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100 Cards in this Set
- Front
- Back
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What is a positive displacement pump? pg. 265 |
A positive action takes place where all water and air are forced out of the pump body with each operating cycle. |
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How does a centrifugal pump create pressure? pg. 265 |
- Depends on velocity of the water produced by centrifugal force to provide pressure. - It does not use positive action to force air/water through. |
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Positive displacement pumps can pump what? pg. 266 |
Air |
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What are the two basic types of positive displacement pumps? pg. 266 |
Piston and rotary |
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How does a piston pump work? pg. 266 |
- Piston in a chamber that travels up and down. - Piston forces air out of the discharge outlet and continues the cycle until all the air is out of the pump. - Atmospheric pressure then pushes water up the intake hose into the pump. |
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What is a single acting piston pump? pg. 266 |
- forward stroke causes water to be discharged - return stroke causes the pump to fill with water again - not very usable fire stream, no water flowing during the return stroke, surges of water |
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What is a double acting piston pump? pg. 267 |
- both receives and discharges water on each stroke of the piston - still has pressure surges with two periods of no flow |
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The output capacity of piston pumps are determined by what? pg. 267 |
The size of the cylinder and the speed of the piston travel |
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What are the two types of rotary pumps? pg. 268 |
rotary gear rotary vane |
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Characteristics of a rotary gear pump? pg. 268 |
- consists of two gears that rotate in a tightly meshed pattern inside a water tight case. - gears form watertight and airtight pockets as they turn from the intake to the outlet. |
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The total amount of water a rotary gear can pump is dependent on what? pg. 268 |
Depends on the size of the pockets in the gears and the speed of the rotation. |
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Rotary gear pumps are made out of what? pg. 269 |
- bronze and another soft metal in the gears - strong alloy such as cast iron used for the pump casing - drive gear usually made of steel with inserts of bronze (to handle the torque) |
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Characteristics of rotary vane pump? pg. 269 |
- most common pump used to prime centrifugal pumps - as rotor turns, vanes press against the housing by centrifugal force - air being evacuated from the intake side causes reduced pressure & water is forced into the pump by atmospheric pressure |
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What is a centrifugal pump? pg. 270 |
- imparts velocity to the water and converts it to pressure within the pump itself - a nonpositive displacement pump |
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What is the principle of operation for centrifugal pumps? pg. 270 |
- a rapidly revolving disk tends to throw water introduced at its center toward the outer edge of the disk - velocity created by the spinning disk is converted to pressure by confining the water within the container |
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Fundamentally the centrifugal pump consists of what two parts and what do they do? pg. 270 |
1. An impeller - transmits energy in the form of velocity to the water. 2. A casing - collects the water and confines it in order to convert the velocity to pressure; then directs the water to the discharge of the pump |
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How fast does the impeller rotate? pg. 270 |
generally from 2,000 to 4,000 rpm |
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What is the eye of the impeller? pg. 270 |
Where water from the intake is introduced into the pump. |
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The volume capability if dependent on what? pg. 270 |
- the size of the eye - the larger the eye, the greater the flow capacity |
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After water enters the eye of the impeller, what occurs next? pg. 270 |
Water comes in contact with the vanes of the impeller and is thrown by centrifugal force to the outside of the impeller. |
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What does the shroud do? pg. 270 |
Shrouds confine the water in its travel after the vanes throw it. - increase the velocity for a given speed of rotation |
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Why is the impeller mounted off center in the casing? pg. 271 |
This placement creates a water passage that gradually increases in cross-sectional area as it nears the discharge outlet of the pump. |
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What is the volute? pg. 271 |
The water passage that gradually increases in cross-sectional area as it nears the discharge outlet of the pump. - The increasing size of the volute is necessary because the amount of water passing through increases as it approaches the discharge outlet |
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What are the three main factors that influence a centrifugal pumps discharge pressure? pg. 271 |
1. The amount of water being discharged (greater the volume of water flowed, lower the discharge pressure) 2. Speed at which the impeller is turning (greater the speed, greater the pressure) 3. Pressure of water when it enters the pump from a pressurized source (hydrant, relay, etc) |
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Doubling the speed of the impeller results in what? pg. 272 |
Four times as much pressure. |
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Will water flow through a centrifugal pump if the impeller is not turning? pg. 272 |
Yes. If water is supplied to the eye under pressure, the impeller increases both the velocity of the water and the corresponding pressure buildup in the volute. |
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What are the two basic types of centrifugal pumps? pg. 272 |
1. Single-stage 2. Two-stage |
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What is Newton's Third Law of Physics? pg. 272 - 273 |
For every action, there is an equal and opposite reaction. |
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What was designed to minimize lateral thrust of large quantities of water entering the eye of the impeller? pg. 273 |
Double suction impeller- takes water in from both sides, the reaction being equal and opposite cancels the lateral thrust. |
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Characteristics of multi-stage centrifugal pump? pg. 273 |
- has an impeller for each stage mounted within a single housing (usually mounted on a single shaft driven by a single drivetrain) - capable of connecting the stages in series for maximum pressure or in parallel for maximum volume by use of a transfer valve |
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What occurs when pumping in parallel? pg. 273 |
- volume position - each impeller takes water from a source and delivers it to the discharge - each impeller can deliver its rated pressure while flowing 50% of the rated capacity |
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What happens when you increase the discharge pressure of the pump above the rated pressure? pg. 274 |
Results in a decreased volume of water being discharged. |
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What occurs when pumping in series? pg. 274 |
- pressure position - all the water from the intake manifold enters the first eye - first stage increases pressure and discharges 50 - 70% of the volume capacity through the transfer valve into the second eye - second impeller increases the pressure and delivers the water at a higher pressure into the pump discharge port |
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When pumping in series, water is limited by what? pg. 274 |
Water is limited to the amount that one impeller can supply. |
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What is changeover? pg. 274 |
The process of switching between pressure and volume (switching the transfer valve). |
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Per IFSTA, what is the recommended maximum pressure that a transfer valve be operated at? pg. 275 |
Not to exceed 50 psi. |
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What is the maximum flow rating of a pump per IFSTA? pg. 274/276 |
150 psi at draft. |
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Why does IFSTA state it is better to have the pump in parallel (volume) than in series (pressure) mode? pg. 276 |
- in parallel, the pump can supply 100% of the rated volume capacity at 150 psi @ draft. - in series, can deliver more pressure, but may not be able to provide the necessary volume for attack lines. |
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Why are clapper (check) valves essential in multi-stage pumps? pg. 276 |
- if they stick open/closed, the pump will not operate properly in pressure mode. - allows water to escape back into the intake, water will churn through the pump instead of building up pressure |
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Why must a close tolerance be maintained between the pump casing and the hub of the impeller (pump packing)? pg. 276 |
Because the pressure in the volute is much higher than that in the intake side of the pump at the eye of the impeller (to help prevent water from escaping back into the intake). - opening is usually limited to .01 inch or less - increase in opening lessens the pumps effectiveness. |
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What is the first indication that wear is becoming a problem to the packing? pg. 276 |
When increased engine rpm is required to pump the rated capacity in pump tests. |
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What is a thermal relief valve? pg. 278 |
Newer centrifugal pumps are equipped with this valve that opens to allow overheated water to circulate between the pump and the main tank or into the atmosphere. |
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How can a driver/operator check the pump temperature and what can he do about it? pg. 278 |
- place his hand on the direct pump intake pipe of the pump, if it is warm to touch the pump is warm. - should open a discharge or circulator valve to move water or if pump is not going to be used for a while, disengage the pump. |
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What are packing rings and what are they made out of? pg. 278 |
- used to make a seal and prevent air leak that could interfere with drafting, between the shaft and the pump casing. - made of rope fibers impregnated with graphite or lead/ ceramic or mechanic seals (non-adjustable) |
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What is a lantern ring? pg. 278 |
- a spacer, supplied with the packing to provide cooling and lubrication - where the packing rings come into contact with the shaft |
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What happens if the packing is too tight or too loose? pg. 279 |
tight - water is not allowed to flow between the packing and the shaft, excessive heat buildup results. loose - indicated by excessive amount of water leaking from the pump during operation. Will also allow air to leak and affect pumps ability to draft. |
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Characteristics of auxiliary engine-driven pumps? pg. 280 |
- powered by gasoline or diesel, independent of an engine used to drive the vehicle - offer maximum amount of flexibility - can be mounted anywhere on apparatus - ideal for pump and roll operations (mobile attack) - generally 500 GPM or less |
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Characteristics of a PTO (Power Take Off) Drive? pg. 281 |
- pump is driven by a driveshaft that is connected to the PTO on the chassis transmission. - pump gear must be mounted in a location that allows for a minimum of angles in the driveshaft. - mounted on the side of the transmission |
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Characteristics of front mount pumps? pg. 281 - 282 |
- pump mounted between bumper and the grill - driven by a gear box connected by a universal joint shaft to the crankshaft - gear box uses step up ration, causes impeller to turn faster than the engine - chassis should have a front mount PTO |
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Disadvantages of front mount pumps? pg. 282 |
- pump & gauges are exposed to temperatures being mounted on bumper - can obstruct air flow to vehicles radiator - vulnerable to a collision |
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When using a PTO to conduct pump and roll/mobile attack, how should the driver/operator monitor their speed? pg. 281/282 |
Driver/operator should go off the pressure gauge of the pump and not use the speedometer. |
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Characteristics of Midship pumps? pg. 283 |
- pump mounted laterally across the frame behind the engine and transmission - split shaft (transfer case) located in the drive line between transmission and the rear axle supplies power - power is diverted from rear axle to fire pump |
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On midship pumps, when placed into pump, most speedometers should read what? pg. 283 |
With the engine idling and the pump engaged, most speedometers read between 10 to 15 mph. |
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Characteristics of Hydrostatic pumps? pg. 284 |
- driven by a shaft from the front of the vehicles engine that turns a hydraulic pump that drives a midship or rear mounted centrifugal pump of up to 1,000 GPM - can be used stationary or mobile (pump&roll) |
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Advantages/disadvantages of rear-mount pumps? pg. 285 |
Adv: helps provide a more even weight distribution on the apparatus chassis - more compartment space Disadv: driver/operator may be more directly exposed to oncoming traffic than other positions |
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What are the primary components of the piping system? pg. 285 |
- intake piping - discharge piping - pump drains - valves |
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Characteristics of pump piping and valves? pg. 285 |
- must be of a corrosion-resistant material - cast iron, brass, stainless steel or galvanized steel, may have rubber hoses - must be able to withstand hydrostatic test of 500 psi - run as straight as possible, minimum bends/turns |
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What are the two primary ways that water may enter the fire pump? pg. 286 |
1. through piping that connects the pump and onboard water tank 2. piping that is used to connect the pump to an external water supply |
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What do check valves do? pg. 286 |
- prevents damage to the tank if tank to pump line inadvertently opens and water is being supplied to pump under pressure (relay) |
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Where is the primer located? pg. 286 |
- tapped into the pump at a high point - on suction side of the impeller eye and a valve (priming valve) is used |
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Where are intake lines located in relation to the pump? pg. 286 |
- All intake lines to a centrifugal pump are normally located below the eye of the impeller - no part of the piping is above this point - exception may be the tank to pump line where water is moving under natural pressure of gravity |
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Per NFPA 1901, what is required for discharge piping? pg. 288 |
Enough 2 1/2" inch or larger discharge outlets must be provided in order to flow the rated capacity of the fire pump. |
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Per IFSTA, all fire apparatus with a rated pump capacity of 750 GPM or greater must be equipped with what? pg. 288 |
As a minimum, at least two 2 1/2" inch discharges. - pumps rated less than 750, requires only one 2 1/2" inch discharge |
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Discharges of 1 1/2", 1 3/4" and 2" inch for handlines are supplied by what size piping? pg. 288 |
Supplied by at least 2" inch piping. |
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Discharges are usually equipped with what? pg. 288 |
- locking ball valves - should always be kept locked when they are open to prevent movement - should be designed to easily operate at pressures of up to 250psi |
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What is a tank fill line? pg. 289 |
- aka pump to tank line - from the discharge side of the pump - allows tank to be filled |
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NFPA 1901 requires what size tank fill lines? pg. 289 |
- tank less than 1,000 GPM, tank fill line at least 1" inch in diameter - tank of 1,000 GPM or greater, tank fill line at least 2" inches |
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On apparatus without a thermal relief valve, what can be used to help prevent overheating? pg. 289 |
- opening the tank fill line can help circulate water through the pump to help prevent overheating when no lines are flowing - in a two stage pump, tank fill line comes off the first stage pump, so second stage can still overheat |
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What is a circulator valve? pg. 289 |
- connected to the discharge side of the pump and enables water to be dumped into the tank or outside the tank on the ground |
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What is a booster line cooling valve? pg. 290 |
- aka "bypass" - serves same function as circulator valve, diverting portion of the water into the tank |
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What are the most common types of valves? pg. 290 |
- ball type valve - push/pull handles (T-handles) or quarter turn handles |
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What type of valves are most commonly used on large diameter intakes and discharges? pg. 291 |
- gate or butterfly valves - gate - most common operated by handwheel - butterfly - most common by quarter turn handles |
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NFPA 1901 requires what of all valves on intakes or discharges that are 3" inches or greater? pg. 291 |
- To be equipped with slow acting valve controls - prevents movement of fully open/closed in less than 3 seconds - reduce risk of water hammer |
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Where are drain valves located? pg. 291 |
- on the line side of the control valve - to relieve pressure from the hoseline after the discharge valve and nozzle have both been closed - @ the lowest point on the pump & lowest point on each lineNf - also helpful to drain the line in freezing temperatures |
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What is a bleeder valve? pg. 292 |
- on the line side of the intake valve - air can be forced out of the hose through the bleeder as the line fills with water - help prevent air from entering the pump and losing prime |
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NFPA 1901 requires some type of pressure control device to be a part of the pumping system and to do what? pg. 293 |
- must operate within 3 to 10 seconds after the discharge pressure rises - must not allow the pressure to exceed 30 psi above the set level |
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What are the two basic concepts for pressure relief valves? pg. 294 |
1. Those that relieve excess pressure on the discharge side of the pump 2. Those that relieve excess pressure on the intake side of the pump |
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What is the main feature of a relief valve? pg. |
It is sensitive to pressure changes and has the ability to relieve excessive pressure within the pump discharge |
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What are intake pressure relief valves and what are the two basic kinds? pg. 295 |
- Intended to reduce the possibility of damage to the pump and discharge hoselines caused by water hammer when valves/nozzles are closed too quickly. - Two basic kinds: 1. One that is supplied by the pump manufacturer and is an integral part of the pump intake manifold. 2. Added on device that is screwed onto the pump intake connection |
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What are intake relief valves generally set to? pg. 295 |
Be set to open when the intake pressure rises more than 10 psi above the desired operating pressure. |
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What does a pressure governor do? pg. 296 |
- Regulates the power output of the engine to match pump discharge requirements - mechanical or electronic, pressure activated to adjust the engine throttle |
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The speed of the impellers determines what? pg. 296 |
Speed of the impeller determines the pressure and the engine speed determines the speed of the impellers. - reduce the engine speed to reduce the pressure |
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How does the pressure governor work? pg. 296-297 |
- hoseline is shut off, increase in pressure travels through the pipe from the discharge into the cylinder - moves the piston from set position, causes carburetor control linkage to adjust the butterfly valve and reduce the engine speed - hoselne opened, reverse occurs and piston moves back to increase engine speed |
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How does a piston assembly governor work? pg. 297 |
- speed of engine is controlled by a governor assembly - assembly fits onto the carburetor (gasoline engines) or throttle link (diesel engines) and reduces or increases the engine speed under the control of a rod connected to a piston in a water chamber. |
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How does a pressure transducer work? pg. 298 |
- is a pressure sensing element, connected to the discharge manifold - when necessary, the element changes the throttle setting by adjusting the amount of fuel supplied to the engine, bringing the pump to desired pressure - many newer apparatus equipped with electronic governors |
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How does the cavitation protection mode work on a pressure transducer? pg. 298 |
- returns the engine to idle when the intake pressure drops below 30 psi. |
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Primers fall into what three categories? pg. 299 |
1. displacement - rotary vane or gear, vane requires higher rpm that gear 2. exhaust - uses engine exhaust to create vacuum 3. vacuum - simplest type of primer, uses vacuum already present in intake manifold. |
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NFPA 1901 requires what controls and instruments to be located on the pump panel? pg. 300 |
- master pump intake indicating device - master pump discharge pressure device - pumping engine tachometer - pumping engine coolant temperature - pumping engine oil pressure - voltmeter - pump pressure controls (valves) - engine throttle - water tank to pump valve - tank fill valve - water tank level indicator |
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What are the two primary gauges for determining water pressure entering and leaving the pump? pg. 302 |
master intake - "Vacuum or compound gauge" master pump discharge pressure gauge |
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What does the master intake gauge do? pg. 302 |
- vacuum (negative) or compound gauge (positive) - intake side of pump - capable of measuring both positive (0 to 600 psi) and negative (0 to 30" inches of mercury) |
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What does the master pump discharge pressure gauge do? pg. 303 |
- calibrated to measure 600 psi - registers the pressure as it leaves the pump but before it reaches the gauges for each individual discharge line |
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What does the tachometer do? pg. 303 |
- records the engine speed in revolutions per minute (rpm) * a gradual increase in the rpm's required to pump the rated capacity indicates wear in the pump and a need for repairs. |
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What does the engine coolant temperature indicator show? pg. 304 |
- the temperature of the coolant in the engine that powers the fire pump |
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What does the pumping engine oil pressure indicator show? pg. 304 |
- shows if an adequate supply of oil is being delivered to the critical areas of the engine that is powering the fire pump - not a measure of the oil level in the crankcase (although, if oil level in crankcase drops too low, it is impossible to maintain proper pressure) |
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What does the voltmeter show? pg. 304 |
Provides an indication of battery condition and alternator output by measuring drop in voltage as some of the more demanding electrical devices are used (primer, etc) |
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What does the pumping engine throttle do? pg. 305 |
- on pump panel - used to increase/decrease the speed of the engine that is powering the fire pump - most common is knob that turns ("vernier") |
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What is a vernier? pg. 305 |
Throttle knob |
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What is the primary purpose of auxiliary cooling devices and what are the two types? pg. 307-308 |
- to control the temperature of coolant in the apparatus engine during pumping operations - marine type and immersion type |
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How does a marine type auxiliary cooler work? pg. 307 |
- inserted into one of hoses used in the engine cooling system so that the engine coolant must travel through it as it circulates through the system - cooler has many tubes, surrounded by a water jacket that is connected to discharge of the pump - coolant runs through the tubes, water from pump passes around the tubes to cool |
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How does an immersion type auxiliary cooler work? pg. 308 |
- opposite of a marine type cooler - radiant coolant passes through the body of the cooler - water from the fire pump passes through a coil or some type of tubing within the body |
