Module 5 - Fire pump theory and construction Flashcards
METHODS OF ENGINE-TO PUMP POWER TRANSFER
Power Take-Off Drives (PTO)
Midship Transfer Drive
Power Take-Off Drives (PTO)
Powered by an idle gear in the transmission and is used primarily on the CFD to operate Aerial PTOs or generator PTOs
Transmissions are placed in the neutral position when operating these PTOs
Midship Transfer Drive
Used on most CFD apparatus to operate the pumps
This system has the pump connected to the split-shift transfer case located on the driveline between the transmission and rear axle
This system is operated with the transmission in drive
Positive Displacement pumps
- Hydraulic Law
When pressure is applied to a confined liquid, the same outward pressure is transmitted within the liquid and equally in all directions
There are two basic types of positive displacement pumps
Piston
Rotary
Piston
Contain a piston that moves back and forth inside a cylinder
The pressure developed by this action causes intake and discharge valves to operate automatically and provides for the movement of water through the pump
Rotary
Rotary gear - Pump consist of two gears that rotate in a tightly meshed pattern inside a watertight case
Rotary vane – pumps are constructed with moveable elements that automatically compensate for wear and maintain a tighter fit with closer clearances as the pump is used
Two great advantages that the centrifugal pump has over the positive displacement pump is that:
They can take advantage of incoming pressure
Little to no harm results from shutting of all discharges for a short time
Three main factors greatly influence a centrifugal fire pumps discharge pressure
- The amount of water being discharged
- The speed at which the impeller is turning
- The pressure that the water has when it enters the pump from a pressurized source
The amount of water being discharged
The greater the volume of water being flowed, the lower the discharge pressure will be
The speed at which the impeller is turning
The greater the speed of the pump, the greater the pressure will be developed
This increased is approx.. equal to the square of the change in impeller speed
The pressure that the water has when it enters the pump from a pressurized source
The incoming pressure changes will be reflected in the discharge pressure
PUMP ASSEMBLY
- Waterous CMU20 – 2 stage pump, 2000 GPM or 600psi output
- 200 CFM encapsulated rotary screw compressor
- Eclipse compressed air foam system
- foam manifold
- compressor oil filter
- air outlet manifold
- Y- Strainer
- compressor
- compressor oil heat exchanger
- clutch
- water inlet relief valve
- pump transmission 10. water inlet butterfly valve
Three parts to the Waterous Pump:
Impeller shaft assembly
o 2 piece stainless steel shaft
o Bronze impeller
Pump body assembly
Transmission assembly
Impeller
Transmits energy in the form of velocity to the water
Casing
Collects the water and confines it to convert the velocity to pressure
It then directs the water to the discharge of the pump
centrifugal pump
Bronze Impeller
- front shroud 4. Eye
- exit way 5. Vanes
- hub 6. Bore
The impeller is mounted off-center in the casing
This creates a water passage that gradually increases in cross-sectional area as it nears the discharge of the pump. This section of the pump is known as the volute
Impeller
- Vanes
- Stripping edge
- wear rings
Wear Rings
Bronze wear rings are used to restrict the amount of water allowed through
The wear rings are trapped in the pump body
The hub of the impeller fits inside the wear ring
Overheat Protection Manager (OPM)
Acts as a safety device by releasing hot water to the ground from the discharge side of the pump
The valve itself is capable of resetting after the temperature drops below 104 degrees Fahrenheit at pressures greater than the truck can produce
Will alarm and the red light will illuminate once the water temperature in the pump body reaches a predetermined temperature of 180 degrees Fahrenheit
The system will then automatically begin dump water out of the pump body at 140 degrees Fahrenheit
Electronic Transfer Valve Actuator
Should remain in volume position
Electronic Transfer Valve Actuator – The following criteria dictates when the valve should be moved
When flowing over 2/3 the capacity of the pump (over 4667 L/Min) have the valve in volume position
When flowing over 1400 kPa have the valve in the pressure position
oT
e valve may be operated at pressures up to 1700kPa without damage to the pump
do not switch from volume to pressure with handlines flowing
There are two pumping positions
Volume (parallel)
Pressure (series)
Volume (parallel) position
Each of the impeller takes water from a source and delivers it to the discharge
Each of the impellers is capable of delivering its rated pressure while flowing 50% of the rated capacity
Pressure (series) Position
All the water from the intake manifold is directed into the eye of the first impeller
The first stage increases the pressure and discharges 50-70% of the volume capacity through the transfer valve and into the eye of the second impeller
The second impeller increases the pressure and delivers the water at a higher pressure into the pump discharge port
Pressure mode should be used when operating at a pressure higher than 1400 kPa
Transfer valves are capable of operating at 1700kPa however best practice is to set the PSG to idle prior to operating the transfer valve
Clapper Valves
Are essential in a two-stage pump
If they should stick open or closed or get debris caught in them, the pump will not operate properly in the pressure (series) position
Cavitation
Water is being discharged from the pump faster then it is coming in
Occurs when air cavities are created in the pump or bubbles pass through the pump
Maintain 150kPa on the compound gauge when operating from a pressure fed supply will prevent cavitation
Overheating
Can be caused by the pump being run for extended periods of time with little or no water flowing
This can be rectified by either opening a dump line, circulating the water through the tank, opening the pump cooler, utilizing the OPM or if there is no water required the pump can be shut down
RATED PUMP CAPACITIES
ULC Plate
Displays pump performance
As discharge pressure is increased the volume is greatly reduced
1000 kPa is the optimum pump discharge pressure for maximum volume
PUMP TRANSFER CASE - Pneumatic shifter
Moves back and forth across the 3 gears always in contact with 2 of the 3 gears
Connecting the drive(green) to either the rear driveshaft to the wheels (yellow) or to the pump gear (blue)
INTAKE RELIEF VALVE
CFD engines are equipped with two inlet relief valves:
o Located on the TFT intake ball valve, set to activate at 1260kPa or less
o Located on the intake side of the main pump casing and set to activate at approx.. 1100kPa
PRIMING SYSTEMS
Before any centrifugal pump can be operated, it must be primed
Priming is the process of replacing air in the intake lines and portions of the pump with water
If the pump is to be operated from a draft, priming must be done by means of a positive displacement pump
Primers fall into two categories:
- Positive displacement primers
o Used on CFD apparatus - Exhaust primers
Priming Valve
A rubber diaphragm forms a seal that allows the valve to open and close while isolating the interior of the priming valve from atmospheric pressure
The priming valve is attached directly to the highest point on the pump body
Opens automatically during the pump priming
When the valve is open, it allows air to flow from the various pump passages to the priming pump, once the pump is primed, the priming valve closes automatically when the primer is deactivated
if the priming pump does not prime the main pump and discharge a steady stream of water within
45secs, stop the pump and determine the cause of the problem
PUMP CONTROL PANELS
Drivers side - pump
front compartment - pump
officers side - pump
Electronic Governors - operate in one of two modes
Pressure
RPM
Pressure
Maintains a constant pump discharge pressure, varies the engine speed to maintain the desired pressure
RPM
Maintains a constant engine RPM (mostly used in drafting or relaying)
Ball valves
Are used in pumper discharges, the fire piping systems and gated wyes
Are open when the handle is in line with the hose and closed when then handle is at a right angle to the hose
Gated valves
Used to control the flow from the hydrant
Have a baffle that is moved by a handle and screw arrangement
Have been designed to be fully open or closed
Butterfly valve
Is a flat baffle operated by a quarter-turn handle
Quick opening valves and are similar in operation to a ball valve, but does not have any pockets in which fluids may become trapped when the valve is closed
Clapper valve
Used in Siamese appliances, sprinkler and standpipe systems
To allow only one intake hose to be connected and charged before the additional of more hoses
Waterous Advantus foam system
Engines up to 2017-2018 advantus 3 and all Smeal quints advantus 6
Major difference between advantus and Aquis is
the Aquis system does not use conductivity probes in the foam manifold, it only uses the flowmeter to calculate how much concentrate to inject into the foam manifold foam
Red is Advantus, Blue is Aquis
Applications and advantages of flow meters:
Diagnosing water flow problems
Simplify the use of in-line foam educator
Require little maintenance
WATEROUS POWER FOAM FILL SYSTEM
This system allows pump operators to fill the foam concentrate holding tank, while still standing on the ground
Allowing the pump operator to fill the foam tank while flowing foam at a fire scene
FLUSHING SYSTEM
After every use, the foam fill system must be flushed
With he wand in clean water and the tank fill/flushing valve in the flush position, depress and hold the manual fill button
Drain valves
These valves may be used to relieve pressure in the line and make it easier to disconnect the hose, or may be used to belled off air from within the hose line
They should be used in cold weather operations to remove any water out of the pipes to prevent freeze up
Gauge Drains
Remove water from the gauges to help prevent freeze up
Auxiliary coolers
Marine and immersion
The primary function is to control the temperature of the coolant in the apparatus engine during pumping operations
Auxiliary coolers - Marine
inserted in one of the hoses used in the engine colling system in such a way that the engine coolant must travel through it as it circulates through the system
Auxiliary coolers - immersion
mounted similarly to the marine type, with the radiator coolant passing through a coil or some tubing mounted inside the cooler so that it is immersed in the coolant
Strainer screens
Designed to stop large foreign bodied objects from entering the pump
Another function is to straighten this stream prior to it entering the pump
Are composed of zinc alloy, and are designed as a sacrificial anode; this helps reduce corrosion in the pump
