Chapter 9 Flashcards
Fire Pump Theory
What is a positive displacement pump?
Self priming pump that utilizes a piston or interlocking rotors to move a given amount of fluid through the pump chamber with each stroke of the Piston or rotation of the rotors. Used for hydraulic pumps on aerial devices hydraulic systems and for priming pumps on centrifugal fire pumps
What type of pump does not use positive action to force water from the pump rather it depends on the velocity of the water produced by centrifugal force to provide the pressure needed to achieve proper discharge pressure?
Centrifugal pump
What is a piston pump?
Positive displacement pump using one or more reciprocating Pistons to force water from the pump Chambers
Piston pumps rotary pumps rotary gear pumps rotary vein pumps are all examples of?
Positive displacement pumps
Type of positive displacement pump commonly used in hydraulic systems. A rotor with attached veins 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?
Rotary vane pump
A pump with one or more impellers that rotate and utilize centrifugal force to move the water. Most modern fire pumps are of this type?
Centrifugal pump
What type of pump is classified as a non positive displacement pump?
Centrifugal pump
A spiral divergent chamber of a centrifugal pump in which the velocity energy given to water by the impeller blades is converted into pressure is called a?
Volute
An intake orifice at the center of a centrifugal pump impeller?
Impeller eye
Veined, circulating member of the centrifugal pump that transmits motion to the water is called?
Impeller
What are three main factors that influence a centrifugal fire pumps discharge pressure?
Amount of water being discharged
Speed at which the impeller is turning
Pressure of water when it enters the pump from a pressurized source hydrant relay etc
Spiral, divergent chamber of a centrifugal pump in which the velocity energy given to water by the impeller blades is converted into pressure is called?
Volute
Vaned, circulating member of the centrifugal pump that transmits motion to the water is called?
Impeller
Intake orifice at the center of a centrifugal pump impeller is called?
Impeller eye
What are the two basic types of centrifugal pumps that are used by the fire service?
Single stage and multistage
Pumps used in the fire service constructed with a single impeller are referred to as?
Single stage centrifugal pump
A pump that has an impeller for each stage mounted in a single housing is called a?
Multistage centrifugal pump
Process of switching between pressure and volume is sometimes referred to as?
Changeover
Hinged valve that permits the flow of water in one direction only?
Clapper valve
Replaceable rings that are attached to the impeller and or the pump casing to allow a small running clearance between the impeller and pump casing without causing wear of the actual impeller or pump casing material?
Wear rings
What are some most common applications for auxiliary engine driven pumps?
Arfff vehicles
wildland fire apparatus
Mobile water supply apparatus trailer mounted fire pumps portable fire pumps
A mechanism that allows a vehicle engine to power equipment such as a pump, winch, or portable tool it is typically attached to the transmission?
Power take off system (PTO)
The ability of an apparatus to pump water while the vehicle is in motion is called?
Pump and roll
Fire pump mounted in front of the radiator of a vehicle and powered off the crankshaft is called?
Front mount pump
One major disadvantage of the front mount pump is?
The susceptibility of the pump and gauges freezing and cold weather due to their exposed position
The driver operator May check to see that the transmission is in the correct gear by observing the speedometer reading after the pump is engaged with the engine idling in the pump and cage most speedometers will indicate between ______ and _______ mph?
10 to 15
Automatic valve that permits liquid to flow in only one direction?
Check valve
The most common applications for auxiliary engine driven pumps are?
ARFF, brush truck ,mobile water supply,trailer mounted fire pumps
How many gallons or less is the pumping capacity for an auxiliary engine driven pump?
500 gallons or less
On an automatic pressure control device it must operate within three to ten seconds after the discharge pressure rises and restricts the pressure from exceeding _____ psi above the set level?
30 psi
What are the two basic concepts for pressure relief valves?
Those that relieve excess pressure on the discharge side of the pump
Those that relieve excess pressure on the intake side of the pump
A pressure control device that controls engine speed, eliminating hazardous conditions that result from excessive pressures is called a what?
Pressure governor
A condition in which vacuum pockets form due to localized regions of low pressure at the vanes in the impeller of a centrifugal pump, causing vibrations, loss of efficiency, and possibly damage to the impeller is called?
Cavitation
The electronic governor also features cavitation protection by returning the engine to idle when intake pressure drops below ____________ PSI
30
Any device, usually a positive displacement pump, used to exhaust the air from inside a centrifugal pump and the attached hard suction this creates a partial vacuum allowing atmospheric pressure to force water from the static source through the suction hose into the centrifugal pump is called a?
Priming device
Physical law stating that when a fluid such as water or air is forced under pressure through a restricted orifice there is an increase in the velocity of the fluid passing through the orifice and a corresponding decrease in the pressure exerted against the sides of the constriction because the surrounding fluid is under greater atmospheric pressure it is forced into the area of lower pressure called?
Venturi effect
A device used for measuring existing voltage in an electrical system is called?
Voltmeter
They gauge that indicates both the amount of electrical current being drawn from and provided to the vehicle’s battery is called?
Ammeter
What are two types of auxiliary cooling devices?
Marine or immersion type
