CVFD Training – Pump Operations SFFMA Training Objectives 24-01.01 – 24-01.02.

transcript

CVFD Training – Pump Operations

SFFMA Training Objectives24-01.01 – 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 HammerWater 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• 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

• 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

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) Incoming Pressure– 2) Speed of the impeller– 3) 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)

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

• 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.– Water should drip, not run from packing gland

• New “Ceramic” packing– Must have temperature relief valve to protect

ceramic disk

CavitationWhat 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 back-up

to the transfer switch

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.

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

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 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.

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.

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.

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

• Quality version

• Detroit Diesel Fire commander

• On all E-One Fire Apparatus

Movie Time“Pressure Governor Video”

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

• 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• 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

• Booster tanks• Positive pressure sources– 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 AvailableWhen 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 = (70 - 63)(100) 70

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

Fire Service HydraulicsWater Available Table

Percent Decrease Water Available0 - 10% 3 x Amount11 - 15% 2 x Amount16 - 25% Same AmountOver 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 pre-incident planning activities.

• There are situations when pumpers supporting sprinklers or standpipes must give priority to other fire apparatus (aerial apparatus).

• 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:– 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 available2) Type of water available3) 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

• 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 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.

TANDEM PUMPING SET-UP(HIGH-PRESSURE RELAY)

E 45E 7

60 STORY BLDG.

E/OE/O

Supplemental Pumping

E70 E52

Supplemental Pumping

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, 0.434 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 100 100

• Friction Loss Coefficients

1 3/4” - 15.52 1/2” - 2.0

3” - .804” - .20

GPM = 29.7 x d² x NP

GPM = discharge in gallons per minute29.7 = a constantd² = diameter of the tip in

inches/squaredNP = nozzle pressure in psi

CVFD Training – Pump Operations SFFMA Training Objectives 24-01.01 – 24-01.02.

Documents