Fire Pumps and Equipments

Fire Pumps: These are pumps that provide pressurized water to water quenching systems and are expressed by nominal flow rate and rated pressure value. Pumps must not be less than 65% of the nominal discharge head and the closed head (zero flow) discharge head must be no more than 140% of the nominal head elevation value and 150% of the discharge head height. Such pumps can be used for system requirements at 130% of the nominal flow rate, provided that the required pressure value is met. If a pump is used in the system, it must be a spare pump in the same capacity. If there are more than one pump, enough spare pumps will be used provided that at least 50% of the total capacity is backed up.

Pump rotation can be by electric motor as well as by internal combustion engines or turbines. If a spare diesel pump is not used, the energy supply of the fire pumps will be supplied from a reliable source and will be fed independently of the construction’s general electrical system. There must be auxiliary elements such as fire pumps, automatic air release valve, circulation relief valve.Each pump must have a separate control panel. The panel must be locked. The electrical control panel must be equipped with phase lights, phase-sequence fault, control phase fault, information lights. The on / off switch must not be accessed before the panel lock is opened.

Each pump must have a separate pressure switch. The pressure switches are located inside the control panel, the water pressure is protected by the pipe connection, protected against water hammer, the lower and upper values ​​can be set individually and independently and locked after set. Pump control can be pressure controlled full (automatic start-stop) or semi-automatic (automatic start-stop manually). If the discharge pressure of the fire pumps is not in the sprinkler installation, it is calculated as the algebraic sum of the following.

– The pressure value (mSS) required at the top of the service zone or system,
– Height from the pump to the highest hose valve (m)
– Friction loss between the pump and the highest hose valve.

These heights are the sum of; the minimum pressure is subtracted from the suction pressure. If the sprinkler system is in operation, the sprinkler system has a pressure demand. By adding the pressure losses of the pump, the highest pressure value is taken as the discharge pressure of the pump. When the pressure loss is calculated in a single zone system, the connections in the building entrance and / or the fire main pipe; up to the top hose valve feeding the roof manifold; it must be assumed that the whole process has passed. In a multi-zone system, it is assumed that the following link is used to calculate the pressure loss at the junction, from the connection pipe at the top, to the top two columns and from the connecting pipe at the intermediate floor. In a two-zone system, the pressure loss in the upper zone is calculated as a single-zone system. For systems with more than one zone, the pressure loss in the upper zone is calculated as in the lower zone of the two zone systems, as in the case of single zone systems.

To adjust the safety valve and calculate the required pump body pressure, a possible suction pressure is added to the height of the pump while it is stationary (the height in the non-flow state, which is not the discharge pressure characterizing the pump). This gives the maximum discharge pressure of the pump (in non-flow conditions). The discharge pressure required for the leak removal pump is outside the small flow rates; it is calculated like the fire pump’s. It should not be lower than the minimum pressure required by the water fire extinguishing system. The leak removal pump must be at least 1 gpm in capacity or capable of bringing the pressure to the required level within a tolerable 10 minute response time. The fire pump suction and discharge line shutoff valves will be of the rising type and will be connected to the control units with valve monitoring switches if necessary. If the diameter of the suction pipe differs from the pump suction flange, eccentric reduction must be used. Concentric reduction should be used if the diameter of the discharge pipe differs from the pump discharge flange. In case of diesel pump backup, diesel engines should be designed for reliable, first class and fire extinguishing systems. It must be equipped with the necessary equipment so that it can be operated for at least 30 minutes a week.The engine power must have at least 10% more power than the required maximum shaft power.There must be an automatic gas mechanism that will keep the engine speed constant at 10% range even under closed pressures and maximum load conditions. There must be two battery groups, main and backup.

The diameter of the suction pipe must be reduced so that the maximum water velocity of 4.5 m / s is not exceeded. The discharge line must not exceed 3 m / s.

Pump peripheral elements table

* NFPA 20-1996 was prepared using Table 4 instead of 31/2 according to Table 2-20.
** Valid for 10 diameters before the suction.
*** Pump flanges can be different from pipe diameter.

Detachable fire pump connection equipment

Diesel Fuel Depot

Fire pump pressure sensing line

Fire pump body types

Pump connection diagram

Source: Fire Extinguishing Installation and Smoke Evacuation Projects Z. SABAHATTİN BOZBEY