CVFD Training – Pump Operations

CVFD Training – Pump Operations
SFFMA Training Objectives –

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= ·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.

This surge is called 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 200 PSI x 7 = 1400 PSI or 1400 pounds of pressures returning, finding the weakest spot in the system and breaking it. This could be the pump, hose, nozzle, pump piping, supply line, or water main.

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.

[Tell any water hammer stories if you have them.]

GAUGES Master Intake gauge (Compound) Master Discharge gauge
Discharge gauge (individual gauges) Oil Pressure Voltmeter Tachometer (engine RPM) Pump overheat indicator Engine coolant temperature gauge The master intake and discharge gauges are the two primary gauges used to determine the water pressure entering and leaving the pump.

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 Commonly referred to as compound or vacuum gauge Usually calibrated from PSI positive pressure and 0-30 inches of vacuum on the negative side Obtain residual pressure with this gauge

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 May differ from individual gauge in relation to PSI, individual more reliable for specific line

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. Shows that an adequate supply of oil is being delivered to the critical areas of the engine It is not a measure of the oil in the crankcase

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 Warning indicators can be flashing lights or an audible alarm. Not standard equipment, must be ordered for pump panel. New Houston Fire Department E-1 pumpers have a TRV or Temperature Relief Valve. This valve is a “gel” type. When the gel heats to 120ºF the valve opens slowly and lets out a stream of water underneath the pumper. This assists in keeping the pump from overheating, but does not eliminate it from occurring. The gel keeps the valve from opening and closing quickly. The operator of the pump must discharge or flow water constantly to keep the pump from overheating and damaging the fire pump.

Pump Overheat Best place to check for overheat is right here
Best way to never overheat the pump is to always be moving water. Place your hand on the large intake pipe. If it is warm or not cool to the touch, then the pump is too HOT! Discharging water is the only way to cool it down. Open the tank fill valve or open a discharge and flow water on the ground.

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 Rotary Centrifugal Single, Multiple Gear
Single-stage, Two-stage, Multiple-stage

Pump Equipment Centrifugal Pump Multi-stage Pumps Cavitation
Pressure Relief Valves/Governors Positive Displacement Primers Manual Pump Shift Gauges Auxiliary Cooler Valves The pump equipment covered in this class will include the following; Centrifugal pump Pressure relief valve/governor Intake relief valve Transfer valve Positive displacement primers Manual pump shift Gauges Auxiliary cooler

Centrifugal Pump Components Impeller Eye Hub Vanes Volute Shroud
Casing

Pump Impeller Vane Impeller eye Shaft opening Shroud

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) Incoming Pressure 2) Speed of the impeller 3) Amount of water being discharged Single or Multi-Stage Maximum Discharge 150 psi plus static pressure on hydrant

Rated Capacity A pump is draft, the following show the different pressures: 150 psi (net pump pressure) 200 psi (net pump pressure) 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 50 psi net pump pressure Transfer valve found on pump panel, usually with indicator light

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.

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. New “Ceramic” 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: Cavitation:
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 has a cumulative effect. Cavitation of the pump each time it is used it will eventually eat away, or destroy the pump impeller.

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 back-up to the transfer switch

POWER TRANSFER

POWER TRANSFER Engine to wheels Engine to fire pump

Pump drives 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. On rear mount pumps – only the pump is moved to the back and not the transfer case. A second driveshaft is used from the transfer case to the pump impeller.

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

Center position is the neutral or manual pump shift position
Center position is the neutral or manual pump shift position. If a massive air leak occurs, this position exhausts air from both sides of the shift mechanism. This allows the pump to be shifted into and out of pump gear by hand.

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

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.

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.

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

“Older” priming pumps require an oil reservoir. “New” priming pumps are environmentally safe requiring no priming oil. Both make a distinctive sound when operating

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 100 PSI Can be set from 50 to 175 PSI Two types of piston intakes Harrington uses set screw to adjust setting (Allen wrench is needed) and has a chart (on the intake) to refer to when setting relief pressure. Elkhart uses 7/8 adjustment bolt to adjust setting and has to be adjusted while under pressure.

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 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.

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. PRVs send water and the excess pressure from the discharge side back to the intake side. PRVs do not respond rapidly. They may take several seconds to react.

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 Shut-Down. Do not use the Emergency button for routine shut downs, as it may break the cable or pump parts. Manual back-up throttles generally are of this type.

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. PGs can respond rapidly to pressure changes.

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

Quality version

Detroit Diesel Fire commander On all E-One Fire Apparatus

Movie Time “Pressure Governor Video”

Manual Pump Shift

Manual Pump Shift 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 Allows water from pump to cool engine
Use when temperature exceeds normal level Close when temperature returns to normal Keep in closed position This valve allows water from the pump to be diverted to decrease the engine coolant temperature. The water runs through a separate set of coils, without mixing with the fluid in the radiator, and then returns to the pump. If the temperature exceeds normal recommendations, or a warning light/buzzer is activated, the engine must be cooled immediately. This is accomplished by opening the auxiliary cooler valve located on the pump panel. Once the temperature has returned to normal, the valve should be closed. If the device has to be used, notify the incident commander and mechanic. This valve should be carried in the closed position during normal operations.

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 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.

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 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 Harrington Piston Intake Valve 2. Hale/E-1 MIV
3. Akron Piston Intake Valve Keystone Valve (Butterfly Valve)

Small Intake Valve 2 ½” intake valve connects directly into the large intake piping 2 ½” female swivel Intake flow capacity GPM

Water Supply

Water Supply Booster tanks Positive pressure sources Drafting
Hydrants and other pumps Drafting

Booster Tank 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 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.

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

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 = ( )(100) 70 (7)(100) = 700 = 10 psi drop

Water Available Table Percent Decrease Water Available 0 - 10% 3 x Amount % 2 x Amount % Same Amount Over 25% Less than is being delivered

Elevation Pressure Water exerts a pressure of 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 pre-incident planning activities. There are situations when pumpers supporting sprinklers or standpipes must give priority to other fire apparatus (aerial apparatus). For test purposes: The answer in RED one to choose. To stay alive in the real world get away from the building. Your department may have a set S.O.P.

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

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: Sprinkler:
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 Unusable due to vandalism
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

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 Maximum Lift Dependable 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. Some textbooks state a maximum lift of 20 feet.

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 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. Using front or rear intakes will cause a loss of up to GPM.

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 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. Used to be used when the largest pumps were 500 and 750 GPM.

DUAL PUMPING SET-UP (HIGH-VOLUME SET-UP) E 45 E 7

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.

(HIGH-PRESSURE RELAY)
TANDEM PUMPING SET-UP (HIGH-PRESSURE RELAY) E 7 E/O E/O E 45 60 STORY BLDG.

Supplemental Pumping L93 E61 E70 E52
Either the hydrant supply engine can supply both lines, or one line each from two different engines (supplemental pumping). The supply engines should have dual lines from the hydrant for maximum water supply flow. The 6” soft suction and a 4” line convert from the 2 1/2” hydrant outlet. E70 E52

Supplemental Pumping E70 L 93 E61 E52
Either the hydrant supply engine can supply both lines, or one line each from two different engines (supplemental pumping). The supply engines should have dual lines from the hydrant for maximum water supply flow. The 6” soft suction and a 4” line convert from the 2 1/2” hydrant outlet. 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 from closing a valve or nozzle too quickly!

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.

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.

Negative Pressure - an area with a pressure less than that of the atmosphere; when calculating engine pressure and pumping to an area lower than the pump, a “negative” pressure will have to be added to the equation in order to correctly figure the engine pressure.

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

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

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

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, psi is gained

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.

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

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 in all directions. (fire pump)

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.

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.

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 Q² L A given Know or See, know,
number decide or decide ? x ?__ x ?__ =FL

Friction Loss Coefficients 1 3/4” 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 = diameter of the tip in inches/squared NP = nozzle pressure in psi

CVFD Training – Pump Operations

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