Multistage Centrifugal Fire Pump Transfer Valve Position Quiz and Flashcards

Podcast

Play an AI-generated podcast conversation about this lesson

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?

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

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

Piston pumps Signup and view all the answers

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

Small capacity, booster-type pumps Signup and view all the answers

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

Rotary-type pumps Signup and view all the answers

What is a key characteristic of rotary vane pumps?

They automatically compensate for wear Signup and view all the answers

What type of pump is a centrifugal pump?

Nonpositive displacement pump Signup and view all the answers

What dictates the volume capacity of a centrifugal pump?

Size of the impeller Signup and view all the answers

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

The volume of water it is discharging Signup and view all the answers

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

Pressure increases roughly equal to the square of the change in impeller speed 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?

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

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

Centrifugal pumps Signup and view all the answers

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

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

What distinguishes multistage centrifugal pumps from single stage centrifugal pumps?

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

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

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

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

Results in the immediate doubling of the previous discharge pressure Signup and view all the answers

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

Clapper valves Signup and view all the answers

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

200 psi 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?

4 impellers Signup and view all the answers

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

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

What material is commonly used for seal packing in pumps?

Rope fibers impregnated with graphite or lead Signup and view all the answers

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

.01 inches or less 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?

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

How are pump impellers connected to a transfer case?

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

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

Increased engine rpm during a pump test Signup and view all the answers

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

They are typically connected to the driveshaft Signup and view all the answers

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

Shorter wheelbase and additional room for compartments Signup and view all the answers

Where do front mount pumps typically get power from?

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

What is a major disadvantage of front mount pumps?

Susceptibility of the pump and gauges freezing in cold weather Signup and view all the answers

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

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

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

Between 10-15 mph 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?

250 gpm Signup and view all the answers

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

Cast iron, brass, stainless steel, or galvanized steel 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?

500 psi Signup and view all the answers

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

4 inches in diameter 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?

500 gpm 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?

At least two 2.5 inch discharges 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?

At least a 1 inch tank fill line 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?

250 psi Signup and view all the answers

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

To circulate tank water through a heat exchanger to aid in cooling the engine 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?

2 inches Signup and view all the answers

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

Must not exceed 2.5 inches Signup and view all the answers

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

Butterfly valve Signup and view all the answers

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

3 inches or greater 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?

Automatic pressure regulation 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?

Ball-type valve 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?

Close the intake valve and open the tank-to-pump valve 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.

3-10 seconds ; 30 psi Signup and view all the answers

What is the main feature of a relief valve?

Sensitivity to pressure change and ability to relieve excessive pressure within the pump discharge 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?

open ; 10 psi Signup and view all the answers

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

Regulate the engine speed to match the pump discharge requirements Signup and view all the answers

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

They may be operated efficiently regardless of engine speed Signup and view all the answers

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

To create the vacuum that makes drafting possible Signup and view all the answers

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

Require relatively high rpms Signup and view all the answers

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

To seal gaps between gears and case Signup and view all the answers

What is the preferred engine speed range for priming?

1,000 to 1,200 rpm Signup and view all the answers

Where is the vacuum primer most effective?

At low engine rpm Signup and view all the answers

Where are exhaust primers generally found?

Skid-mounted pumps or older apparatus Signup and view all the answers

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

30 psi Signup and view all the answers

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

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

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

Wear in the pump and possible need for repair Signup and view all the answers

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

Individual pressure discharge gauges Signup and view all the answers

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

The tank should be filled until it overflows Signup and view all the answers

What is the primary purpose of the master intake gauge?

To determine the water pressure entering the pump Signup and view all the answers

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

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

What does the voltmeter provide a relative indication of?

Battery condition 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

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Pumping Apparatus Driver/Operator Chapter 9

Choose a study mode