrial facilities such as factories with a total enclosed floor area over 2,000 m², together with their storage facilities and yards, built within or adjacent to forest areas. For a hydrant-only building, 1,900 l/min × 90 min = 171 m³ is the general minimum; in Article 7(12) areas the external hydrant tank must cover 5,700 l/min × 60 min = 342 m³.

Which Systems Are Assumed to Operate Simultaneously?

The tank is sized for the worst case. BYKHY's preliminary method is explicit here: the sprinkler flow calculated per Annex 8/B is added to the hose cabinet flow in Annex 8/C and, where there is a hydrant system, the hydrant flow, and the total is multiplied by the duration in Article 92(3) (Article 92(5)). Where a hydraulic calculation is made, the volume it gives governs (Article 92(4)). In the detailed hydraulic calculation, which systems are counted together depends on TS EN 12845 and the risk class:

Among international standards, some assume sprinkler and hydrant simultaneity and others take the "largest single system" approach; the BYKHY preliminary calculation uses the summation in Article 92(5). Choosing the correct simultaneity scenario is critical to arriving at a realistic tank volume.

Pump Performance Requirements (Article 93(1))

Fire pumps are defined by their rated flow and rated pressure. BYKHY limits the shape of the pump curve directly:

• The closed-valve (zero-flow) head may be at most 140% of the rated head.
• The head at 150% flow may not be less than 65% of the rated head.
• Provided the required pressure is met, the pump may be used for system demands up to 130% of its rated flow.

Pump control is pressure-actuated and may be fully or semi-automatic (Article 93(8)). Pumps may be driven by electric motors as well as by internal combustion engines or turbines (Article 93(3)).

Components of the Fire Pump Station

A tank alone is not enough; a pump station is required to deliver the necessary flow and pressure. A typical station comprises:

• Main fire pump: delivers the required system flow at the design pressure.
• Standby pump: of the same capacity as the main pump, usually diesel driven.
• Jockey (pressure maintenance) pump: makes up small leaks and holds system pressure, preventing unnecessary starting of the main pump.
• Controllers: each pump has its own controller, which must be locked; it is fitted with indicator lights for phase failure, phase sequence failure and control phase failure, and the main incoming circuit breaker cannot be reached without unlocking the panel (Article 93(6)).
• Auxiliary valves: auxiliary components such as an automatic air release valve and a circulation relief valve are required (Article 93(5)).
• Suction and discharge headers, test line and flow meter: for commissioning and periodic testing.
• Pressure switches and gauges: each pump has its own control pressure switch, located inside the controller, sensing water pressure through a pipe connection, protected against water hammer, with lower and upper settings adjustable separately and independently and lockable once set (Article 93(7)).

The suction conditions of the pump room (positive suction is preferred), ventilation, and the fuel tank and exhaust arrangements for the diesel pump are integral parts of the design. BYKHY also requires the pump room or station to be kept continuously above +4 °C for electric motor driven pumps and above +10 °C for diesel engine driven pumps (Article 93(9)); emergency lighting around the working area of devices needing service, inspection and adjustment (Article 93(10)); and a floor sloped for adequate drainage so that water is kept away from the pump, the driver and critical devices such as the controller (Article 93(11)).

Redundancy and the Diesel Pump

A pump failing during a fire is not acceptable, so BYKHY makes redundancy a direct requirement (Article 93(2)). The energy independence of the standby also matters: the system must operate during a power outage.

• Where the system uses one pump, a standby pump of the same capacity is required (Article 93(2)).
• Where there are several pumps, enough standby pumps are provided so that at least 50% of the total capacity is backed up (Article 93(2)).
• Where no diesel engine driven standby pump is used, the power supply to the fire pumps must come from a reliable source independent of the building's general electrical system (Article 93(4)). Where that cannot be achieved, a diesel standby pump is the practical solution.
• In critical buildings such as high-rise blocks, large warehouses and shopping centres, an electric main pump is generally supplemented by a diesel standby in practice; this is good practice rather than a separate written BYKHY requirement.
• The diesel pump fuel tank must have capacity for the run period required by the applicable standard.

Hose Cabinet and Hydrant Criteria

Fire hose cabinets are the first-aid firefighting hose systems inside the building. BYKHY gives the design values directly: for round semi-rigid hose cabinets without a fire service outlet, the design flow is 100 l/min and the design pressure 400 kPa, and pressure reducers are required where the pressure at the nozzle inlet exceeds 900 kPa (Article 94(1)(b)(5)). For lay-flat hose cabinets (TS EN 671-2), which may be used in buildings required to keep trained firefighting personnel, the design flow is 400 l/min and the design pressure at least 400 kPa (Article 94(1)(b)(6)). Design is based on achieving these values at the most remote or most critical cabinet, and the number of cabinets assumed to operate simultaneously feeds through into tank and pump capacity.

The hydrant system is installed for external fire service intervention. The design flow is at least 1,900 l/min, increased according to the building hazard class, with 700 kPa at the hydrant outlet (Article 95(2)). Hydrant spacing is 50 m in very high risk areas, 100 m in high risk areas, 125 m in medium risk areas and 150 m in low risk areas (Article 95(3)). An external hydrant system is mandatory in settlements planned separately from general settlement areas where the total footprint of the buildings exceeds 5,000 m², and is also installed in areas within the scope of Article 7(12) (Article 95(7)). As a site grows, hydrant numbers and total flow demand increase, which directly enlarges the tank and pump.

Tank Compartmentation and Continuity

BYKHY does not require the tank to be compartmented; it requires the portion reserved as fire reserve not to be used for any other purpose and to serve only the suppression systems (Article 92(2)). So that the system is never left without water during maintenance or a fault, the fire water tank should preferably be divided into at least two compartments. One compartment can then be cleaned while the other continues to feed the system. In addition:

• The tank should be fed from a clean water source with an automatic level make-up arrangement.
• Tank material should be corrosion resistant and stagnation of the water prevented.
• In critical facilities, continuity is assured by a compartmented tank rather than a single large one.

How BYKHY Relates to NFPA 20 and EN 12845

BYKHY does more than set a framework: the tank durations (Article 92) and the pump performance, redundancy and pump room requirements (Article 93) are written directly into the regulation. Sprinkler system design must be carried out to TS EN 12845 under Article 96(5); Article 96(1) lists water pumps among the components of the sprinkler system and requires components to comply with TS EN 12259.

• BYKHY Articles 92–93 — tank durations, minimum hydrant tank values, pump curve limits, standby pumps, power supply, controllers, pressure switches and pump room requirements.
• TS EN 12845 — sprinkler design, water supply flow and duration (mandatory under Article 96(5)).
• NFPA 20 / NFPA 13 — an additional layer or good-practice reference when an insurer, investor or international specification asks for it, on condition that the minimum requirements of the regulation are met.

Calculations must be consistent on a project. Mixed approaches — sizing sprinklers to EN 12845 and the pump to NFPA 20 — can create inconsistencies in water supply duration and flow definitions. Where an additional layer is required, a separate check is made against each standard and the more restrictive result governs; the regulatory requirements are met in every case.

Frequently Asked Questions

How does BYKHY determine fire water tank capacity?

The tank volume is the flow of the systems assumed to operate simultaneously multiplied by the duration. BYKHY gives the duration by building hazard class: 30 minutes for low hazard, 60 minutes for medium hazard and 90 minutes for high hazard (Article 92(3)). In the preliminary calculation the sprinkler flow per Annex 8/B is added to the hose cabinet flow per Annex 8/C and, where present, the hydrant flow (Article 92(5)); where a hydraulic calculation is made, its result governs (Article 92(4)). Where there is only a site hydrant system, at least 1,900 l/min for 90 minutes is required; in Article 7(12) areas the external hydrant system needs a tank for at least 5,700 l/min for 60 minutes (Article 92(7)).

Which systems are assumed to operate simultaneously in tank sizing?

In the BYKHY preliminary calculation the sprinkler flow (Annex 8/B), the hose cabinet flow (Annex 8/C) and, where there is a hydrant system, the hydrant flow are added together and multiplied by 30, 60 or 90 minutes according to the hazard class (Articles 92(3) and 92(5)). Where a hydraulic calculation is made, the volume it gives governs (Article 92(4)); in the detailed calculation the sprinkler side is designed to TS EN 12845 (Article 96(5)).

Is a standby fire pump mandatory under BYKHY?

Yes. Where the system uses one pump, a standby pump of the same capacity is required; where there are several pumps, enough standby pumps are provided so that at least 50% of the total capacity is backed up (Article 93(2)). A jockey (pressure maintenance) pump for making up small leaks is also common practice.

When is a diesel fire pump required?

BYKHY does not require a diesel pump as such, but it does require that, where no diesel engine driven standby pump is used, the power supply to the fire pumps comes from a reliable source independent of the building's general electrical system (Article 93(4)). Where that independent supply cannot be provided, a diesel standby pump is the practical solution. Where diesel engine driven pumps are installed, the pump room is kept continuously above +10 °C (Article 93(9)).

What flow and pressure are required at a fire hose cabinet?

For round semi-rigid hose cabinets without a fire service outlet, the design flow is 100 l/min and the design pressure 400 kPa; pressure reducers are required where the pressure at the nozzle inlet exceeds 900 kPa (Article 94(1)(b)(5)). For lay-flat hose cabinets (TS EN 671-2) the design flow is 400 l/min and the design pressure at least 400 kPa (Article 94(1)(b)(6)). Design is based on achieving these values at the most remote or critical cabinet.

When is a hydrant system mandatory?

An external hydrant system is mandatory in settlements that contain all types of uses and are planned separately from general settlement areas where the total footprint of the buildings exceeds 5,000 m²; it is also installed in areas within the scope of Article 7(12) (facilities such as refineries, fossil-fuel power plants, energy generation plants of 500 MW or more and factories with a total enclosed floor area over 2,000 m², built within or adjacent to forest areas) (Article 95(7)). The design flow is at least 1,900 l/min with 700 kPa at the hydrant outlet (Article 95(2)); hydrant spacing is 50, 100, 125 or 150 m depending on the risk level (Article 95(3)).

What equipment is in a fire pump station?

A typical station comprises the main fire pump, a standby pump, a jockey pump, a separate locked controller for each pump (Article 93(6)), a separate control pressure switch for each pump (Article 93(7)), automatic air release and circulation relief valves (Article 93(5)), suction and discharge headers, a test line with flow meter, and pressure gauges. Emergency lighting and drainage in the pump station are also required (Articles 93(10) and 93(11)). Pumps feeding the sprinkler system are components of that system (Article 96(1)) and are designed to TS EN 12845 (Article 96(5)); NFPA 20 may be requested as an additional layer.

How is the most critical scenario chosen for tank sizing?

The tank is sized on the scenario with the highest water demand among the facility's systems. In sprinkler design the most disadvantaged hydraulic area is selected, its flow multiplied by the required duration, and any simultaneous hydrant or hose cabinet flow added. As the storage hazard class rises, both flow and duration increase. Choosing the critical scenario correctly is what keeps the tank from being either oversized or undersized.

Is a single tank sufficient, or is a divided tank required?

So the system is not left without water during maintenance or a fault, the fire water tank should preferably be divided into at least two compartments, allowing one to be cleaned while the other continues to feed the system. In critical facilities this is an important continuity requirement. Tank material, clean water supply and an automatic level make-up arrangement are also considered. Compartmentation is not a written BYKHY requirement; the regulation requires the fire reserve not to be used for any other purpose and to serve only the suppression systems (Article 92(2)). The need for compartmentation is assessed against facility criticality and the chosen standard.

How do BYKHY, NFPA 20 and EN 12845 relate?

BYKHY writes the tank durations (Article 92) and the pump performance, redundancy and pump room requirements (Article 93) directly, and requires sprinkler design to be carried out to TS EN 12845 (Article 96(5)). NFPA 20 and NFPA 13 are used as an additional layer or good-practice reference when an insurer, investor or international specification asks for them, on condition that the minimum requirements of the regulation are met. Calculations should be consistent; mixing EN sprinkler design with NFPA pump design creates inconsistency.

Are the values in this article legally binding?

No. This article explains the fire pump and water tank requirements under BYKHY in a practical framework; values given with an article number are taken from the current consolidated text of the regulation. What is binding is the current text of the Regulation on Fire Protection of Buildings in force, TS EN 12845 and the approval of the authority having jurisdiction. Always check the current official text and consult a fire safety specialist where necessary.

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