Pumping Flashcards
5 Laws of friction loss
Friction loss increases directly with the length of the hose
Friction loss increases directly with the decrease in diameter
Friction loss increases directly as the square of the flow rate. Double flow equals 4 times pressure loss
Friction loss increases with the roughness of the interior of the hose.
Friction loss, for all practical purposes, is independent of pressure.
Friction loss DRISL
D Diameter of hose
R Roughness of hose
I Independent of pressure
S Square of the flow rate
L Length of hose
1m head equals
10 KpA
Loss of friction in each hose @ 500l/m?
38mm 220kpa
50mm 75kpa
65mm 25kpa
90mm 5kpa
The water supply for firefighting may come from
A static/open source such as a dam, creek or swimming pool.
A pressurised source such as a hydrant, the pump of another firefighting appliance or
an elevated tank.
What is a pump
A pump is a mechanical device that pushes or moves fluid or air from one place to another
2 main parts of pump
Volute - part of the pump casing itself and is shaped like the shell of a snail
Impeller - circular disc (the back shroud) with curved vane
Advantages of Centrufugal pump
Steady flow
◼ Operates at variable pressures
◼ Simple construction and operation
◼ Easily maintained and less likely to be damaged
◼ Pumps dirty or gritty water with minimal damage to pump
◼ Small and compact
◼ Flow can be interrupted without stopping engine
◼ Can be connected to an internal combustion engine by direct drive
Disadvantages of Centrifugal
A centrifugal pump cannot displace air and needs to be primed if no water is present
in the pump casing
An additional pump is required to do this, one that is able to displace the air and
introduce water into the main pump casing
Requires different design features, rotation speeds and engine power combinations
compatible with pumping water efficiently
Types of centrifugal pumps
SIngle stage
Multi stage - Series
- Parralel
Duty point - Flow from pumps
Heavy Pump
4000l/min @1000kpa 3m lift
MK5
3800l/min @1000kpa 3m lift
Compound gauge - green
The compound gauge shows atmospheric pressure.
Measures pressure on the inlet side of the pump
Can be positive when pressurised water is entering the pump (such as from a
reticulated supply)
Can be negative (red) when air is being displaced by the primer (such as when using tank
supply or drafting from a static supply) or water supply is being overrun (attempting to
deliver more water than is available from the pressurised supply)
Low pressure
Main pump
Orange MK5
Blue HEAVY
Shows the water pressure in the main pump or low pressure pump casing in kPa.
Gauge is labelled ‘low pressure’ as it is the outlet of the first impeller, which is a lower pressure than the outlet of the second impeller which is connected in series
Maximum operating pressure of the main pump is 1400kpa
High pressure - RED
Always red and linked to the hose reels
Maximum is 4000kpa
Mk5 2000kpa
Heavy 3000kpa
Portable pumps
Portable pumps are independent pumping units that can be carried by one or several firefighters. They are usually centrifugal pumps powered by a small diesel or two or four stroke petrol engine.
Mid mounted appliance pump
Located behind
crew cabin and fixed to vehicle chassis.
The pump is driven by the vehicle’s engine through a power take-off which draws engine power through a
supplementary transmission and shaft to the pump.
PTO
The PTO is attached directly to the transmission. When activated, it directs power away from the vehicle driveline to the pump shaft
Depending on the location of the PTO in relation to the transmission, some
appliances will need to be placed in Drive (D) after PTO engagement to start
the pump, whilst others can remain in Neutral (N) when the PTO is engaged. Since the PTO directs engine power to
the pump and away from the wheels, the appliance cannot be moved once the PTO is selected
Safety margin on compound
100kpa
Siting appliance
Ensure you are visible to other road users. Do not park in blind spots (over crest of a
hill or immediately around blind corners).
◼ Position the appliance off the roadway on hard, even ground (if possible).
◼ Apply the parking brakes and, if necessary, place wheel chocks.
◼ Position the appliance up-wind and up-hill from the fire or incident.
◼ Be mindful of the possibility of fire escalation, explosion and building collapse.
◼ Park clear of power lines or trees that may be affected by the fire.
◼ If possible, park the appliance so the incident is visible from the pump panel.
◼ Keep access clear for the arrival and departure of other emergency service vehicles.
◼ Give yourself adequate space for all fireground operations
◼ Position the pump to make best use of the water source
