Component and equipment of Fire Pump
1- Gate valve
It’s Control Flow of Water. It’s help to On & Off the flow control.
2- check valve
It prevents back flow, and allows only flow in on direction, and is installed in pump discharge line directly to prevent pumps from starting at a load or at the system pressure.
3- Suction header It prevents vortex
4- Discharge header
5- Diesel pump
It’s a 100% stand-by pump, operates in case of power failure with the failure of pressure make up process by the electric pump,Or even with the present of power if failure of pressure make up process.
6. Jockey pump
It’s the first pump to start in case of fire, It operates as a pressure maintenance pump so in case of a leakage in the system pressure it will makes the system pressure as recommended, and A jockey pump should be sized to make up the allowable leakage rate within 10 minutes or 1GPM (3.8 L/min), whichever is larger, and is used for this job instead-off starting the electric pump to protect it from starting until a serious problem occurs.
7- Electric pumps
It’s the second pump to start in case of fire; it’s the 100% duty pump.
8- Pressure relief valve
A valve being set at a pressure higher than the system pressure or shut off pressure of the diesel pump to protect the system from the very high pressure generated by the diesel pump in case of sudden acceleration.
9- Alarm check valve
It’s consist of:
Pressure switch (electric part) which gives a signal to fire alarm system in case of flow in pipes.
Mechanical alarm which done automatically by water flow in pipes.
10- Water flow meter
11- Diesel pump electric control panel and pressure sensing line
12- Jockey pump electric control panel and pressure sensing line
13- Electric pump electric control panel and pressure sensing line
14- Vortex plate
It’s installed in the tank in suction lines to prevent vortex in the tank water.
15- Electric pump casing relief valve
It’s reliefs the pressure on the pump to protect it from damage in case of pump work and no exit for water in the system, and is being set at the shut of head or higher than system pressure.
16- Stainless steel flexible joints
17- Automatic air vent
18- Tamper switch
It gives a signal when a gate valve closed.
19- Flow switch
It gives signal when a flow happened in a pipe.
An arrangement for pump room:
Sequence of Fire Pump Operation
All pipes of the wet system are maintained at a pressure higher than system demand pressure.At first in case of fire a sprinkler open or a fire hose cabinet will be used This will makes the pressure of water to goes down, all pumps sensing
lines matched to pressure transducer in pump control panel, when the pressure reach 6 bar the pressure transducer in jockey pump controller gives signal to start the jockey, if the pressure maintained constant or goes high this means it just a leak, and if the pressure reached 5 bar the electric fire pump will start as same as jockey pump, and if the pressure
reached 4 bar in any case the diesel pump will start by the same way.(all numbers is for example)
The fire pump operation is as follows
(a) Motor-Driven Pump. To start a motor driven pump, the following steps should be taken in the order given below.
(1) See that pump is completely primed.
(2) Close isolating switch and then close circuit breaker.
(3) Automatic controller will start pump if system demand is not satisfied (e.g., pressure low, deluge tripped, etc.).
(4) For manual operation, activate switch or pushbutton, or manual start handle. Circuit breaker-tripping mechanism should be set so that it will not operate when current in circuit is excessively large.
(b) Steam-Driven Pump. A steam turbine driving a fire pump should always be kept warmed up to permit instant operation at full rated speed.The automatic starting of the turbine should not be dependent on any manual valve operation or period of low-speed operation. If the pop safety valve on the casing blows, steam should be shut off and the exhaust piping examined for a possible closed valve or an obstructed portion of piping. Steam turbines are provided with governors to maintain speed at a predetermined point, with some adjustment for higher or low-
er speeds. Desired speeds below this range can be obtained by throttling the main throttle valve.
(c) Diesel Engine-Driven Pump. To start a diesel engine-driven pump, the operator should be familiar beforehand with the operation of this type of equipment. The instruction books issued by the engine and control manufacturer should be studied to this end. The storage batteries should always be maintained in good order to ensure prompt satisfactory operation of this equipment (i.e., check electrolyte level and specific gravity, inspect cable conditions, corrosion, etc.).
(d) Fire Pump Settings. The fire pump system, when started by pressure drop, should be arranged as follows.
(1) The jockey pump stop point should equal the pump churn pressure plus the minimum static supply pressure.
(2) The jockey pump start point should be at least 10 psi (0.68-bar) less than the jockey pump stop point.
(3) The fire pump start point should be 5 psi (0.34 bar) less than the jockey pump start point. Use 10-psi (0.68-bar) increments for each additional pump.
(4) Where minimum run times are provided, the pump will continue to operate after attaining these pressures. The final pressures should not exceed the pressure rating of the system.
(5) Where the operating differential of pressure switches does not permit these settings, the settings should be as close as equipment will permit. The settings should be established by pressures observed on test gauges.
(6) Example:
Pump: 1000-gpm, 100-psi pump with churn pressure of 115 psi.
Suction Supply: 50 psi from city — minimum static. 60 psi from city —maximum static.
Jockey pump stop = 115 + 50 = 165 psi.
Jockey pump start = 165 – 10 = 155 psi.
Fire pump stop = 115 + 50 = 165 psi.
Fire pump start = 155 – 5 = 150 psi.
Fire pump maximum churn = 115 + 60 = 175 psi.
(For SI units, 1 psi = 0.0689 bar.)
(7) Where minimum run timers are provided, the pumps will continue to operate at churn pressure beyond the stop setting. The final pressures should not exceed the pressure rating of the system components.
(e) Automatic Recorder. The performance of all fire pumps should be automatically indicated on a pressure recorder to provide a record of pump operation and assistance in fire loss investigation.
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