Transcript Fire Detection and Suppression

Fire Detection and
Suppression
Chapter 4
Fire Pumps
Fire Pump Functions
• The main function of a fire pump is to
increase the pressure of the water that flows
through it.
— Inadequate or nonexistent municipal water
supply system
— Sprinkler systems and standpipe systems
4-1
Fire Pumps
Common Fire Pump Types
• Split-case pumps (see Fig. 4.2 in manual)
— Horizontal: not self-priming
(Continued)
4-2
Fire Pumps
Common Fire Pump Types
— Horizontal: not self-priming
(Continued)
4-3
Fire Pumps
Common Fire Pump Types
— Single-stage and multiple-stage
— Maintenance
4-4
–
Packing gland
–
Wear rings
Fire Pumps
Common Fire Pump Types
• Split-case pumps (cont.)
— Vertically mounted
4-5
Fire Pumps
Common Fire Pump Types
• Vertical shaft turbine pumps
(Continued)
4-6
Fire Pumps
Common Fire Pump Types
— Pressurized water source
4-7
Fire Pumps
Pump Drivers
• Engines or motors used to turn the pump
• Power requirements
• Types
— Electric motors
–
Required power
(Continued)
4-8
Fire Pumps
Pump Drivers
–
Mounting
(Continued)
4-9
Fire Pumps
Pump Drivers
–
Mounting (cont.)
–
Maintenance
(Continued)
4-10
Fire Pumps
Pump Drivers
• Types (cont.)
— Diesel engine drivers
–
Engine power
– Gear drives
–
Engine requirements
–
Cooling system
–
Fuel storage
– Maintenance
(Continued)
4-11
Fire Pumps
Pump Drivers
• Types (cont.)
— Steam turbines
–
Horizontal and vertical shaft
– Limited feasibility
4-12
Fire Pumps
Pump Controllers
• Govern pump operation
• Controllers for electric
motor-driven pumps
— Switches
— Multiple pumps
connected in parallel
— Manual shutdown
(Continued)
4-13
Fire Pumps
Pump Controllers (cont.)
• Diesel engine controllers
— Main function is to close the circuit between the
storage batteries and the engine starter motor.
— Alarm and signal devices
(Continued)
4-14
Fire Pumps
Pump Controllers (cont.)
— Pressure recording device
— Manual shutdown
— Weekly startup
4-15
Fire Pumps
Pump Installation Components
and Accessories
• Pipe and fittings
— Materials
— Valves
— Standards
–
–
Suction piping: NFPA 24, Standard for the Installation
of Private Fire Service Mains and Their Appurtenances
Discharge piping: NFPA 24 and NFPA 13, Standard for
the Installation of Sprinkler Systems
— Sizing
(Continued)
4-16
Fire Pumps
Pump Installation Components
and Accessories (cont.)
• Relief valves
— Prevent pressures that are high enough to
damage system piping or fittings
— Required only if pressure at churn is high enough
to damage system components
— Sizing
(Continued)
4-17
Fire Pumps
Pump Installation Components
and Accessories (cont.)
• Circulation relief valve: provides enough
water flow into and out of the pump to
prevent the pump from overheating when
operating at churn against a closed system
• Test equipment
— Test manifold
— GPM metering device
(Continued)
4-18
Fire Pumps
Pump Installation Components
and Accessories (cont.)
• Pressure maintenance pumps
— Prevent false starts due to fluctuations in
pressure of water supply to pump
— Small-capacity, high-pressure pumps that
maintain constant pressure on system
(Continued)
4-19
Fire Pumps
Pump Installation Components
and Accessories (cont.)
• Gauges
— Horizontal split-case pumps and vertical shaft
pumps
– One gauge near discharge port
–
One gauge near intake
— Vertical turbine pump: single gauge on discharge
side
(Continued)
4-20
Fire Pumps
Pump Installation Components
and Accessories (cont.)
• Component arrangement
— Typical arrangement
(Continued)
4-21
Fire Pumps
Pump Installation Components
and Accessories (cont.)
— Additional bypass line
(Continued)
4-22
Fire Pumps
Pump Installation Components
and Accessories (cont.)
— Horizontal-shaft pump installation (See Fig. 4.23
in manual)
— Vertical-shaft pump installation (See Fig. 4.24 in
manual)
• Standard performance specifications: NFPA
20, Standard for the Installation of Centrifugal
Fire Pumps
4-23
Fire Pumps
Testing, Inspection,
and Maintenance
• Testing fire pumps
— Piping: hydrostatic testing
— Acceptance testing
– Certified shop test curves
– Standard performance points:
1. Maximum of 140 percent of rated pressure at 0 gpm.
2. Minimum of 100 percent of rated pressure at 100
percent of rated flow.
3. A minimum of 65 percent of rated pressure at 150
percent of rated flow.
(Continued)
4-24
Fire Pumps
Testing, Inspection,
and Maintenance
• Equipment needed for pump tests
— One section of 2 1/2-inch or larger hose for each
hose connection on the test header
— One Underwriters playpipe for each hoseline
— Method for safely securing playpipes
— Pitot tube and gauge
— Method of measuring pump speed
— Voltmeter and ammeter
(Continued)
4-25
Fire Pumps
Testing, Inspection,
and Maintenance
• Conversion of velocity pressure to gpm:
Q=(29.83)(Cd)(D2)(√P)
Where:
Q=Flow in gpm
Cd=Coefficient of discharge
D=Discharge orifice diameter
P=Nozzle pressure
(Continued)
4-26
Fire Pumps
Testing, Inspection,
and Maintenance (cont.)
• Acceptance test on an electric horizontal
split-case pump
Step 1: Calculate the expected pitot pressure for
100 percent and 150 percent of the rated
flow.
Step 2: Connect all the hoselines and nozzles.
Step 3: Close the indicating control valve that
separates the pump from the fire system.
(Continued)
4-27
Fire Pumps
Testing, Inspection,
and Maintenance
• Acceptance test on an electric horizontal
split-case pump (cont.):
Step 4: Connect the ammeter and voltmeter to the
test leads in the controller or at any other
appropriate location.
Step 5: If using a handheld revolution counter to
measure pump speed, remove end plate of
motor for access to shaft.
(Continued)
4-28
Fire Pumps
Testing, Inspection,
and Maintenance
• Acceptance test on an electric horizontal
split-case pump (cont.):
Step 6: If end of shaft is not accessible, use a
strobe-type tachometer.
Step 7: Start the pump.
Step 8: Open the control valve in the line leading to
the test header and open the hose valves
for the first gpm measurement.
(Continued)
4-29
Fire Pumps
Testing, Inspection,
and Maintenance
• Acceptance test on an electric horizontal
split-case pump (cont.):
Step 9: Open and adjust sufficient lines to exact
required pitot pressures for 100 percent of
rated flow.
Step 10: When all readings are complete and
recorded, open and adjust additional
hoselines to the exact required pitot
pressures for 150 percent of the rated flow.
(Continued)
4-30
Fire Pumps
Testing, Inspection,
and Maintenance
• Acceptance test on an electric horizontal
split-case pump (cont.):
— Repetitions
– Manually controlled
–
Automatically controlled
–
Electrically driven pump
(Continued)
4-31
Fire Pumps
Testing, Inspection,
and Maintenance
• Acceptance test on an electric horizontal
split-case pump (cont.):
— Evaluating data
–
–
–
Performance curves
Pump speed
Voltage and current for electrically driven pump
• Acceptance test on a vertical shaft electric
pump
• Acceptance test on a diesel driven pump
4-32
Fire Pumps