Pumping Operations Flashcards
What is a pump
A pump is a machine, driven by some external power, for transmitting energy to fluid. Could be hand pump or suitable driven engine.
What is a centrifugal pump
A centrifugal pump operates by using centrifugal force, that is, the tendency of a revolving body to fly outward from the centre of rotation.
The construction of the centrifugal pump consists of two main parts:
Impeller
Casing
The centrifugal pump converts kinetic energy into pressure energy.
What is the impeller
The impeller is rotated by means of an external power source.
Rotation induces a flow of water through the impeller passages and causes a partial vacuum at its inlet, which in turn induces more water into the suction inlet.
Water from the suction inlet (eye) is picked up by the impeller vanes and is energised as the impeller spins then discharged at high velocity out the periphery. As the water enters the casing most of this kinetic energy is converted into pressure energy.
What is the casing
The casing is designed to reduce turbulence and friction by creating as smooth a flow as possible.
The kinetic energy of the water when it leaves the impeller is converted into pressure energy as the water enters the casing. This is achieved by reducing the velocity of the water.
What is the volute
Shaped like a snail shell.
Water is thrown from the impeller and travels through a passage that steadily increases in cross sectional area until the delivery outlet.
This reduces the velocity of the water.
What are impeller vanes
Water enters through the inlet and travels towards the periphery through the vanes by centrifugal force. As it travels through the vanes it increases speed and discharges as high velocity.
How does a centrifugal pump work
Water is drawn from the suction inlet.
Water flows through the impeller vanes driven by external source making a partial vacuum and increasing velocity and kinetic energy.
Water enters the casing and travels through the volute reducing velocity and transferring kinetic energy into pressure energy.
High pressure pump
Is separate to main pump.
Must be activated in cabin first.
Should operate at 2000 kPa to produce significant atomisation.
Designed to operate to 4200 kPa where the kunkel valve will relieve pressure above.
HP casing only hold 1L of water and must be cooled if on but not in use.
How is the pump shaft sealed
By mechanical seal
Scania Urban Pumpers Capacity
Darley LMDH 1000 main pumps rated capacity of 3800 L/min at a pressure of 1000 kPa.
Darley LMDH 1500 main pumps rated capacity of 5700 L/min at a pressure of 1000 kPa.
Darley LMDH 1000 high pressure pumps rated capacity of 380 L/min at a pressure of 4100 kPa.
Fire ground calculations
Pressure and head calculations
Pressure is the force at which water is delivered.
Head is the vertical depth of a water column.
P = H x 10
In kPa
What is cavitation
When boiling occurs in the suction side of the pump.
This occurs when the pressure on the suction side of the pump falls below the vapour pressure of water.
Can cause major damage to impeller.
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.
There may be a restriction or partial collapse of the suction line.
Hydrant supply being over-run.
Indicators of cavitation
The pump will make noise like there were many small stones passing through. (this is imploding vapour bubbles)
The engine evolutions will increase. (the engine is not pushing as much water so the engine does not have to work as hard)
When operating from a hydrant supply, the compound gauge will show a negative pressure and the collector hose will go soft. (over running supply)
When droughting, the compound gauge will show the maximum lift (will drop below -75kPa)
Decrease in delivery flow.
Air in the pump
Will produce some of the same sign as cavitation but is not cavitation and will not damage the pump as it goes through at the same pressure as the water.
Purpose of flow gauges
To measure the amount of water flow through a pipe.
Operate via internal paddle wheel sensor.
Points to remember for throttle control
Always return to idle position at the completion of pump operations.
Use in conjunction with opening and closing deliveries and outlets to maintain correct kPa.
What will the emergency shutdown button do and how can you reset it
Emergency shutdown will stop engine and pressure to all deliveries will be lost. To reset: Reset emergency stop button. Return throttle to idle. Select neutral. Disengage pump and HP hose. Turn ignition off and wait 10 seconds, Restart engine. Engage pumps. Select 'D' on auto transmission. Re-commence pumping.
How to control gated valves
Should be operated in a smooth manner to avoid water hammer when opening and closing.
Watch pressure and adjust throttle to maintain correct kPa.
Can be slightly closed to keep pressure but limit volume, if tank is running out too fast.
When are drain valves used
Delivery drain valves are used to release the pressure from a charged line of hose when it cannot be done via the branch.
Pump drain valves are used to completely empty the main pump casing. (mainly for workshops)
Purpose of pump pressure gauge
Indicates the delivery pressure of water from the main pump to the 64mm deliveries and monitor. Of bourdon tube design.
Purpose of high pressure gauge
Indicated the delivery pressure of water from the high pressure pump to the 25mm high pressure hose reels.
Purpose of the compound gauge
Indicated the pressure of water entering the pump from closed water and also height of water being lifted from open supply.
Positive means water in on closed supply.
Negative mean overrun on closed supply.
0 when drafting mean so prime.
Negative when drafting means lift depth.
Describe the pressure relief valve
Primary function of the pressure relief valve is to prevent excessive delivery pressure to other lines when a hose line is shut off, or delivery valves are closed.
Is set to prevent excess delivery pressure. Only bleed of a maximum of 200kPa.
Not HP hose reels.
Supplementary pump cooling techniques
Open an unused high pressure delivery onto the ground.
Open an unused high pressure delivery into the tank filler.
Open branches regularly.
Connect a main delivery to the tank filler point.
Disengage the high pressure pump when not required.
Throttle back when high pressures are not required.
Supplementary pump cooling (‘P’ series Varley).
High pressure reel use will cool both HP and main pump.
Main pump use will only cool main pump.
Cooling bleed line amounts
P series Varley pumper has pump to tank valve switch and cool approx 60L/min.
P series Fraser pumper and series IV cool at approx 18L/min.
What happens if pump is operated without discharge
Pressure energy is converted into heat energy. Which can damage the pump. Use supplementary cooling techniques.
How will you know if the pressure relief valve is working
Illuminating of the green lamp, a slight drop in the pump rpm and the sound of water flow through the valve will indicate to the operator when the system in functioning.
Why would you fill the onboard water tank
Should be filled prior to closing tank to pump valve.
Ensure if the external supply is compromised the on board supply can be used until another supply can be connected.
Why may you notice a decrease in pressure in the compound gauge
Other users on the same main.
A branch being opened.
Kinks being taken out of a delivery hose line
Standpipe being partially turned off.
Weight applied to collector line or kinks in the collector line.
Fire ground calculation
High pressure hose reel
Rule: this will give you the L/min Drop the Zero Subtract 50kPa So at 2000kPa. Drop the zero =200 Subtract 50 = 150 Therefore will deliver at 150L/min With 1500L onboard divided by 150L/min Will last for 10 mins
Fire ground calculation
Friction loss
38mm hose loses 50kPa per 30m length.
64mm hose loses 20kPa per 30m length.
Each floor is assumed 3m
Add 10kPa per meter
Therefore each floor add 30kPa
So if you want 700kPa up 5 floors through 2 lengths of hose.
Friction loss = 2 x 50 = 100
Head pressure = 5 floors x 30kPa per floor = 150
Total = Branch + friction loss + head pressure
Total = 700 + 100 + 150 = 950kPa needed at pump.
Roof mounted monitor points to remember
Should be turned on and off when pump is at idle.
Can be used below the 35 degree, care should be taken where the stream is directed.
Ground mounted monitor points to remember
Must not use below 35 degree stop.
Use rotation lock unless redirecting.
Can be used with 1 or 2 delivery lines.
Loop lines around from and deliver from rear.
Should be tied off.
If monitor tilts during operation a safety restrictor valve is activated to reduce delivery flow.
How foam induction work
Eductors work on the principal of a high and low pressure system called the ‘Venturi System’. This is where water passing through an eductor creates a vacuum that allows foam concentrate to enter the eductor form an external source.
Methods used to supply concentrate
Two most common method are via an on-board tank supply or via 20 litre containers.
How external inline eductors work
External inline eductors rely on the venturi effect to induce foam through a pick up tube.
Require a minimum pressure differential between the inlet and outlet of 35% to create a venturi induction.
Standard operating pressure of 1400kPa.
Can be attached either at the panel or between hose lengths, the foam is then aerated at the branch.
Pumper foam capacities
Series IV and P series Varley pumpers have 130L onboard foam.
Fraser pumpers have 80L onboard foam.
Points to remember when using External inline eductors
Always operate with branch fully open.
Because all foam making is external of the pump, only the hose lines, eductors and branches need to be flushed after use.
Foam branch produces expansion rate of 10:1.
Foam and water can be delivered at the same time from separate deliveries.
Foam cant be delivered from HP reels or roof monitor.
Can be delivered through ground monitor.
Why do we use primers
Centrifugal pumps cannot pump air. Therefore if it is required to lift (draft from open water supply) we need a primer to exhaust the air before we try to pump.
Points to remember when priming
Use no longer than 45 seconds.
When drafting if compound gauge returns to zero you have lost prime.
Shut all deliveries and tank to pump valve before prime.
Prime first then engage pump.
If prime isn’t working must have air entering system.
How to operate primer
Pull the activation level and check for water discharge.
If the pump is not primed after 45 seconds, check for blocked vent, loose connections, blocked suction hose or an empty oil reservoir. Wait 2-3 minutes before trying again.
Once finished ensure lever if pushed firmly inward.
Points to remember when drafting
Maximum lift of 7M in ACT.
Refill onboard tank from tank fill point.
HP reel and roof monitor will work when drafting as everything works a normal just from different water supply.
Compound gauge will read negative. Every 10kPa will indicate 1m of lift.
Will over run at 70kPa.
Increase revs before opening deliveries and lower revs after closing deliveries to maintain prime.
Pump capacity rating is depend upon
The intake diameter. The impeller eye diameter. The impeller outside diameter. The width of the impeller. The shape and number of vanes on an impeller. The design of the volute chamber.
What is lift when drafting
Lift is when water is taken from an open water source below the inlet of the pump.
To achieve lift a partial vacuum is created within the pump chamber and suction hose.
Factors influencing amount of lift
Atmospheric pressure.
Over coming frictional loss. (keep hoses short)
Any restriction in the hose. (collapsed line)
Condition of the pump.
Density of the water.
Temperature of the water.
Good seals between connections.
How does a primer work
Pull lever to activate electric motor to spin rotor.
Rotor is off centre to casing.
As rotor spins blades fly outward and maintain contact with casing.
As volume expands creates low pressure system to suck air in and exhaust out.
When drafting if the compound gauge moves further in the negative it means
Deliveries have been opened.
Vertical lift is increasing.
Strainer blockage.
Blocked passage.
When drafting if the compound gauge moves towards zero.
Air entering system. Caused by: Loose connections. Bad seals. Suction inlet too close to top creating vortex. Pump casing leak.
Three types of relay pumping
Tanker relay
Open circuit relay
Closed circuit relay
Describe tanker relay
Used in rural situation where water source is far away.
Tankers are relayed to provide adequate supply to the fire ground.
Describe open circuit relay
Pump from source into portable dam.
The pump from that dam to next and so till you reach the fire ground.
Describe closed circuit relay
Pump through hose lines into the collector of the next pumper until fire ground is reached.
To help increase pressure.
Spacing between pumpers when relays depends on
The pumping capacity of individual pumps.
The difference in elevation between two pumps.
The number of lines being used.
Points to remember when relaying
Best pump first. (no advantage to higher capacity pump at the end)
Twin lines between where possible.
No more than 7 line spacing.
Release air from system when at each pump when charging.
Start at idle and gradually increase to 800kPa.
Pump operator to monitor panel at all times.
Base pump in charge of relay.
Why must suction line be ties off.
To control the height.
To take weight off the coupling.
To hold in optimal position.
