Water Supplies Flashcards
Describe Static supply
These are bodies of water such as dams, rivers, lakes, and swimming pools that are accessed by ‘draughting’. Static supplies are sometimes referred to as ‘open water’.
Describe Reticulated supply
This refers to water within a network of pipes ( mains ) which is accessed via various types of hydrants. reticulated water is sometimes referred to as ‘closed water’.
3 types of mains
Trunk mains Service mains Ring mains
Describe trunk mains
Trunk mains vary in size from 600mm to 3000mm. these mains deliver water from the source to the treatment plants and then on to the service reservoirs.
Describe service mains
Service mains form a network of pipes that feed the various pressure zones from the reservoir. They are laid underground and consumers draw water from them by means of smaller water pipes tapped in. Usually between roadway and footpath.
What does a shut-off valve do
Allow sections of the main to be isolated in case of breakage or repair. They can also be shut off in order to allow greater pressure and flow for ACTF&R units.
Describe pressure
Is the force at which water is delivered from the mains. Pressure is what pushes the water ( fluid ) through the lines and equipment. Usually measure in kPa ( kilopascals )
What affects pressure
The length of main between the pump, or other elevated pressure source such as reservoir, and the hydrant. Weather or not there are pumping stations/ boosters in the system. The number and size of hoses or appliances attached to the main. The quantity of water being used by other consumers.
Describe flow
Is the quantity of water being delivered in a given time. the volume of water ( fluid ), that flows through a passage 9 hose line ) of any given section during a unit of time. i.e litres per minute.
What affects flow
The diameter of the main. The condition of the internal surface of the main. Older mains may suffer from internal corrosion or tuberculation ( formation of mineral deposits ) which will affect the smoothness. The pressure at which the main is working.
Describe spring valve hydrants
Commonly referred to as ‘ball valve’ hydrants. Has a mushroom shaped valve, which is held onto the sealing washer by the pressure of a non-ferrous spring. Accessed via a standpipe.
3 mains types of hydrants
Spring valve hydrants High capacity hydrants Pillar hydrants
Describe high capacity hydrants
Supplies large volumes of water. Usually located in high risk areas such as hospitals, shopping centres, industrial areas, high density housing, schools and multi-storey buildings. Have 2 65mm storz couplings and 1 125mm storz coupling covered by blank caps, accessed by high capacity hydrant key. They are cast iron approx 800mm high and 400mm wide painted yellow for easy visibility. In some areas Icon water has replaced with a grouping of spring valves.
Describe pillar hydrants
Not normally installed anymore. Same are in use some are heritage listed with a spring valve at the base. The shut-off valve is fitted with a spindle on top of the riser that is opened by use of ‘pillar hydrant key’ or the fitted hand wheel.
Describe a stand pipe
A standpipe is a FF’s means of accessing spring valve hydrants. It has 2 65mm storz couplings and is capable of twin or single outlet flow by the use of the shut off handle. The lugs of the standpipe fit into the bayonet lugs of the spring valve and when screwed tightly puts pressure on the seal at the base. the hand wheel can then be rotated clockwise to extend a rod down the barrel, the rod then forces the valve off its seat to supply water.