The modern fire department is equipped with a ($$$$$) as its main pump.
Centrifugal pump
The ($$$$$$) does not use positive action to force water through the pump, it depends of the velocity of the water produced by the centrifugal force to provide the necessary pump discharge pressure for effective operation.
Centrifugal pump
The forward stroke causes waster to be discharged, and the return stroke causes the pump to fill with water again. This is known as a ($$$$$$). Adding two additional valves can produce a more constant stream. This is known as a ($$$$$$) because it both receives and discharges water on each stroke of the piston.
Single acting piston pump
Double a ting piston pump.
Although piston pumps are no longer used as high capacity pumps, some are still in service for high pressure stream fire fighting. These multi cylinder , PTO driven pumps provide pressures up to ($$$$$)
1000 psi
($$$$$) pumps are the simplest of all fire apparatus pumps from a stand point of design.
Rotary type
The ($$$$$) consists of two gears that rotate in a tightly meshed pattern inside a water tight case.
Rotary gear pump.
The ($$$$$) is constructed with movable elements that automatically compensate for wear and maintain a tighter fit with close cleanser cues as the pump is used.
Rotary vane pumps
In this type of pump the rotor is mounted off center inside the housing. The distance between the rotor and the housing is much greater. At the intake than it is at the discharge.
Rotary vane pumps
The ($$$$$) is classified as a non positive displacement pump because it does not pump a definite amount of water with each revolution.
Centrifugal pump
Fundamentally the centrifugal pump consists of two parts: an ($$$$) and a ($$$$$)
Impeller
Casing
The ($$$$) transmits energy in the form of velocity.
Impeller
He ($$$$) collects the water and confines it in order to convert the velocity into pressure.
Casing
The impeller rotate very rapidly, generally from ($$$$$$).
2000 to 4000 rpm
The impeller is mounted off center in the casing. This placement creates a water passage that gradually increases in cross sectional area as it nears the discharge outlet of the pump. This section of the pump is known as the ($$$$$)
Volute
The greater the speed of the impeller the greater the ($$$$) developed.
Pressure
Ther are two basic types or centrifugal pumps used by the fire service
Single stage and
Two stage
Front mount pumps, power take offs separate engine driven, and mid ship transfer pumps use a single impeller and a simple casing to pro vide capacities up to ($$$$$).
2000 gpm
To minimize the lateral thrust of large quantities of water entering the eye of the impeller a ($$$$$$$) was designed.
Double suction impeller
The ($$$$$$) takes in water from both sides; the reaction being equal and positive cancels the lateral thrust.
Double suction impeller
The ($$$$) has an impeller for each stage mounted within a single housing.
Multi stage centrifugal pump
If a two stage pump is rated at 1000 gpm at 150 psi each of the impellers supplies ($$$$$) to the pump discharge manifold. There the two stream combine, so the total is 1000 gpm at a net pump pressure of 150 psi
500 gpm
Changing the pump discharge pressure to the ($$$$), position greatly increases the maximum pressure attainable. However increasing pressure results in a corresponding decrease in volume.
Series or pressure
When the transfer valve is in the ($$$$)position, all the water from the intake manifold is directed into the eye of the first impeller.
Pressure
The process between switching from pressure to volume is sometimes referred to as ($$$$)
Change over
The maximum net pump pressure at which the transfer valve should be operated varies. In most cases this recommended maximum pressure will not exceed ($$$$$).
50 psi
Many power operated transfer valves operate at pressures as high as ($$$$). These pressures can represent extreme danger to personnel and equipment,
200 psi
The pressure in the volute is much higher than that at the intake side of the pump at the eye of the impeller, so a very close tolerance must be maintained between the pump casing and the hub of the impeller. The opening is usually limited to ($$$) or less.
0.01 inch
The most common type of packing is material made of rope fibers impregnated with ($$$$) or ($$$$).
Graphite
Lead
($$$$) are those pumps that are powered by a gasoline or Diesel engine independent of an engine used to drive the vehicle.
Auxiliary engine driven pumps.
With engine idling and the pump engaged most speedometers read ($$$$$)
10 to 15 mph
These units are driven by a shaft from the front of the vehicles engine. The shaft turns a hydraulic pump that drives a midship mounted or rear mounted centrifugal water pump. Can be used for stationary or pump and roll operations.
Hydrostatic pumps
The piping system (as well as the pump itself) must be able to withstand a hydrostatic test of ($$$$) before being placed into service.
500 psi
NFPA 1901 states that piping should be sized so that pumpers with a capacity of 500 gpm or less should be capable of flowing ($$$$) from their booster tank. Pumpers with capacities greater than 500 gpm s should be able to flow at least ($$$$)
250 gpm
500 gpm
Discharges to which 1 1/2, 1 3/4, 2 inch hand lines are attached must be secured by at least ($$$$) piping
2 inch
All valve should be designed so that they are easily operable at pressures of up to ($$$$$).
250 psi
NFPA 1901 requires that apparatus with a water tank that is less than 1000 gallons in size to have a tank fill line that is at least ($$$$) in diameter. Apparatus with tanks that are 1000 or larger must have at least a ($$$$) tank fill line.
1 inch
2 inch
The most common type of valve is the ($$$$$) valve that permits full flow through the lines with a minimum friction loss.
Ball type valve
Gate valve are most commonly operated by ($$$$$$$).
Hand wheel
NFPA requires all valves on I intakes or discharges that are 3 inches or greater be equipped with ($$$$$$$)
Slow acting valve controls
NFPA 1901 requires that some type of pressure control device to be part of any fire apparatus pumping system. The device must operate within ($$$$$) after discharge pressures rise and must not allow the pressure to exceed ($$$$) above set level.
3 to 10 seconds
30 psi
There are many types of relif valves available. One of the most common types uses a ($$$$$)
Spring controlled pilot valve
The main feature of a ($$$$$) is that it regulates the power output of the engine to match pump discharge requirements
Pressure governor
Primers fall in to three categories
Positive displacement
Exhaust
Vacuum
The ($$$$$$) requires a relatively high rpm as compared to a rotary gear primer and can be driving by either mechanical means from the pump transfer gear case or by an electric motor.
Rotary vane primer
The ($$$$$) operates on the same principle as foam educators. Exhaust gases from the vehicles engine are prevented form escaping to the atmosphere by the exhaust deflector. The gasses are diverted to a chamber where the velocity f the gasses passing through a Venturi creates a vacuum.
Exhaust primer.
The ($$$$) (sometimes referred to as the($$$$$)) must be connected to the intake side of the pump. This gauge must be capable of measuring either positive pressure or a vacuum.
Master intake gauge
Vacuum or compound gauge
The MASTER INTAKE GAUGE. Is usually calibrated from ($$$$) positive pressure and from ($$$$) of mercury on the intake side.
0 to 600 psi
0 to 30 inches
As the vacuum reading approaches ($$$$), the pump is near its capacity and is not able to supply any additional lines.
20 inches
A MASTER PUMP DISCHARGE GAUGE is also required on a pumper. It must be calibrated to measure ($$$$) unless the pumper is equipped to supply high pressure fog streams; in which case the gauge may be calibrated up to 1000 psi
600 psi
The ($$$$$) reads the engine speed in revolutions per minute (rpm)
Tachometer
The ($$$$$) reads the engine speed in revolutions per minute (rpm)
Tachometer
The ($$$$$$) shows the temp attire of the coolant in the engine that powers the fire pump.
Pumping engine coolant temperature indicator
The ($$$$$$$) shows that an adequate supply of oil is being delivered to critical areas of the engine that is powering the fire pump.
Pumping engine oil pressure indicator
The ($$$$$) provides a relative indication of battery condition and alternator output by measuring the drop in voltage as some of the more demanding electrical accessories, such as the primer are used.
Voltmeter
The most common common throttle used on the pump operators panel is the type of knob that turns. The throttle knob also called a ($$$$$) is turned one way or another until the desired rpm is achieved.
Vernier
The ($$$$$) is inserted into one of the hoses used in the engine cooling system so that the engine coolant must travel through it as it circulates through the system. The cooler its self contains a number of small tubes similar to those in a steam boiler.
Marine type
The ($$$$$) is inserted into one of the hoses used in the engine cooling system so that the engine coolant must travel through it as it circulates through the system
Marine type
($$$$$$) the water being supplied by the pump passes through a coil
Immersion type cooler