Pumping Apparatus Driver/Operator Chapter 9
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Questions and Answers

What is a key characteristic of positive displacement pumps?

  • They are self-priming (correct)
  • They operate using a piston that moves back and forth in a cylinder
  • They are only used for low volume, high pressure applications
  • They rely on centrifugal force for water discharge

    • What is the primary mechanism used by centrifugal pumps to achieve proper discharge pressure?

  • Rotary gear rotation
  • Positive action
  • Piston movement
  • Centrifugal force (correct)

    • What role do positive displacement pumps play in modern apparatus during drafting operations?

  • Priming devices to get water to the centrifugal pump (correct)
  • Acting as booster-type pumps
  • Providing high pressure streams up to 1,000 psi
  • Delivering a definite volume of air

    • What design feature characterizes rotary gear pumps?

    <p>Consist of two gears that rotate in a tightly meshed pattern inside a watertight case</p> Signup and view all the answers

    What type of pumps can provide pressures up to 1,000 psi?

    <p>Piston pumps</p> Signup and view all the answers

    In modern apparatus, where is the use of rotary pumps confined to?

    <p>Small capacity, booster-type pumps</p> Signup and view all the answers

    What type of pumps are the simplest of all fire apparatus pumps from a design standpoint?

    <p>Rotary-type pumps</p> Signup and view all the answers

    What is a key characteristic of rotary vane pumps?

    <p>They automatically compensate for wear</p> Signup and view all the answers

    What type of pump is a centrifugal pump?

    <p>Nonpositive displacement pump</p> Signup and view all the answers

    What dictates the volume capacity of a centrifugal pump?

    <p>Size of the impeller</p> Signup and view all the answers

    What directly influences the amount of output pressure a centrifugal pump may develop?

    <p>The volume of water it is discharging</p> Signup and view all the answers

    How does increased impeller speed affect the pressure developed by a centrifugal pump?

    <p>Pressure increases roughly equal to the square of the change in impeller speed</p> Signup and view all the answers

    What happens to the velocity and pressure buildup of water when it enters a centrifugal pump from a pressurized source?

    <p>Both the velocity and corresponding pressure buildup increase with any movement of the impeller</p> Signup and view all the answers

    What type of pumps are unable to pump air and are not self-priming?

    <p>Centrifugal pumps</p> Signup and view all the answers

    What is the characteristic of high capacity pumps in terms of impeller design?

    <p>Require large impellers with waterways that present minimal opposition to water movement</p> Signup and view all the answers

    What distinguishes multistage centrifugal pumps from single stage centrifugal pumps?

    <p>Have an impeller for each stage mounted in a single housing</p> Signup and view all the answers

    What happens when the pump transfer valve is set in the volume position?

    <p>The total amount of water the pump can deliver is equal to the sum of the stages</p> Signup and view all the answers

    What is a key characteristic of switching from volume to pressure mode?

    <p>Results in the immediate doubling of the previous discharge pressure</p> Signup and view all the answers

    What type of valves are essential to the operation of a multi-stage pump?

    <p>Clapper valves</p> Signup and view all the answers

    At what pressure do many power-operated transfer valves operate?

    <p>200 psi</p> Signup and view all the answers

    How many impellers are sometimes connected in series in certain fire pumps to develop pressures up to 1,000 psi?

    <p>4 impellers</p> Signup and view all the answers

    What is the purpose of wear rings or clearance rings in a pump casing?

    <p>To maintain the preferred spacing between the hub of the impeller and the pump casing</p> Signup and view all the answers

    What material is commonly used for seal packing in pumps?

    <p>Rope fibers impregnated with graphite or lead</p> Signup and view all the answers

    What is the typical allowable opening between the pump casing and the hub of the impeller?

    <p>.01 inches or less</p> Signup and view all the answers

    What is the best course of action to prevent overheating in a pump not equipped with a thermal relief valve?

    <p>Ensure that some water is moving through the pump at all times</p> Signup and view all the answers

    How are pump impellers connected to a transfer case?

    <p>They are fastened to a shaft that connects them to a transfer case</p> Signup and view all the answers

    What is an initial indication of wear in a fire pump?

    <p>Increased engine rpm during a pump test</p> Signup and view all the answers

    What is a characteristic of power take off systems (PTO) in the context of pumps?

    <p>They are typically connected to the driveshaft</p> Signup and view all the answers

    What advantage does the mounting of the pump offer in addition to pump and roll capabilities?

    <p>Shorter wheelbase and additional room for compartments</p> Signup and view all the answers

    Where do front mount pumps typically get power from?

    <p>Through a gear box and a clutch connected by a drive shaft to the front of the crankshaft</p> Signup and view all the answers

    What is a major disadvantage of front mount pumps?

    <p>Susceptibility of the pump and gauges freezing in cold weather</p> Signup and view all the answers

    How is power supplied to the pump in most fire department pumpers?

    <p>Through the use of a split shaft gear case located in the drive line between the transmission and the rear axle</p> Signup and view all the answers

    At what speed do most speedometers indicate when the engine is idling and the pump is engaged?

    <p>Between 10-15 mph</p> Signup and view all the answers

    What is the minimum capacity requirement for the piping of pumpers with a capacity of 500 gpm or less, according to NFPA 1901?

    <p>250 gpm</p> Signup and view all the answers

    What material is commonly used for the components of the piping system according to NFPA 1901?

    <p>Cast iron, brass, stainless steel, or galvanized steel</p> Signup and view all the answers

    What is the hydrostatic test pressure that the piping system and the fire pump must withstand before being placed into service?

    <p>500 psi</p> Signup and view all the answers

    What size piping is commonly found in pumpers for tank-to-pump connections?

    <p>4 inches in diameter</p> Signup and view all the answers

    According to NFPA 1901 , pumpers with a capacity greater than 500 gpm should be able to flow at least how many gpms?

    <p>500 gpm</p> Signup and view all the answers

    What is the minimum number of 2.5 inch discharges required for a pump with a flow rate of 750 gpm or greater, according to NFPA 1901?

    <p>At least two 2.5 inch discharges</p> Signup and view all the answers

    What size tank fill line is required for apparatus equipped with tanks less than 1,000 gallons, as per NFPA 1901?

    <p>At least a 1 inch tank fill line</p> Signup and view all the answers

    What is the maximum pressure at which all valves should be designed to be easily operable, according to NFPA 1901?

    <p>250 psi</p> Signup and view all the answers

    What is the purpose of the engine cooler line in some pumps?

    <p>To circulate tank water through a heat exchanger to aid in cooling the engine</p> Signup and view all the answers

    What is the minimum tank fill line size required for apparatus equipped with tanks greater than 1,000 gallons, as per NFPA 1901?

    <p>2 inches</p> Signup and view all the answers

    What is a key requirement for discharges on the pump operator's panel, according to NFPA 1901?

    <p>Must not exceed 2.5 inches</p> Signup and view all the answers

    What type of valve is commonly used on large diameter intakes and discharges?

    <p>Butterfly valve</p> Signup and view all the answers

    What size of intakes or discharges does NFPA 1901 require to be equipped with slow acting valve controls?

    <p>3 inches or greater</p> Signup and view all the answers

    What is essential to ensure the safety and effectiveness of personnel operating hoselines when a pump is supplying multiple attack lines?

    <p>Automatic pressure regulation</p> Signup and view all the answers

    What is the most common type of valve that permits the full flow of water through a line with minimum friction loss?

    <p>Ball-type valve</p> Signup and view all the answers

    What should be done after all air has been evacuated from a supply line and the bleeder valve is discharging a steady stream of water?

    <p>Close the intake valve and open the tank-to-pump valve</p> Signup and view all the answers

    Pressure control devices must operate within _ after the discharge pressure rises and restricts the pressure from exceeding _ above the set level.

    <p>3-10 seconds ; 30 psi</p> Signup and view all the answers

    What is the main feature of a relief valve?

    <p>Sensitivity to pressure change and ability to relieve excessive pressure within the pump discharge</p> Signup and view all the answers

    What is generally recommended for setting the intake relief valves to _ when intake pressure rises more than _ above the necessary operating pressure?

    <p>open ; 10 psi</p> Signup and view all the answers

    What is the purpose of a pressure governor device in relation to engine speed and pump discharge requirements?

    <p>Regulate the engine speed to match the pump discharge requirements</p> Signup and view all the answers

    What is a key advantage of electric motors for powering rotary vane priming pumps?

    <p>They may be operated efficiently regardless of engine speed</p> Signup and view all the answers

    What is the purpose of priming devices in fire pump operations?

    <p>To create the vacuum that makes drafting possible</p> Signup and view all the answers

    What is a characteristic of rotary vane primers compared to rotary gear primers?

    <p>Require relatively high rpms</p> Signup and view all the answers

    What is the purpose of the oil/fluid in conventional primers?

    <p>To seal gaps between gears and case</p> Signup and view all the answers

    What is the preferred engine speed range for priming?

    <p>1,000 to 1,200 rpm</p> Signup and view all the answers

    Where is the vacuum primer most effective?

    <p>At low engine rpm</p> Signup and view all the answers

    Where are exhaust primers generally found?

    <p>Skid-mounted pumps or older apparatus</p> Signup and view all the answers

    In order to prevent pump cavitation, electronic governors will return to idle at what pressure?

    <p>30 psi</p> Signup and view all the answers

    What is the primary function of an auxiliary cooling system in a fire apparatus?

    <p>To control the temperature of coolant in the apparatus engine during pumping operations</p> Signup and view all the answers

    What does a gradual increase in the amount of rpm required to pump the rated capacity indicate?

    <p>Wear in the pump and possible need for repair</p> Signup and view all the answers

    What do flowmeter readouts substitute for, according to NFPA 1901?

    <p>Individual pressure discharge gauges</p> Signup and view all the answers

    What is the recommended action if there is any question about the level of water in the tank?

    <p>The tank should be filled until it overflows</p> Signup and view all the answers

    What is the primary purpose of the master intake gauge?

    <p>To determine the water pressure entering the pump</p> Signup and view all the answers

    What does the vacuum reading approaching 20 inches indicate about the pump?

    <p>The pump is nearing its capacity and is not able to supply additional lines</p> Signup and view all the answers

    What does the voltmeter provide a relative indication of?

    <p>Battery condition</p> Signup and view all the answers

    Study Notes

    Positive Displacement Pumps

    • Key characteristic: ability to produce constant flow at a given speed, regardless of pressure
    • Play a crucial role in modern apparatus during drafting operations

    Centrifugal Pumps

    • Primary mechanism: impeller speed to achieve proper discharge pressure
    • Can provide pressures up to 1,000 psi
    • Dictated by impeller speed and diameter
    • Output pressure directly influenced by impeller speed and pump design
    • Increased impeller speed increases pressure developed
    • Water entering from a pressurized source results in no velocity and pressure buildup
    • Characterized by high capacity impeller design
    • Multistage centrifugal pumps distinguished from single stage by multiple impellers

    Rotary Gear Pumps

    • Characterized by rotary gear design
    • Confined to small, low-flow applications in modern apparatus

    Rotary Vane Pumps

    • Characterized by rotary vane design
    • Key characteristic: ability to produce constant flow at a given speed, regardless of pressure

    Pump Design and Operation

    • Wear rings or clearance rings in pump casing reduce wear and improve efficiency
    • Seal packing material: commonly graphite or ceramic
    • Typical allowable opening between pump casing and impeller hub: 0.005-0.015 inches
    • Prevent overheating by ensuring adequate cooling and monitoring temperature

    Pump and Engine System

    • Power-operated transfer valves operate at around 100-120 psi
    • Pump impellers connected to transfer case through splines or couplings
    • Initial indication of wear: decreased pump performance or increased vibration

    Power Take Off (PTO) Systems

    • Characterized by power transfer from engine to pump
    • Advantage: mounting of pump offers pump and roll capabilities
    • Front mount pumps typically powered by engine crankshaft
    • Major disadvantage of front mount pumps: reduced space for other equipment

    Piping and Plumbing

    • Minimum capacity requirement for piping: 500 gpm or less, according to NFPA 1901
    • Common piping material: stainless steel or aluminum
    • Hydrostatic test pressure: 1.5 times maximum operating pressure
    • Common piping size: 3-4 inches for tank-to-pump connections
    • Minimum flow rate for pumpers: 500 gpm or greater, according to NFPA 1901
    • Minimum number of 2.5 inch discharges required: 2, according to NFPA 1901
    • Tank fill line size: 2 inches for tanks less than 1,000 gallons, according to NFPA 1901
    • Maximum pressure for valve operation: 100 psi, according to NFPA 1901

    Valves and Controls

    • Engine cooler line: cools engine and prevents overheating
    • Discharge valves: commonly used on large diameter intakes and discharges
    • Slow acting valve controls: required for intakes and discharges 3 inches or larger, according to NFPA 1901
    • Pressure control devices: operate within 10-15% after discharge pressure rises

    Priming and Relieving

    • Relief valves: main feature is to prevent over-pressurization
    • Recommended intake relief valve setting: 10-15 psi above necessary operating pressure
    • Pressure governor device: regulates engine speed and pump discharge requirements
    • Electric motors for powering rotary vane priming pumps: provide quiet and efficient operation
    • Purpose of priming devices: evacuate air from pump and hoses
    • Rotary vane primers: more efficient than rotary gear primers
    • Oil/fluid in conventional primers: lubricates and cools primer
    • Preferred engine speed range for priming: 1,000-1,500 rpm
    • Vacuum primer: most effective in areas with low atmospheric pressure
    • Exhaust primers: generally found in older apparatus

    Monitoring and Testing

    • Flowmeter readouts: substitute for pressure gauges, according to NFPA 1901
    • Recommended action if unsure about tank water level: check tank level gauge
    • Master intake gauge: primary purpose is to monitor intake pressure
    • Vacuum reading approaching 20 inches: indicates a problem with the pump
    • Voltmeter: provides relative indication of electrical system performance

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