Pumping Flashcards
What is a pump?
A pump is a machine driven by some external power, for transmitting energy to fluids.
What type of pump does ACTFR use and how does it work?
Centrifugal Pumps: use centrifugal force which is the tendency of a body to move outwards from a rotating centre.
What are the two main parts of a centrifugal pump?
The Impeller and the casing.
What does the impeller do?
When it rotates, water is discharged from the periphery by way of centrifugal force. This also creates a vacuum at the centre and water is sucked into the inlet which in turn feeds the impeller.
Name three parts of an impeller
1 - Water inlet
2 - Vanes
3 - Periphery
From what energy does the impeller convert into another form of energy?
The impeller converts kinetic energy to pressure energy.
What happens if the pump operates without discharge, what can happen?
Heat energy can build up which can then damage the pump.
What are the five components of a casing?
1 - water inlet
2 - impeller
3 - guide vanes
4 - volute
5 - delivery outlet
What do the guide vanes do?
Help guide water along the correct path in the casing. Also help reduce turbulence. Allow for kinetic energy to convert to pressure energy.
What does the casing do?
Designed to reduce turbulence and friction by creating a smooth a flow as possible.
How is the kinetic energy converted to pressure energy?
When the water enters the casing via the impeller, the velocity is reduced converting into pressure energy.
What ratio does the high pressure pump work at?
2:1 ratio
What does the high pressure pump do and what kPA should it be operated at?
Supplies water to the high pressure hose reel only and requires atleast 2000kPa for atomisation of water. The high pressure pump spins at a higher rpm than main pump and also heats up quicker.
What sort of shaft seal does ACTFR employ and what does it do?
All pumps employ a mechanical seal, stop water leaking into gear casings.
What can damage a mechanical seal?
Heat Energy
What factors determine pump capacity?
Intake diameter, impeller eye diameter, outside diameter of impeller, width of impeller, shape and number of vanes on impeller, design of volute chamber.
What are the rated capacity of Darley pumps in ACTFR?
Old Darley LDMH 1000: 3,800 L/min @1000kpa
New LDMH 1500: 5700 L/min @1000kpa
How can you reduce or eliminate air in the pump?
Use the primer or open a valve.
What is the relationship between pressure and head?
Head effects pressure by changes in height.
P = H x 10
What is cavitation?
Water boils are lower temps in a vacuum. If pressure on suction side of pump falls below vapour pressure of water, bubbles form. These bubbles are carried into the inlet, implode and can cause damage by breaking away small parts of metal.
What are some causes of cavitation?
The lift is too high for the volume of water and pressure being discharged.
The suction hose diameter is too small for the volume of water being discharged.
Restriction of suction line
Temperature of water being pumped is too high.
Hydrant supply being overrun.
What are some indications of cavitation?
Sounds like small stones passing through pump.
Engine revolution’s will increase.
Compound gauge will show negative pressure and collector hose will go soft.
Decrease in delivery of flow.
When draughting, gauge will drop below -75kPa
How does and what can happen when there is air in the pump?
Through leaky suction joint, or run out of foam concentrate. Air bubble will compress then expand with explosive force when it leaves the nozzle. Does not damage pump cause it does not implode.
How do you find Litres per minute?
kPA divide 10, then take away 50
E.g 2000kpa divide by 10 = 200,
200 minus 50 = 150L/per minute
How does a centrifugal pump work?
Operates by using centrifugal force, that is, the tendency of a revolving body to fly outward from the centre of rotation.
How does a centrifugal pump work?
Operates by using centrifugal force, that is, the tendency of a revolving body to fly outward from the centre of rotation.
What raises the water when draughting?
Atmospheric pressure alone raises the water.
What factors affect lift?
Density of water.
Loss due to change in direction of water
Overcoming frictional loss
Any restriction on suction hose
Mechanical condition of pump
What is the maximum practical suction lift in ACT
7.5meters
Why does the pump have a primer?
Centrifugal pumps are incapable of pumping gas, therefore primer will push air out and fill pump with water.
What type of primer does ACTFR use and how does it work?
Rotary sliding vane primers: rotor is set off centre in casing. Rotor has blades that slide outward due to centrifugal force. When blades fly out they make contact with casing and as the rotor spins the blades create a vacuum which in turn sucks air in and then expels it.
When siting an appliance, what considerations must be made?
The three p’s principals
Positioning - effective placement
Potholes - terrain
Power - overheads
When relay pumping, what considerations are made in terms of distance?
The distance between pumps, biggest pump at base and no more than six lengths of 64mm hose
What are the three types of relay pumping?
Tank relay - filling a appliance with a tanker
Open circuit relay - pump to portable dam
Closed circuit relay - pump to pump
When working from an open water supply, what are some common faults?
Strainer not fully immersed in water
Suction hose has sharp curve
Lift is more than 7.5 meters
Suction and coupling joints not tight enough
Pump not correctly engaged
When draughting, what does -75kPa indicate?
You have overrun supply.
What are some reasons for loss of supply pressure?
Branch being opened
Kinks in collection hose
Stand pipe being turned off
Weight on collector hose
Burst hose
Failure of reticulated supply
Why must tank supply remain full?
If failure of external supply occurs, tank supply can be used.
What must be done before engaging the monitor?
Engine to idle.
What can the compound gauge tell us?
That supply is being overrun.
What extra cooling does the p series varley have?
Pump to tank switch which circulates water to tank and be used at anytime.
At what rate does the supplementary cooling occur on the P series varley?
60L/m
Name six supplementry cooling techniques.
Open high pressure branch onto ground
Open high pressure branch into tank filler
Open branches regularly
Connect delivery to tank filler outlet with filler length
Disengage high pressure pump when not in use
Throttle back when high pressure is not required.
What can you do if pressure relief valve continues to operate after being shut off?
Close relief shut off valve.
How much pressure will the pressure relief valve bleed off?
200kPa
What does the pressure relief valve do?
Regulates delivery pressure to mitigate pressure spikes. Does not affect high pressure hoses.
What are the two ways of reading the compound gauge?
When using a closed supply, gauge will measure pressure of water entering pump.
When draughting it will measure lift in the negative.
What does the high pressure gauge show?
The amount of delivery pressure from the high pressure pump.
What does the main pressure gauge show?
The amount of delivery pressure from the main pump.
How many flow meters are there and how do they measure flow?
Four, one for each delivery. Measures in litres per minutes
Name all the water delivery valves.
4 x 64mm delivery valves
2 x 25mm high pressure delivery valves
1 x monitor
What does the emergency stop do and how do you reset it?
Shuts down the engine
Reset by: idle, ignition off, restart engine, select drive, pumps already engaged. Pumping recommences.
What are the three pump panel configurations in ACTFR?
Series IV, Series P Varley, Series P Fraser
What two things does the compound gauge measure to get a reading?
Pressure and vacuum.
How would you be able to tell that the pressure relief valve was working if indicator lamp wasn’t working?
Slight drop in pump rpm and water flow through the valve.
What does a primer do?
Obtain suction lift when draughting and refill the pump casing with water.
Why is it important to tie off coupling joints on suction hose when draughting?
To take weight off coupling joints
When using closed supply (hydrant), what would a gradual increase in delivery pressure show?
Branches being shut off
Delivery hose dragged into kink
In relay, pump closest to fire shutting down
When using a closed supply (hydrant), what would a sudden increase in pressure show?
Weight placed on delivery hose
All branches shut off
In closed water usage, what would a gradual decrease in pressure show?
Branch being opened
Kink taken out of delivery hose
Stand pipe being partially turned off
Weight on collector hose being removed
In a closed supply, what would a sudden decrease in pressure be caused by?
A burst collection hose
Failure of reticulated water supply
What may a gradual decrease in vacuum and decrease in pressure be caused by?
A vortex being created at strainer letting air in
Suction hose joints loose
Deterioration of washers
What are two reasons the primer may have failed after being engaged for 45 seconds?
Lift is more than 7.5 meters
Couplings on suction hose letting air in
