Fire Pump Theory

1
Fire Pump Theory

• Mississippi Fire Academy
• Certification Division

2
Objectives

• 3-2.1, 6-2.1
• Produce effective hand or master streams, given
  the sources specified in the following list, so
  that the pump is safely engages, all pressure
  control and vehicle safety devices are set, the
  rated flow of the nozzles is achieved, and
  maintained, and the apparatus is continuously for
  potential problems.
• Internal Tank
• Pressurized source
• Static source
• Transfer from internal tank to external source

3
Positive Displacement Pumps

• Hydraulic Law When pressure is applied to a
  confined liquid, the same pressure is equally
  transmitted within a liquid in all directions

4
2 Basic Types

• Pistons Rotary
• Pistons
• Pistons moves back forth in cylinder
• Rotary- 2 types
• Rotary gear
• Rotary vane

5
Centrifugal Pumps

• Depends on velocity of water produced by
  centrifugal force to provide necessary pump
  discharge pressure

6
Principle of Operation Construction

• Disk tends to throw water
• Velocity is created is converted into more
  pressure
• Volume is dependent

7
Terms to be familiar with

• Impeller- transmit energy to pressure
• Volute- water passes and pressure is increased

8
3 Factors That Influence Pressure

• Amount of Water
• Speed the impeller is turning
• Pressure the water enters

9
Single-Stage Centrifugal Pump

• Constructed of one impeller

10
Two-Stage Centrifugal Fire Pumps

• Two Impellers within a single housing
• Allow delivery in Volume(parallel) or Pressure
  (series)

11
Pump Wear Rings Packing

• Higher rpm, the more wear
• Indication of wear
• Increased rpm to pump capacity
• To restore capacity
• Replace wear rings
• Replace hub of impeller
• When discharges are shutoff, heat builds
• Always circulate water

12
Pump Mounting and Drive Arrangements

• Cost, appearance, space requirements, and ease of
  maintenance are considerations

13
Auxiliary Engine-Driven Pumps

• Independent engine fire pumps

14
Power Take-Off Drive

• Mostly used on wildland, and mobile water supply
  apparatus.

15
Front-Mounted Pumps

• More susceptible to freezing temperatures
• Vulnerable to collisions
• Pump control are in front of the vehicle

16
Midship Transfer Drive

• Located in the drive line between the
  transmission rear axle

17
Rear Mount Pumps

• More weight distribution
• Gives more compartment space
• Driver is exposed to oncoming traffic

18
Pump Piping and Valves

• Corrosion resistant, and made of cast iron,
  brass, stainless steel, or galvanized steel

19
Intake Piping

• Tank Water
• Most fires can be extinguished
• 500 gpm or less should flow 250 gpm
• Greater than 500 gpm, flow at least 500 gpm
• External Water
• Primary piping is large diameter
• Round near the intake

20
Discharge Piping

• 750 gpm or greater should be equipped with at
  least 2 2½ discharges
• Smaller outlets used for preconnects
• Tank fill lines should be provided

21
Valves

• Should permit flow with minimum friction loss

22
Pump Drains

• Relieves pressure
• Drain lines used to drain water during freezing

23
Automatic Pressure Control Devices

• NFPA requires devices to operate within 3-10
  seconds with no more than 30 psi rise

24
Relief Valves

• Discharge relief valves
• Spring controlled pilot valves
• Alternative relief valves
• Intake relief valves
• Factory supplied
• Add-on device

25
Pressure Governor

• Regulates by mechanical or electronic means

26
Priming Methods and Devices

• Success depends on ability to create a lower
  pressure

27
Positive Displacement Pumps

• High rpm required
• 1,000-1,200 rpm
• Most require oil
• Seals gaps
• Preserve and prevent corrosion

28
Exhaust Primers

• Uses venturi principle
• Requires maintenance due to carbon deposits

29
Vacuum Primers

• Simplest type
• Line connected from intake manifold to intake of
  fire pump
• 2 dangerous conditions
• Explosives gases
• Water drawn into manifold

30
Pump Panel Instrumentation
31
Master Intake and Discharge Gauges

• Master Intake Gauge
• Measures positive negative
• Calibrated 0-600 psi positive, 0-30 inches
  negative
• Provides information of water available vacuum
• Master Pump Discharge Gauge
• Registers pressure leaving the pump

32
Tachometer

• Records engine speed in revolutions per minute

33
Pump Engine Coolant Temperature Indicator

• Reflects temperature of engine coolant

34
Pump Engine Oil Pressure Indicator

• Shows adequacy oil pressure

35
Pump Overheat Indicator

• Visual or audible indicator

36
Voltmeter

• Indicates condition of battery and alternator
  output by measuring voltage.

37
Pump Pressure Indicators (Discharge Gauges)

• Connected to individual discharges

38
Pumping Engine Throttle

• Used to increase or decrease engine speed during
  pumping operations

39
Primer Control

• Controls priming device for drafting

40
Water Tank Level Indicator

• Indicate the amount of water level in tank

41
Auxiliary Cooling Devices

• 2 types of auxiliary coolers
• Marine
• Immersion