CVFD Training – Pump
Operations
SFFMA Training Objectives
24-01.01 – 24-01.02
NET ENGINE PRESSURE
• Net Pump Discharge Pressure (new term)
• Actual amount of pressure being produced by
the pump.
• When taking water from a hydrant, it is the
difference between the intake pressure and
the discharge pressure.
• When drafting it is the total of the intake
pressure and the discharge pressure.
NOZZLE REACTION
• Counterforce directed against a person
holding a nozzle or a device holding a nozzle
by the velocity of water being discharged.
• Measured in pounds
• Nozzle reaction formulas NR= 1.57·d²·NP and
NR= 0.0505·Q·NP
POUNDS PER SQUARE INCH
(PSI)
• U.S. unit for
measuring pressure.
• Reflected on the
discharge gauge
• Called Pump
Discharge Pressure or
Engine Pressure
PUMP DISCHARGE PRESSURE
• ENGINE PRESSURE
• Actual velocity pressure (measured in PSI) of
the water as it leaves the pump and enters the
hoseline.
VELOCITY
• Speed; the rate of motion in a given direction.
It is measured in feet per second for the fire
service.
Water Hammer
Water moving through a pipe or hose has
both weight and velocity. The weight of
water increases as the pipe or hose size
increases. Suddenly stopping water moving
through a hose or pipe results in an energy
surge being transmitted in the opposite
direction, often at many times the original
pressure.
This surge is called Water Hammer
WATER HAMMER
• Force created by the rapid acceleration or
deceleration of water. It generally results
from closing a valve or nozzle too quickly.
• Can be up to seven (7) times the original
pressure.
GAUGES
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Master Intake gauge (Compound)
Master Discharge gauge
Discharge gauge (individual gauges)
Oil Pressure
Voltmeter
Tachometer (engine RPM)
Pump overheat indicator
Engine coolant temperature gauge
Master Intake Gauge
• Measures positive or negative pressure
• Calibrated from 0 to 600 PSI (usually) for
positive and from 0 to 30 inches of vacuum for
negative pressure
• Provides indication of residual pressure from a
hydrant or relay operation
• Provides indication of maximum capacity of
pump when at draft
Master Discharge Gauge
• Measures positive pressure
• Calibrated from 0 to 600 PSI
– Up to 1000 PSI on special pumpers
• Measures pressure as it leaves the pump and
before it gets to the individual gauges
• Always reads the highest pressure the pump is
producing
Discharge Gauge
• Individual gauges
measure the
pressure for each
individual discharge.
• Use these gauges
not the master
discharge gauge
when flowing any
line.
Oil Pressure Gauge
• Measures oil pressure of
the motor.
• Normal operating
pressures vary with
different brands of
apparatus.
• Variations from normal
may indicate pending
problems.
Voltmeter
• Provides a relative indication of battery
condition and alternator output by measuring
the drop in voltage as some of the more
demanding electrical accessories are used.
• Indicates the top voltage available when the
battery is fully charged.
• Measures drop when electrical demand is
high.
Tachometer
• Records the engine speed in revolutions per
minute (rpm)
• It can give valuable information about the
condition of the pump.
• May refer to the acceptance test rating panel
to check on pump efficiency (identification
plate on the pump panel)
Pump Overheat Indicator
• Audible or visual indicator
• * Overheating occurs when the pump
impeller is spinning, for prolonged periods,
but no water is being discharged
Pump Overheat
• Best place to check for
overheat is right here
• Best way to never
overheat the pump is to
always be moving
water.
Engine Coolant
• Engine coolant temperature gauge
– Shows the temperature of the engine coolant the normal operating range of the Detroit Diesel
Series 60 Engine is between 192° - 205°
Fahrenheit
– Caution: An engine that operates too cool is not
efficient. An engine that has an operating
temperature that is too high may be damaged.
Pump Theory and
Pump Equipment
TYPES OF FIRE PUMPS
• Piston
– Single, Multiple
• Rotary
– Gear
• Centrifugal
– Single-stage, Two-stage, Multiple-stage
Pump Equipment
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Centrifugal Pump
Multi-stage Pumps
Cavitation
Pressure Relief Valves/Governors
Positive Displacement Primers
Manual Pump Shift
Gauges
Auxiliary Cooler
Valves
Centrifugal Pump
• Components
– Impeller
– Eye
– Hub
– Vanes
– Volute
– Shroud
– Casing
Pump Impeller
Vane
Impeller eye
Shroud
Shaft
opening
Centrifugal Pump
• Rated at draft
• Can double its’ capacity with adequate
positive pressure
• Non-positive displacement pump
• Not self priming
• Cavitation occurs when  RPM without
corresponding increase in pressure
Centrifugal Pump
• Three factors influence pump discharge
pressure (PDP):
– 1)
– 2)
– 3)
Incoming Pressure
Speed of the impeller
Amount of water being discharged
• Single or Multi-Stage
• Maximum Discharge Pressure @ 150 psi plus
static pressure on hydrant
Rated Capacity
• A pump is rated @ draft, the following show
the capacity @ different pressures:
– 100% @ 150 psi (net pump pressure)
– 70% @ 200 psi (net pump pressure)
– 50% @ 250 psi (net pump pressure)
Rated Capacity
• When connected to a positive pressure
source, the capacity of a pump can be
doubled (assuming that the source is of
adequate size and pressure).
• The capacity of a pump can also be increased
when using multiple intakes or increasing the
size of the supply line.
Two-Stage Centrifugal Pumps
• Single vs. Multi-Stage
– Pressure (series) vs. Volume (parallel)
– Most operations in pressure mode
– 50 % rule
– Change over @ 50 psi net pump pressure
– Transfer valve found on pump panel, usually with
indicator light
Two-Stage Centrifugal Pumps
• The two-stage pump has two impellers mounted
within a single housing.
• Generally, the two impellers are identical and have
the same capacity.
• What gives the two-stage pump its versatility and
efficiency is its capability of connecting these two
stages in series for maximum pressure or in parallel
for maximum volume by use of a transfer valve.
Two-stage Centrifugal pump
• Pumping in the Volume (Parallel) Position
– When the pump is in the volume position, each
of the impellers takes water from a source and
delivers it to the discharge.
• Pumping in the Pressure (Series) Position
– When the transfer valve is in the pressure
position, all the water from the intake manifold is
directed into the eye of the first impeller.
– The first stage increases the pressure and
discharges 50 to 70 percent of the volume
through the transfer valve and into the eye of the
second impeller.
– The second impeller increases the pressure and
delivers the water (at the higher pressure) into
the pump discharge port.
Two-Stage Centrifugal Pumps
• Each fire pump manufacturer has
recommendations for when the transfer valve
on their pump should be in the volume or
pressure position.
• The process of switching between pressure
and volume is sometimes referred to as
changeover.
Pump packing
• Number of drops from packing.
– Water should drip, not run from packing gland
• New “Ceramic” packing
– Must have temperature relief valve to protect
ceramic disk
Cavitation
What is Cavitation?
Cavitation
• Firefighters definition:
– Water is discharged from the pump faster than it
is coming in.
• Cavitation:
– A condition in which vacuum pockets form in the
pump and causes vibrations, loss of efficiency, and
possible damage.
Cavitation
• During Cavitation:
– The pressure at the eye of the impeller falls
below normal atmospheric pressure.
– The water boils faster at temperatures less
than normal atmospheric pressure.
– Steam and air bubbles are created.
– The air bubbles move outward in the impeller
and into the high-pressure zone.
– The air bubbles collapse, producing noise and
vibration.
Cavitation
• To Avoid Cavitation:
– Intake pressure from pressurized sources should
not drop below 20 psi.
– Cavitation can be recognized by the fact that
increasing the engine rpm does not result in an
increase in discharge pressure.
TRANSFER VALVE
• Only on Pressure/Volume Pumpers
• Switched by: Electric switch, Pneumatic shift,
Water-hydraulic, or Manual hand-wheel
• Changes pump from Pressure (Series) – to
Volume (Parallel)
• Switched when pumping greater than 50% of
the rated capacity of the pump
TRANSFER VALVE
• This is an electric
transfer switch
• Other switches can be:
– Pneumatic
– Hydraulic
– Manual
TRANSFER VALVE
• This is a manual backup to the transfer
switch
POWER TRANSFER
POWER TRANSFER
• Engine to wheels
• Engine to fire pump
Pump drives
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Mid-ship mount
Front mount
PTO
Rear mount
flywheel
Mid-Ship Mount
• Mid-Ship mount: a split-shaft gear case
located in the drive line between the
transmission and the rear axle.
• Unit will pump or drive, not both.
Power Take-Off
• Power is taken off the transmission before it gets to
the back wheels for “pump and roll” operation.
• The PTO unit is powered by an idler gear in the truck
transmission.
Front mount pump
• Power to drive comes off of the front of the
crankshaft.
• Pump sizes are limited to 1250 GPM max.
Electric Pump Shift
Electrical switch
transfers power from
road (driving) to pump
(firefighting)
Electric switch operates a
hydraulic or pneumatic shift
mechanism in the transfer
case
Pneumatic
Pump
Shift
TYPES OF PRIMER PUMPS
• ROTARY GEAR
• ROTARY VANE
• VACUUM
• EXHAUST
Positive Displacement Primers
• Types
– Rotary
• Rotary Gear
• Rotary Vane
– Piston
– Exhaust
• Most Common - Rotary Vane
• Required for Drafting
Positive Displacement Primers
• Rotary Gear
– Commonly used in hydraulic systems
– The pump imparts pressure on the hydraulic fluid
by having two intermeshing rotary gears that force
the supply of hydraulic oil into the pump casing
chamber.
Positive Displacement Primers
• Rotary Vane
– A rotor with attached vanes is mounted off-center inside
the pump housing.
– Pressure is imparted on the water as the space between
the rotor and the pump housing wall decreases.
• Piston
– Pump using one or more reciprocating piston to force
water from the pump chamber.
Vacuum Primer
• Used only on gasoline engine driven fire
apparatus.
Positive Displacement Primers
• Exhaust Primers
– Exhaust primes are still found on some older
pieces of apparatus.
– Exhaust gases from the vehicle’s engine are
prevented from escaping to the atmosphere by
the exhaust deflector.
– The gases are diverted to a chamber where the
velocity of the gases passing through a venturi
creates a vacuum.
Venturi Primer
Venturi Primer
Positive Displacement Primers
• “Older” priming pumps require an oil reservoir.
• “New” priming pumps are environmentally safe
requiring no priming oil.
• Both make a distinctive
sound when operating
Positive Displacement Primers
• Most are electrically
driven
• For pumps larger than
1250 GPM capacity,
operate no more than
45 seconds.
• May overheat if used for
greater period of time
PRESSURE RELIEF SYSTEMS
Intake Pressure Relief Valves
Pressure Relief Valves
Pressure Governors
Intake Pressure Relief Valves
• Piston intake relief valves decrease the
potential for a water hammer.
• Two types of pressure relief devices:
– Piston intake relief valve
– Dump valve (on pump)
– Should be preset @ 100 PSI
– Can be set from 50 to 175 PSI
Intake relief valves-dump valves
• Relieves pressure from incoming supply lines,
before it goes into the pump.
Pressure Relief Valves
Waterous PRV
Hale PRV
Pressure Relief Valves
• Pressure relief valves must be set while
pumping the desired pressure with water
flowing.
• Must be set at highest pressure
necessary (gate back other lines).
• Pressure relief valves do not provide
cavitation protection.
Pressure Relief Valves
• They prevent an excessive amount of
pressure being transferred to another line.
• Engine rpm will not fluctuate as lines are
opened or closed.
• Pressure Relief Valves divert water
internally.
Relief Valve Operation
Manual Throttle
• Operated via a cable to
the fuel system.
• CCW to increase and
CW to decrease speed.
• Red button in center is
the Emergency ShutDown.
Pressure Governors
• Pressure governors regulate engine pressure
by adjusting engine rpm to compensate for
attack lines being opened or shut.
• This prevents an excessive amount of pressure
being transferred to another line.
• Engine rpm will fluctuate as lines are opened
or closed.
Pressure Governors
• Pressure governors must be set while
pumping the desired pressure.
• Must be set at highest pressure
necessary (gate back other lines)
• Pressure governors provide cavitation
protection.
– If the pressure governor senses an increase
in rpm without a corresponding increase in
pressure, the engine will return to idle after
3-5 seconds.
Electronic Pressure Governor
• Seagraves version
Electronic Pressure Governor
• Quality version
Electronic Pressure Governor
• Detroit Diesel Fire
commander
• On all E-One Fire
Apparatus
Movie Time
“Pressure Governor Video”
Manual
Pump
Shift
Manual Pump Shift
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Provides back-up
Usually located on pump panel
Often require two people to operate
Back-up throttle may have to be used
Exercise manual shift often (weekly)
Auxiliary Coolers
Auxiliary Coolers
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Allows water from pump to cool engine
Use when temperature exceeds normal level
Close when temperature returns to normal
Keep in closed position
Auxiliary Cooling Systems
• Two basic types
– Immersion
– Marine
• System uses water from the pump which is
circulated through a closed system to
decrease the temperature of the coolant
found in the radiator
Auxiliary Cooling Systems
• Auxiliary cooling devices should be used when
the temperature of the engine is greater than
the manufacturer recommends.
• When opened, the auxiliary cooler will
temporarily decrease the engine temperature,
allowing time to remove attack crews and move
another apparatus into place to resume
operations.
Auxiliary Cooling Systems
• Some manufacturers supply a radiator fill
valve that can be used to fill the radiator if the
coolant level drops too low for effective
cooling.
• If used, the cooling system must be serviced system flushed and refilled with the correct
amount of antifreeze.
Valves
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Main intake valve (suction), keystone, piston, MIV*
Auxiliary intake valve (2½)*
Tank-to-pump valve
Tank fill valve
Discharge valve
Pump drain valve
Discharge drain valve
Intake drain valve
Large Intake Valves
Small Intake Valve
• 2 ½” intake valve connects directly into the large
intake piping
• 2 ½” female swivel
• Intake flow capacity 1000+ GPM
Water Supply
Water Supply
• Booster tanks
• Positive pressure sources
– Hydrants and other pumps
• Drafting
Booster Tank
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Sizes
Tank-to-pump valve
Use only one handline
Obtaining positive water source
Refill as soon as possible
Tank-to-Pump Flow Test
• This test must be conducted on all apparatus
that are equipped with a water tank.
• NFPA 1901 states that piping should be sized
so that pumps with a capacity of 500 gpm or
less should be capable of flowing 250 gpm
from their booster tanks.
Tank-to-Pump Flow Test
• Pumps with capacities greater than 500 gpm
should be able to flow at least 500 gpm from
their booster tanks.
Hydrant Operations
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Two types of hydrants
Steamer should face street
Blue reflectors assist in locating
Should be color coded to main size or GPM
flow
• MUD Districts may not color code
• Private hydrants-Apartments, Businesses may
or may not be maintained
Hydrant Operations
• When opening a dry barrel hydrant, be certain to
open it all the way.
• If it is not opened fully, the drain valve at the base
of the hydrant may be open at the same time
water is coming in from the main.
• This flow of water washes away the gravel that is
supporting the body of the hydrant.
Hose and Nozzles
• Limitations
– The limitations with fire hose deal
specifically with GPM and friction loss, as
well as pressure limits.
– The limitations of nozzles deal specifically
with capacity and function.
Pump Discharge Pressure
• Pump Discharge Pressure = Nozzle Pressure
+
Friction Loss + Appliance Loss + Pressure Due To
Elevation Changes
PDP = NP + TPL
PDP = Pump discharge pressure
NP = Nozzle pressure in psi
TPL = Total pressure loss in psi (appliance,
friction and elevation losses)
Pump Discharge Pressure
Fire Service Hydraulics
• Calculating Additional Water Available
When a pumper is connected to a hydrant and
is not discharging water, the pressure shown
on the intake gauge is the static pressure.
When the pumper is discharging water, the
pressure shown on the intake gauge is the
residual pressure.
Fire Service Hydraulics
• Calculating water (cont..)
The difference between the two pressures is
used to determine how much water is
available, and consequently the number of
additional lines available.
Percent Drop = (Static - Residual)(100)
Static
Fire Service Hydraulics
• Example: A pumper is supplying one line with 250
gpm flowing. The static pressure was 70 psi and the
residual pressure is 63 psi. How many lines can be
added?
• Percent drop = (70 - 63)(100)
70
(7)(100) =
700 = 10 psi drop
70
70
Fire Service Hydraulics
Water Available Table
Percent Decrease
Water Available
0 - 10%
3 x Amount
11 - 15%
2 x Amount
16 - 25%
Same Amount
Over 25% Less than is being delivered
Elevation Pressure
• Water exerts a pressure of 0.434 psi per foot of
elevation.
• When a nozzle is operating at an elevation higher
than the apparatus, this pressure is exerted back
against the pump.
• To compensate for this pressure “loss,” elevation
pressure must be added to friction loss.
*Elevation Pressure*
• Formula for multi-story buildings:
– (EP)=5psi x (number of stories -1)
• Formula for elevation pressure
– (EP)=0.5H
Elevation Pressure
•
EP=0.5H
– EP = Elevation pressure in psi
– 0.5 = A constant
– H = Height in feet
Pumping Operations
PRESSURIZED OPERATIONS
• HYDRANT-MOST COMMON
• RELAY OPERATIONS
• BOOSTER TANK
Standpipes and Sprinklers
• Pumpers will generally position as close as
possible to the sprinkler or standpipe FDC.
• This location should be established during preincident planning activities.
• There are situations when pumpers supporting
sprinklers or standpipes must give priority to
other fire apparatus (aerial apparatus).
Standpipes and Sprinklers
• Fire Department Connection (FDC) usually
have a 2 ½” swivel connection.
• Hook up a minimum of two 2½ hoselines or
one 3” hoseline. (textbook)
• LDH hose should be used with adapter (real
life)
• Reverse lay to nearest hydrant
Standpipes and Sprinklers
• It is a general rule of thumb that one 1000
gpm rated pump should supply the FDC for
every 50 sprinklers that are estimated to be
flowing.
PRV Systems
• Pump the designed pressure, if known.
• If the designed system pressure is unknown:
– 100 psi + 6 psi per floor to the top floor of the
zone
• When pumping into a PRV system, the
standpipe outlet pressure cannot be raised
above its designed pressure.
Non-PRV Systems
• Standpipe:
– Fog Nozzle: 150 psi + 5 psi per floor
– Solid Stream 65 psi + 5 psi per floor
• Sprinkler:
– 150 psi + 5 psi per floor
• Elevation loss is calculated to the fire floor
• Mixed systems PRV & Non-PRV should be
treated as a Non-PRV
FDC Impairments
• Frozen swivel
• use a double male with a double female
• Unusable due to vandalism
• connect hose at the first-floor level riser
• PRV’’s limit pressure and volume going
out or in!
DRAFTING
•Primary water source
for rural fire
protection
•Portable water
supplies
•Static water supplies
Drafting
• 3 primary considerations for selecting a site;
1) Amount of water available
2) Type of water available
3) Location accessibility
• Source should have 24 inches of water above
and below the strainer
Drafting
• All fire pumps meeting NFPA and Underwriter’s
Laboratories requirements are rates to pump
their capacity at 10 feet of lift.
• If the lift is less, the capacity is higher.
• If the lift is greater, the capacity decreases.
Drafting
• Theoretical Lift
– In the U.S. system of measurement, at sea level a
pump could theoretically lift water 33.8 feet.
• Maximum Lift
– The maximum lift is no more than 25 feet.
• Dependable Lift
– The height a column of water may be lifted in
sufficient quantity to provide a reliable fire flow.
Drafting
• The maximum lift considered reasonable for
most fire department pumpers is about 20
feet.
• At 20 feet of lift, the amount of water that can
be supplied is only about 60% of the rated
capacity of the pump.
Drafting
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•
•
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Use side intakes
Close pump to tank valve
Remove keystone or piston intake
Connect hard suction
Can prime either in or out of pump gear
When in pump gear, increase rpm’s to 1000 to 1200
and pull primer for not more than 45 seconds.
Drafting
• Priming typically requires 10 to 15 seconds.
• If priming is not obtained in 30 seconds, stop and
check for problems.
• Most common problem is air leak.
• After pump has been primed, increase pump
pressure to 50-100 psi prior to opening any
discharge.
• Open discharge valve SLOWLY.
• If pressure drops, momentarily engage primer.
Pump & Dump
Multiple Draft Tanks
Relay Operations
Relay Pumping
• Necessary when the required GPM flow of the attack
pumper cannot be met because of friction loss in the
supply line
• Pump pressure is based on GPM needed and
distance between pumpers.
• 20-50 psi residual in addition to friction loss
• Relay initiated by pumper at water source.
Relay Pumping
• Intermediate pumpers - close pump to tank valve,
open 2½” discharge until water discharges, close
discharge, place in pump gear and open supply to
next pumper
• Discharge pressures should not exceed 200 psi. If
pressure required to supply water is greater than 200
psi, another pumper or additional lines are needed.
Relay Pumping
• Relay is designed to deliver volume, not
pressure
• Relay is terminated by attack pumper, by
decreasing pressure, followed by next pumper
in relay, etc..
DUAL PUMPING OPERATION
Dual Pumping
• One strong hydrant may be used to supply
two pumpers.
• One pumper is connected to the hydrant to
inside of the intake.
• The second pumper is connected to its intake
side for the first pumper.
• The pumpers are connected intake to intake.
DUAL PUMPING SET-UP
(HIGH-VOLUME SET-UP)
E 45
E7
TANDEM PUMP OPERATION
Tandem Pumping
• Is a short relay for high rise buildings (This will
be a high pressure operation).
• Becomes necessary after 40 stories (roughly
300 psi).
• High pressure engines reverse lay from the
FDC to a safe area (falling glass).
• Supply engine will reverse lay to the hydrant.
TANDEM PUMPING SET-UP
(HIGH-PRESSURE RELAY)
E/O
E/O
E7
E 45
60 STORY
BLDG.
Supplemental Pumping
L93
E61
E70
E52
Supplemental Pumping
E70
L 93
E61
E52
Questions
Basic Principles of Hydraulics
• Excessive Pressure- causes may include
incorrect calculation of total engine pressure,
shutting down of additional lines or opening
of intake without the use of pressure governor
• Water Hammer- force created by the rapid
deceleration of water. It generally results
closing a valve or nozzle too quickly!
from
Basic Principles of Hydraulics
• Static Pressure - stored potential energy
available to force water through
pipes, fittings, fire hose and
adapters.
• Residual Pressure - that part of the total
available pressure not used to
overcome friction loss or gravity
while forcing water through pipes,
fittings, fire hose and adapters.
Basic Principles of Hydraulics
• Normal Operating Pressure pressure found in a water
distribution system during normal
consumption demands.
• Flow Pressure - forward velocity
pressure at a discharge opening
while water is flowing.
Basic Principles of Hydraulics
• Negative Pressure - an area with a
pressure less than that of the
atmosphere; when calculating
engine pressure and pumping to an
lower than the pump, a
“negative” pressure will have to be
added to the equation in order to
correctly figure the engine pressure.
area
Basic Principles of Hydraulics
• Cavitation - a condition in which vacuum
pockets form in the pump and cause
vibrations, loss of efficiency, and possible
damage
• Displacement - volume or weight of a fluid
displaced by a floating body of equal weight;
amount of water forced into the pump, thus
displacing air
Basic Principles of Hydraulics
• Elevation Pressure - the gain or loss of
pressure in a hoseline due to change in
elevation
• Flow Pressure - pressure created by the rate
of flow or velocity of water
coming
from a discharge opening
Basic Principles of Hydraulics
• Friction loss - loss of pressure created
by the turbulence of water moving
against the interior walls of the hose or
pipe
• Gallons per minute - unit of volume
measurement used in the U.S. fire
service for water movement
Basic Principles of Hydraulics
• Hydrant pressure - amount of pressure
being supplied by a hydrant without
assistance
• Head pressure - water pressure due to
elevation; for every one-foot
increase in elevation, 0.434 psi is
gained
Basic Principles of Hydraulics
• Net pump discharge pressure - actual amount of
pressure being produced by the pump. When
taking water from a hydrant, it is
the
difference between the intake
pressure and the discharge pressure.
• Nozzle pressure - the amount of pressure
required at the nozzle to produce an
effective fire stream.
Basic Principles of Hydraulics
• Nozzle reaction - counterforce directed
against a person holding a nozzle or a
device holding a nozzle by the
velocity
of water being discharged
• Pounds per square inch - U.S. unit for
measuring pressure
• Pressure - force per unit area measured in
pounds per square inch
Basic Principles of Hydraulics
• Pump discharge pressure - actual
velocity pressure (measured in
pounds per square inch) of the
water as it leaves the pump and
enters the hoseline.
• Velocity - speed; the rate of motion in a
given direction.
Principles of Pressure
1. Fluid pressure is perpendicular to any
surface on which it acts.
2. Fluid pressure at a point in a fluid at
rest is of the same intensity in all
directions.
3. Pressure applied to a confined fluid
from without is transmitted equally
all directions. (fire pump)
in
Principles of Pressure
4. The pressure of a liquid in an open
vessel is proportional to its depth.
5. The pressure of a liquid in an open
vessel is proportional to the density of
the liquid.
6. The pressure of a liquid on the bottom of a
vessel is independent of the
shape of
the vessel.
Fire Service Hydraulics
Friction Loss the part of the total pressure lost while forcing
water through pipe, hose, fittings, adapters,
and appliances. The basis for fire hose
calculations are the size of the hose, the
amount of water flowing, the length of the
hose lay, the age of the hose, and the
condition of the lining.
Fire Service Hydraulics
• Formula’s
– Friction Loss = Coefficient x Flow Rate In Gallons
Per Minute/100 (squared) x Hose Length In
Feet/100
FL = C x Q² x L
FL=C·Q²·L
• FL = Friction loss in hose
• C = Coefficient, a given number for
each size of hose
• Q = GPM flow through the hose
• L = Hose length
FL = C x Q² x L
C
A given
number
?
Q²
Know or
decide
x
?__
100
L
See, know,
or decide
x ?__ =FL
100
Fire Service Hydraulics
• Friction Loss Coefficients
1 3/4” - 15.5
2 1/2” - 2.0
3” - .80
4” - .20
GPM = 29.7 x d² x NP
GPM
= discharge in gallons per minute
29.7
= a constant
d²
NP
= diameter of the tip in
inches/squared
= nozzle pressure in psi