Fire pumps in brief

Fire Pump

1. FIRE PUMPS

2. FIRE PUMPS
General
A centrifugal pump for fire protection shall be
selected to operate at less than or equal to 150% of
the rated capacity. The pump should be selected at
capacities between 90% to 140% of the rated
capacity( clause 5.8.1 ).
It is a poor design practice to overdesign the fire
pump and the driver and depend on the pressure
relief valve to open and relieve the excess pressure

3. Requirements of Pump room
Indoor fire pump units should be physically
separated or protected by fire rated construction.
For a fully sprinklered pump room one hour fire
rating is required.
Emergency lighting and ventilation are required in
pump room.
Drainage-Flow should be pitched to adequate
drainage of escaping water from pump and other
accessories.

4. Piping
Steel pipe should be used for above ground
applications. For underground applications
NFPA 24 should be followed.
Steel pipes should be joined by means of
threaded, flanged (flanges welded to pipes
are preferred), grooved joints.

7. Suction piping
The size of the suction pipe for a single pump or of
the suction header pipe for multiple pumps
( operating together) should be such that with all
pumps operating at 150% of the rated capacity, the
gauge pressure at the pump suction flanges should
be 0 bar or higher.
Where the supply is the suction tank with its base at
or above the same elevation as the pump gauge,
pressure at the pump suction flange shall be
permitted to drop to -0.2 bar.

8. Suction piping………cont’d
Suction pipe should be sized such that with the
pumps operating at 150% of the rated capacity, the
velocity in that portion of the suction pipe located
within 10 pipe diameters upstream of the suction
flange does not exceed 4.57m/s and the size should
not be less than that specified in section 5.25
A listed OS&Y gate valve should be installed in the
suction pipe.

10. Suction piping………cont’d
No valve other than a listed OS&Y valve should be
installed in the suction pipe within 15.3m.
Elbows and Tees with a centre line plane parallel to
HSC pump are not permitted within 10 times the
suction pipe diameter.
Elbows with centre line plane perpendicular to HSC
pump shaft is permitted.
Where the pump and water tank are on separate
foundations provision shall be made for strain relief.

12. Suction piping………cont’d
For pumps taking suction from a water tank a vortex
plate shall be provided at the entrance to the suction
pipe.

14. Discharge piping
The size of the pump discharge pipe should not be
less than that given in section 5.25
Flanges welded to pipes are preferred.
Butterfly valves are permitted.
No pressure regulating devices should be installed
in the discharge pipe except as permitted in NFPA
20.
Pressure relief valves are required for diesel engine
pumps only if the 121% of the shut off head + static
suction pressure exceeds the system components
rating.

16. Discharge piping………..cont’d
Size of the relief valve should be as per section 5.25
Relief valve should be located between check valve
and the pump.
Relief valve discharge piping returning water back to
the storage tank should be piped independently and
not be combined with the discharge from other relief
valves.
Flow meter-size of the test line and flow meter
should be as per section 5.25

19. Jockey pump
Flow rate of a jockey pump should not be less than
the normal leakage rate.
Jockey pump should be sized to make up the
allowable leakage rate within 10 minutes or 3.8
litres/min which ever is larger.
For sprinkler systems jockey pumps are generally
sized to flow an amount of water less than or equal
to that required by a single sprinkler.

20. Centrifugal Pumps
Centrifugal pumps shall not be used where a static
suction lift is required.
Fittings (accessories) to be provided by the
manufacturer or an authorised representative.
1.Automatic air release valve
2.Circulation relief valve
3.Pressure gauges
Strainer:-Pumps that require removal of the driver to
remove rocks or debris from the pump impeller
should have a pipe lined strainer installed in the
suction line a minimum of 10 pipe diameters from
the suction flange.

21. Centrifugal Pumps………
cont’d
Foundation:-The base plate of the pump should be
securely attached to the solid foundation.
The foundation should be sufficiently substantial to
form a permanent and rigid support for the base
plate.

26. Vertical shaft turbine pumps
Wet Pit Installation
The required submergence should be obtained from
the pump manufacturer.

29. Electric drive for pumps
For pumps driven by electric motors where a reliable
power cannot be obtained from reliable power
sources , one of the following arrangements should
be provided.
Combination of two or more power sources
One of the approved power sources and an onsite
standby generator.
An approved combination of feeders constituting two
or more power sources.

30. Electric drive for pumps…
cont’d
Combination of one or feeders in combination with
an onsite standby generator
One of the power source and a redundant fire pump
driven by diesel engine.
Transfer of power to the fire pump controller
between normal power supply and one alternate
power supply should take place within the pump
room.

31. Fire pump’s controller
(Electric)
Primary Design
System operation is Primary
Protection of connected motor is secondary

32. Fire pump’s controller
(Electric)………….cont’d
Controllers should be located as close as is
practical to the motors they control and
should be within the site of the motors.
Interfacing with fire alarm system.
Pump running
Loss of Phase
Phase reversal
Controller connected to alternate power
supply.

33. Emergency Starting Circuits
If the contactor coil does not function for any
reason an emergency mechanical means is
available for closing the contactor

34. Service Entrance Rating
Utility can DIRECTLY connect to controller
Equipped with grounding lug bonded to the
enclosure
For added safety controller equipped with
isolating switch interlocked with enclosure
door.

35. Motor Contactor
No control circuit fuse
No voltage, frequency or other sensor to
prevent operation of contactor
No thermal overload relay
Contactor coil at LINE voltage

36. Circuit Breaker
Maintains locked rotor current for:
8 Seconds Minimum
20 Seconds Maximum
LRC=600% of Motor FLA
Minimum setting is 300% of the motor’s full
load Amps for 30 minutes minimum

37. Circuit Breaker Type
Magnetic device only
No thermal elements are permitted
Instantaneous Reset

38. Circuit Breaker Basic Design
Set to allow operation, not to protect the
connected electric motor

39. All motors shall be specifically listed for fire
pump service
Horsepower and locked rotor current motor
designation shall be as per NEC & NFPA 70
National Electric Code
All motors shall comply with NEMA standard
MG-1 and be marked as complying with
NEMA Design B standards

40. All motors shall be rated for continuous duty
and shall be applied only at voltages of +10
percent of the motor nameplate voltage.
Electric-motor-induced transients shall be
coordinated with 7-4.3.3 to prevent nuisance
tripping of motor controller protective devices.

42. Diesel Engine
Fuel Supply and arrangement
Fuel tank should have a capacity at least 1 gal/hp,
plus 5% volume for expansion and 5% volume for
sump
For multiple diesel engine pumps, separate fuel line
and separate fuel tank are required.
Inlet to the fuel supply line should be located so that
its opening is no lower than the level of the engine
fuel pump.

44. Diesel Engine…..cont’d
The engine manufacturer’s fuel pump static head
pressure limit should not be exceeded.
Galvanised steel or copper should not be used for
fuel piping
No shutoff valve should be installed in the fuel return
line to the tank.
Air supply and discharge ventilators should be
provided.

45. Controller for Diesel Engine
System operation is primary
Protection of the connected engine is
secondary

46. Engine Protection Circuits
Allows engine to continue operation:
When a low oil pressure condition exists
When a high cooling water temperature
condition exists.