Water relay & water shuttle Flashcards
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Water relay & water shuttle
What size hose is used for water relaying by pumping appliances?
90mm hose and 70mm hose
Water relay & water shuttle
What is the maximum distance between pumps when using 90mm hose on level ground?
90mm hose - 15 lengths
Water relay & water shuttle
How far from the hydrant should the initial pump be?
As close as possible to receive maximum flow from hydrant, and no more than 3 lengths and always twinned. Every additional length reduces flow to pump.
Water relay & water shuttle
How do we connect 90mm to a pumping appliances?
90mm Storz hose tail adaptors
Water relay & water shuttle
What pressure should a water relay ideally run at and how many lights will be showing on the water tank contents indicator if the relay is balanced?
2 bar and 3 lights on the water tank indicator
Water relay & water shuttle
In a relay , when can you deliver on to the next appliance in the line?
Only when you are receiving the full delivery from the pump before you/hydrant supply.
Attempting to fill 8 lengths of twinned hose prior to receiving water will result in dumping the entire tank contents causing pump to go into prime mode. This is because the volume of water held in 16 lengths of hose is greater than that of the tank 1300l.
Water relay & water shuttle
How many lengths of twinned 90 mm hose can pumps be apart in a water relay on an uphill gradient ground?
12
Water relay & water shuttle
In a water relay which pump will determine the pressure supplied to the branch, monitor or aerial appliance?
The fire ground pump
Water relay & water shuttle
In what circumstance would water relay and water shuttle be required?
In some areas, water supplies are inadequate for firefighting, to overcome this we can use water relaying or water shuttle.
Water relay & water shuttle
When would you normally consider the use of water carrying?
Usually in rural areas where distances can be considerable and terrain difficult, water carrying may be the preffered option.
Water relay & water shuttle
How is water carrying normally carried out?
A number of appliances can be used to collect water from a source and deliver it to the tank of a fire ground appliance of a temporary dam which can then be used as an open water supply for a fireground pump.
This method of water supply is rarely used in London.
Water relay & water shuttle
What are the disadvantages of water carrying?
- has to be well managed
- supply is interuptable
- resource intensive
Water relay & water shuttle
What is a water relay?
Water relay comprises of a number of pumps spaced at intervals along a route between the water source and the fire ground pump.
Water relay & water shuttle
What is an open circuit water relay?
An open circuit water relay is when water is pumped through hose to open dams, reservoirs or the appliance tank before entering the inlet of the next pump.
This type of relay is used when employing major pumping appliances.
Water relay & water shuttle
What is a closed circuit water relay?
A closed circuit water relay is when water is pumped through hose directly from on epump to the next.
LPP’s are used for this type of relay.
Water relay
What considerations are made when setting up a water relay?
Maximising the quantity of water being delivered whilst reducing frictional losses. This is achieved by;
- using the largest hose possible
- twinning hose
- keeping the distance between pumps as short as possible
Water relay & water shuttle
What factors will influence the distance between pumps?
the flow required
the size of the hose
the contours of the relay route
Water relay & water shuttle
What role does the fire ground pump play in a water relay?
Once all appliances are connected, the fire ground pump begins with supplying water first to either monitors or jets. It can operate at up to 10bars (taking into account frictional losses).
- The fire ground pump operator opens their deliveries and increases engine revs to achieve required pressure
- The 4th tank level indicator will flicker the go out
- The fire ground pump operator then opens their inlet collecting head and orders the next intermediate pump to start supplying them with water at 2 bars
- They try to maintain 3 lights on the tank level indicator
Water relay & water shuttle
What role does the intermediate pump play in a water relay?
on recieving a request from the next appliance in the relay (working from fireground back):
- They will open their deliveries and begin pumping water at 2 bars.
- The 4th tank level indicator will go out
- The intermediate pump operator then opens their inlet collecting head and orders the next intermediate or base pump to start supplying them with water at 2 bars
- They try to maintain 3 lights on their tank level indicator
Water relay & water shuttle
What role does the base pump play in a water relay?
On recieving a water on requested from the appliance next in the relay, the base pump operator will:
- Open up deliveries and start supplying at 2 bar
- The 4th tank level indicator will go out
- open up the inlet gate valves (the flow meter will indicate what is coming in from the hydrant)
- Try to maintain 3 lights on the tank level indicator.
Remember: hydrant flow or water source will dictate what can be supplied to monitors !
Water relay & water shuttle
What should all pump operators remember when part of a water relay?
- If the autofill valve is opening & closing (4 lights), you are receiving too much water, this can result in water hammer, snaking and bursts in soft suction hose.
- Resrict the volume of water coming in by partially closing the inlet collecting head.
- If the tank level indicator lights are going out, you are delivering more than you are receiving, either open up the collecting head to receive more water or ruce the amount of water you are delivering.
If you are over running your supply, the only way to get balanced flow is to shut branches or get branch operators to reduce their flow settings on their branches.
You must inform the IC or Sector Commander !
Water relay & water shuttle
How is a closed circuit water relay initiated?
The fire ground LPP operator will determine the pressure and flow required having consulted with the operator of the branch or monitor.
On the orders of the IC, the base pump operator will prime the pump then supply water to the 1st intermediate pump and so on up to the fire ground.
If ‘water on’ is not required imediately, the base pump will close it delivery to maintain lift and all pumps will be swithched off awaiting the ‘water on’ command.
When ‘water on’ is received, the base pump operator will slowly increase pressure 1 bar at a time until 4 bar is reached (optimum pressure for an LPP).
As soon as each intermediate pump operator recieves their order for water on, they should adjust the throttle to just above zero on the compoiund gauge.
