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127 Cards in this Set
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- Back
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What are the three sources of water supply to the pump?
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onboard, static, pressurized
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IFSTA recommends that the apparatus wheels be chocked when?
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every time the apparatus is stopped with the engine running and the driver/operator exits the cab
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Tests have indicated that the apparatus may override the parking brake system at engine speeds as low as what?
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1300rpm
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Some midship pump apparatus will not have a reading of above 0mph when in pump why?
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the speedometer reading is taken off the rear of the transfer case
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If the pump has been drained of dater it will be full of air. The air has to be forced out of the pump by the water as it enters before discharge presser can build. In this case at least how can you evacuate air other than the primer?
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at least one of the discharge valves or tank tank fill line must be opened before air can escape and the pump can fill with water
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Operating at a negative pressure (pulling vacuum) from a fire hydrant is dangerous why?
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because it increases the possibility of damage to the fire pump due to cavitation
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To avoid possible damage to the water system, do not allow the incoming pressure from a hydrant to drop below what?
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20psi
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In rare instances it may be necessary to reduce the intake pressure below 20psi, but the intake pressure should never be allowed to drop to what?
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0
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Is the hydrant closest to the fire always the best?
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no
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In order to elect the best hydrant a through knowledge of what is required?
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the water system
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The best hydrants are located on what type of water mains?
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large man its that are interconnected in a grid patten
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The worst type of hydrant to connect to are what?
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dead end mains
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What type of hydrant is more susceptible to sedimentation and deterioration build up?
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dead end mains because they don't have sufficient flow to prevent them from becoming partially clogged with sediment and encrustation
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Subjecting dead-end mains to extraordinary flow requirements during pumping operations may cause what?
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materials to be drawn into the pump intake screen, reducing flow into the pump and causing cavitation
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What is a forward lay?
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stopping at the hydrant, dropping the end of one or more supply lines at the hydrant, and proceeding to the fire location?
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What is a class AA, A, B, and C hydrant color and rpm?
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AA - Light blue - 1500or greater
A - Green - 1000-1499 B - Orange - 500-999gpm C - Red- less than 500gpm |
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What NFPA is for, Recommended Practice for Fire Flow Testing and Marking of Hydrants?
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291
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Only use gate valves on what type of hydrants?
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dry barrel (frost proof)
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When using 2-1/2 or 3" hose lines to supply the pumper directly off hydrant pressure it is recommended that the hose lines be no longer than what?
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300ft
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When would the 300ft maximum rule not be followed?
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using large diameter hose, also it may be extended somewhat if the hydrant is on a special ugh pressure main
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What is a reverse lay?
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the hose is laid from the fire to the water source
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Why use a reverse lay?
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if the pumper must go to the fire location first for a size up, it is also the most expedient way to lay hose if the apparatus that lays the hose must stay at the water source, such as when drafting or boozing hydrant pressure to the supply line
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Reverse lay has become a standard when?
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when using medium diameter hose as a supply line
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Reverse lay is the most direct way to do what?
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supplement hydrant pressure and perform drafting operations
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When the first pumper arrives at a fire and must work alone for an extended period of time what time of lay is used?
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reverse lay
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THe tank to pump should always be in what position when switching to an external water supply?
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closed
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It is generally recommended that the hydrant valve be opened how far?
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all the way, then closed one quarter turn to relieve the strain on the valve stem and internal components
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While observing the master intake gauge do not increase the throttle further in danger of cavitation when?
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when the intake drops below 20psi
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It is necessary to keep the pump from overheating by ensuring a continued minimum flow. What are some methods to prevent overheating of the pump?
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-pull some of the booster line off the reel and securely tie off the nozzle to a solid object and allow it to flow
-open a discharge drain valve -partially open the tank fill valve -use a bypass or circulator valve |
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When a pumper is connected to a hydrant and is not discharging water, the pressure shown on the intake gauge is what?
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static pressure
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When the pumper is discharging water, the intake gauge reading is?
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residual pressure
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Per IFSTA what is the assumed flow rate for an 1-3/4 line?
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175gpm
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The last turn in a dry barrel hydrant opens the drain. How do you know the drain is actually open and that you don't need to manually drain/pump the hydrant?
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cover an outlet with the palm of your hand, you should fell a slight vacuum
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The amount of friction loss is proportional to what?
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the amount of water moving through it
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What is an additional factor in pressure loss when drafting?
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the inertia of water. as the water begins to move through the pump a certain amount of energy is consumed in getting the water art rest to begin to move and increase its velocity sufficiently to supply the amount of water needed
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For a 1500gpm pump the max suction hose size and max number of suctions lines is what?
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6" max suction hose with max number of lines 1
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A pumper that is normally rated at 750gpm with a 4-1/2" supply suction hose is being supplied with a 5-inch hose, the capacity if all other factors remain the same of the pump is now what?
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820gpm
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The totral pressure available to overcome all pressure losses when drafting is limited to what?
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14.7psi, atmospheric pressure
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Atmospheric pressure decreases how much for every 1000ft of elevation gain?
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0.5psi
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The max vacuum that most pumps develop is what?
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22inches of mercury
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If an attempt to increase the vacuum beyond the intake limit is made what can it cause?
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cavitation of the pump
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What is cavitation?
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the condition where, in theory, water is being discharged from the pump faster than it is coming in
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What is cavitation described as?
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the pump running away from the water
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When does cavitation occur?
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when air cavities are crested in the pump or bubbles pass through the pump. they move to the point of highest vacuum into the pressurized section where they collapse or fill with fluid
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What is a scientific explanation of cavitation?
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as the pressure drops below atmospheric pressure the boiling point of water drops to the point that liquid changes to a vapor and creates a bubble of water vapor or steam. as the vapor passes through the impeller of the pump, the pressure increases, the vapor condenses, and waster rushes in to fill the void
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What things affect the point at which cavitation begins?
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temperature of water, height of lift, the amount of water being discharged
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What are indications that a pump is caveating?
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hose streams will pulsate, the pressure gauge on the pump will fluctuate, a popping or sputtering should may be heard as water leaves the nozzle. in severe cases the pump will be noisy, sounding like gravel is passing through it
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What is the best indication of cavitation?
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the lack of reaction on the pressure gauge to changes in the setting of the throttle
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When the pump is discharging all of the water that the atmospheric pressure or other pressure source can force into the intake what is happening?
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cavitation
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When water is being discharged from the pump faster than it can be taken in, the increasing rpm does not do what?
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increasing pump rpm will not increase discharge pressure when there is no more water available to be supplied
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Cavitation often results when a pump has been equipped with what?
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inadequate piping from the water tank for the amount of flow
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Cavitation damage can be even more severe when?
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when operating at relatively high pressure
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Selecting a drafting site is dictated by what factors?
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amount of water, type of water, accessibility of water
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What is the most important factor in the choice of draft site?
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amount of water
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In order for a pumper to approach its rated capacity using traditional strainer, there should be a minimum of how many feet of water over the strainer?
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2ft
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When drafting what can cause a whirlpool to form?
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rapid movement of water when the strainer is not 2ft under water
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What can be used to prevent a whirlpool effect?
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a wooden board, capped plastic bottle or beach ball may be placed above the strainer
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What is a disadvantage to using a floating strainer?
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it can take water in on only one side
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Water below or above what temp may adversely impact the pumps ability to reach capacity?
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blow 35 degrees or above 90 degrees F
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In freezing climates ater several feet blow the surface may be how much warmer?
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5-10 degrees
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Where is warmer water found?
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near discharges of power plant cooling towers, and should be avoided being used
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Pumping what type of water can be harmful to the pump?
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untreated, non potable water
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What kind of water is common in the vicinity of coal mines
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sulfur
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After using unpotable water in the pump what should you do?
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flush it with clean water
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What type of water should you avoid filling the tank with?
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unpottable
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What can be added to the water when flushing the pump?
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antifreeze
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What is the most common type of contamination in water when drafting?
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dirty or sandy water
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Sand acts as an abrasive the the area between what in the pump?
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the clearance rings and the hub of the impeller
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Abrasion quickly increases the spacing in the pump to an intolerable amount which causes what?
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increased slippage from the discharge back into the intake and reduces the capacity of the pump
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As dirty water passes through the pump it is forces into where by what?
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the packing by discharge pressure
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When the packing becomes contaminated by dirt what happens?
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it can no longer be adjusted to form a good seal, this causes air leaks at the intake side of the pump and reduces its ability to draft
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When drafting, as the amount of lift increases what occurs?
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elevation pressure increases, less friction loss can be overcome, capacity of the pump is decreased
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All fire pumps meeting NFPA and Underwriter/s Laboratories requirements are rated to pump their capacity at what?
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10feet of lift
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For effective operation the max lift considered reasonable for most departments is what?
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about 20ft
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At 20ft of lift the amount of water that can be supplied is only about what of the rated capacity of the pump?
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60percent
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What is more important, low hose length or low lift?
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it is important to keep lift as low as possible. it would be better to lay out an extra 100ft of supply line and set up in lower lift
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Routing hard intake hose over a fence or railing that is higher than the level of the pump intake may do what?
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leave a highpoint that traps air in the hose
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If drafting on a two stage pump what should the pump be set in when priming?
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parallel (volume)
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Before you begin priming make sure what?
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all drains and valves are closed and that unused intake and discharge openings are capped to make the pump as airtight as possible
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Most priming pumps are intended to work best when the engine is set between what rpm?
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1000 and 1200rpm
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When the master gauge registers a vacuum reading it should be what per foot of lift?
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1inch for each 1foot of lift
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As the primer operates the vacuum reading increases and what forces whiter into the hard intake hose?
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atmospheric pressure
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Priming action should not be stopped until when?
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all the air has been removed and the primer is discharging a steady stream of water
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In drafting, as the pump fills with water a pressure indication shows on what?
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the master discharge gauge
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The entire priming action typically requires how long?
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10-15sec
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When using no more than 20ft of hard intake hose lifting a max of 10 vertical ft it should not take longer than what to get a prime?
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30sec, 45 on pumps larger than 1250gpm
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If a prime has not been achieved in 30secs do what?
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stop priming and check to find out what the problem is
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What is the most common cause of inability to prime?
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an air leak that prevents the primer from developing enough vacuum to successfully draft water
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What are the most common source of leaks?
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open drains and valves
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What is another name for the bypass valve?
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booster cooling valve
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Other than air leaks what are some other things that can prevent being able to hold a prime when drafting?
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insufficient fluid in the priming reservoir, engine speed is too low, lift is too high, a high point in the hard intake hose is creating an air pocket
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When drafting, after getting a prime increased throttle pressure is needed to boost the pressure to what?
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between 50 and 100psi
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After getting a prime when drafting open the discharge slowly, if pressure drops below 50psi do what?
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stop for a moment and let it stabilize, if the valve is opened too quickly it can allow air to enter the pump and cause it to loose its prime. if pressure keeps on dropping open the primer to eliminate any air that may be trapped
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The vacuum to initially prime the pump comes from what?
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the primer
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Once the pump begins to operate the primer is no longer used. At this point what maintains the vacuum?
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the movement of water
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When no water is being discharged in a drafting situation even the smallest air leak may result in loss of vacuum. How can this be prevented?
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the same methods as for preventing overheating prevents this, including discharge a booster line back into the static water source with the booster line tied down to some immovable object
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If the priming device fails to operate it may be possible to use what to achieve a prime?
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the vehicles water in the tank, this can sometimes be done by using the tank water to fill the pump and intake hose sufficiently to allow a prime
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What is the most demanding type of pump operation?
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operating from draft
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What is a signal that another pumper should be used for drafting?
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any deviation from normal engine temperature
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What are the problems that can occur when operating from draft?
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air leak on the intake side of the pump, whirlpool allowing air to enter the pump, air leakage due to defective packing in the pump
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What are the most common problems when drafting?
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air leaks on the intake side of the pump
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How do you know if air is coming into the pump with water when drafting?
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discharge pressure gauge begins to fluctuate with a corresponding loss of vacuum on the intake gauge
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If there is an air leak when drafting where is the first place to look?
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the intake hose
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What can prevent a whirlpool when drafting?
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a beach ball or other floating object above the strainer
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What type of strainer should be used in shallow water where whirl pooling is a problem?
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floating dock strainer
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A gradual increase in the vacuum reading with no change in flow rate while drafting is a sign of what?
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possible blockage occurring
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Other than objects externally what can cause drafting intake hose to develop blockage?
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the inner liner can become detached and collapse on itself
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Exceeding the capacity of the pump leads to what?
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cavitation
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Upon arrival at a sprinklered property preparations should be immediately made to what?
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supply the fdc
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What do the sprinkler fire department connections consist of?
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at least two 2-1/2"" female connections, or one large diameter sexless connection that is connected to a clappered inlet. water flows through the valve to a check valve
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A minimum of what should be connected to the fdc?
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2 2-1/2 hoselines
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It is a general rule that one, how many rpm rated pumper should supply the fdc for every how many sprinklers that are estimated flowing?
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one 1000gpm pumper for every 50heads
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In most cases what should be done before pumping into the sprinkler system?
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confirm the presence of fire
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If an unknown amount of sprinklers are going off the pump pressure should be what?
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150psi
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Smoke getting cooled by the water from they sprinkler system does what to the smoke?
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causes it to loose its buoyancy, hindering size-up because of low visibility
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In a sprinklered building control valves should be opened except when?
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in the case where it is known that the building or area has been undergoing construction or renovation affecting the sprinklers, opening it could cause a loss of water to the system
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Firefighters assigned to open control valves should carry what?
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flashlight and radio
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Standpipes are used for what?
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to speed fire attack in multistory buildings with large floor areas
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When should fire personnel use house or standpipe lines?
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not unless a hose testing program similar to the one used to test all fire department hose is implemented
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House lines are intended to be use by who?
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building occupants, not firefighters, firefighters should bring their own attack lines when they enter a properly protected with standpipes
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Dry pipe standpipe systems get their water from where?
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supplied from a pumper that attaches to the standpipe fdc
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Standpipe fdc should be clearly identified why?
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to prevent confusion between sprinkler and standpipe connection
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Do wet standpipe systems have an fdc?
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yes, they should be used to supply water under pressure to suppliant the system's water supply
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Pump discharge pressures in excess of what are not encouraged in standpipes?
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200psi, unless the standpipe has been designed to withstand higher pressures
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When a standpipe system is known to be equipped with pressure reducing valves the election pressure used must be based on what?
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the total height of the standpipe or the zone being used
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If a standpipe fire department connection is totally unusable because of vandalism what can be done?
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the riser at the first floor can be charged at the first floor level by attaching a double female to the valve at the first floor, or a ladder pipe can be raised to the desired floor and used as an exterior standpipe
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As a last resort what can you do if the standpipe is not available?
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supply how can be laid up the interior stairwell to take the place of the standpipe
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