5
Pumper
Apparatus
Overview
5
Knowledge Objectives
(1 of 2)
• Explain the importance of understanding
the fire pump and its systems.
• Describe the exterior and interior features
of a pumper.
• Define the term pump.
• Explain the basic operations of positivedisplacement pumps and centrifugal
pumps.
5
Knowledge Objectives
(2 of 2)
• Explain the different types of positivedisplacement pumps.
• Explain the different types of centrifugal
pumps.
• Describe a single-stage pump and a twostage pump.
5
Introduction
• Without pumps, fire fighters cannot discharge
water under pressure to extinguish fire.
• The driver/operator of the pump apparatus
must understand how pumps operate to be
able to fix problems that may arise.
• Do not memorize a sequence of tasks; the
driver/operator should have a thorough
understanding of how the pump operates.
5
Exterior of the Pumper
(1 of 4)
• The pumper is a very basic fire apparatus.
– Large fire pump with hose and tools to
extinguish fires
– Most common fire apparatus
– Cab sits on a steel frame.
– Attached to the frame are storage
compartments and the fire pump.
– Ground ladders are mounted on the side or
stored inside the compartment at the rear.
5
Exterior of the Pumper
(2 of 4)
• Supply hose and attack lines are stored in
the hose bed.
– May be uncovered or covered with a tarp for
protection
– Most pumpers carry preconnected attack lines
for quick deployment.
5
Exterior of the Pumper
(3 of 4)
• The pump panel is the most notable
device on the apparatus.
– May seem confusing until the driver/operator
learns the basics of pump operations
– Covered in stainless steel and has multiple
levers and gauges
5
Exterior of the Pumper
Courtesy of Jim Hylton
Courtesy of Jim Hylton
(4 of 4)
5
Interior of the Pumper: The Cab
• Inside the cab are all the controls to
operate the apparatus.
– Interior controls on the engine apparatus are
very similar to those on other large vehicles
with few exceptions.
• Controls to engage the fire pump or to operate
emergency lights
– Fire apparatus is not like any other vehicle
and should not be operated like other vehicles
5
Pumps
(1 of 3)
• Fires are extinguished when the proper amount
of water (GPM rate) is applied.
– Water is directed through a nozzle at the required
pressure to give the water stream enough reach to
penetrate to the seat of the fire.
– Pump pressurizes the water used to attack a fire
– The fire pump is defined as a provider of liquid flow
and pressure dedicated to fire protection.
5
Pumps
(2 of 3)
• Pumps alone do not create pressure.
– Pumps displace fluid, which causes fluid to
move or flow.
– Resistance to flow creates pressure.
– Higher pressure means less volume or flow.
– Higher flow means less pressure.
– Pumps cannot provide a high pressure and a
high volume at the same time.
5
Pumps
(3 of 3)
• Two sides to all pumps
– Intake side is where the water enters the
pump.
• Referred to as the “supply side” since it is where
the water is supplied to the pump
– Discharge side is where the water exits the
pump.
5
Types of Fire Pumps
• Fire service uses two types of pumps:
positive-displacement pumps and
centrifugal pumps.
– Each relies on different operating principles.
– Each offers different features.
5
Positive-Displacement Pumps
(1 of 9)
• NFPA 20: A positive-displacement pump
produces flow by capturing a specific
volume of fluid per pump revolution and
reducing the fluid void mechanically to
displace a pumping fluid.
• Positive-displacement pumps rely on
tightly fitting parts to function properly.
– Ideal for use as a priming pump for centrifugal
pumps
5
Positive-Displacement Pumps
(2 of 9)
• Can be used as high-pressure auxiliary
pumps or portable pumps
– Efficiency depends on the close-fitting moving
parts.
– Performance will deteriorate with wear and
excessive use.
• Two classifications
– Rotary pumps exhibit a circular motion.
– Piston pump have an up-and-down motion.
5
Positive-Displacement Pumps
(3 of 9)
• Piston pumps
– Use a cylinder to contain the fluid
– Draws water from the intake side and pumps
it out the discharge side
– Three moving parts: piston, intake valve, and
discharge valve
• Two types of piston pumps: single-acting
and double-acting
5
Positive-Displacement Pumps
(4 of 9)
• Single-acting piston pump
– Operation is very simple.
– Similar to a squirt gun
• Every pump on the lever discharges fluid
from a single-acting piston pump.
– Water is discharged only on a downward
movement, creating a pulsating effect.
– Single-acting piston pumps are not suitable
for use on an attack line.
5
Positive-Displacement Pumps
Adapted from Hale Products, Inc.
(5 of 9)
5
Positive-Displacement Pumps
Adapted from Hale Products, Inc.
(6 of 9)
5
Positive-Displacement Pumps
(7 of 9)
• Double-acting piston pump
– Lets water flow more continuously using one
piston
– Still has periods of limited flow
– Both valves at each end
5
Positive-Displacement Pumps
(8 of 9)
• Rotary pumps are typically used as the
priming pump for a centrifugal pump.
– Discharge a constant flow of water with each
revolution
• Rotary gear pump is typically used as a
priming pump.
– Driven by a 12-volt electric motor
5
Positive-Displacement Pumps
(9 of 9)
• Rotary vane pump uses small moveable
vanes to freely move in and out of rotor
slots to maintain a tight seal against the
pump casing.
– Vanes automatically maneuver in and out to
compensate for changes in the pump casing.
– Centrifugal force keeps the vane tightly
pressed against the pump casing, ensuring a
tight seal.
5
Centrifugal Pump
(1 of 11)
• Most common fire pump used today
• Replaced positive-displacement pumps on
modern fire apparatus
• Water flow discharge is based on
pressures at the discharge side of the
pump.
– At higher flow rates, the pump flows less
volume but creates higher pressures.
5
Centrifugal Pump
Adapted from Hale Products, Inc.
(2 of 11)
5
Centrifugal Pump
(3 of 11)
• Driver/operator needs to understand how the
pump works to maximize its potential in
firefighting operations.
• Pump operates on a principle of centrifugal
force: the outward force from the center of
rotation
– The pump receives water into the center or eye of the
impeller mounted inside the pump casing.
– Impeller transfers energy from the vehicle’s motor to
discharge incoming water
5
Centrifugal Pump
(4 of 11)
• Centrifugal pump can pump only water or
other liquids.
– No valves from intake to discharge side
– Not self-priming
– Takes advantage of incoming pressure on the
intake side to increase the discharge pressure
• Single-stage (one impeller) or multistage
(two or more impellers within one pump
housing turning on the same shaft)
5
Centrifugal Pump
• A single-stage pump has
one impeller that takes in
and discharges water out
of the pump.
– A single impeller supplies
100 percent of the total
water.
– Simple to operate
(5 of 11)
5
Centrifugal Pump
Adapted from Hale Products, Inc.
(6 of 11)
5
Centrifugal Pump
(7 of 11)
• Two-stage pump is the most common
multistage pump
– Two impellers enclosed in the pump casings
– Each impeller is identical in size and capacity.
– Transfer valve determines whether the pump
will be operated in a series/pressure mode or
parallel/volume mode
5
Centrifugal Pump
(8 of 11)
• Parallel/volume mode:
– Water enters each impeller and
is discharged into a common
discharge header.
– Use when more than 50 percent
of pump’s rated capacity needed
Adapted from Hale Products, Inc.
• Series/pressure mode:
– Water travels through one
impeller in the series.
– Most common operating position
for two-stage pumps
Adapted from Hale Products, Inc.
5
Centrifugal Pump
(9 of 11)
• Fire pump is rated by and tested to UL specs
• Pump must produce:
– 100% of rated capability at 150 psi (1034 kPa) for 20
minutes
– 70% of rated capability at 200 psi (1400 kPa) for 10
minutes
– 50% of rated capability at 250 psi (1723 kPa) for 10
minutes
– No rating provided for pressures over 250 psi
5
Centrifugal Pump
• Control valve on the pump
panel of a multistage
pump indicates whether
impellers are operating in
a parallel/volume or
series/pressure mode
• Two-stage pump is similar
to working from a hydrant
water supply and pumper
(10 of 11)
5
Centrifugal Pump
(11 of 11)
• Special multistage pumps are built to
produce high pressures for special
pumping requirements.
• Pump capacity has increased significantly
with the development of larger pumps with
larger impellers.
– 1950s: pumps delivered flows of 500 or 700
GPM (1892 or 2839 L/min)
– Today: pumps can flow at 2000+ GPM
(7570+ L/min)
5
Power Supplies for Pumps
(1 of 5)
• Driver/operator must know how pumps receive
power.
– Study schematics and manuals.
• Simplest form of power supply is available with
the portable pump.
– The pump is carried by two or more fire fighters to the
water source.
• Some apparatus have a pump mounted on the
front bumper.
5
Power Supplies for Pumps
Courtesy of Har-Rob Fire Apparatus, Inc.
(2 of 5)
5
Power Supplies for Pumps
(3 of 5)
• Power take-off (PTO) units are used for small
pumps like on tankers or tenders.
– Provides a less-expensive method of developing
pump power
– Provide a pump-and-roll capability for certain
apparatus
• A transfer case is the most common power
system found in pumps.
– Gearbox is mounted between transmission and rear
axle
5
Power Supplies for Pumps
Adapted from Hale Products, Inc.
(4 of 5)
5
Power Supplies for Pumps
(5 of 5)
• Pump speed is directly related to
transmission speed
– Transmission in first gear propels the pump at
a slow pace.
– Transmission in fifth gear turns it much faster.
• Automatic transmissions are made for
pumping operations that will lock into the
intended gear once the apparatus is in
pumping mode.
5
Summary
(1 of 2)
• The stainless steel pump panel is the most
notable device on the apparatus.
• A driver/operator who understands the pump
and its functions can operate with confidence.
• A pump is a mechanical device to move
fluids; fire fighters want the pump to move
water from a source to the fire through attack
lines.
5
Summary
(2 of 2)
• Fire service uses two types of pumps:
positive-displacement pumps and
centrifugal pumps.
• At higher flow rates (rpm) the pump flows
less volume but creates higher pressures.