Water Supplies

Question 1

Water Supplies:

Describe Static supply

Answer 1

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’.

Question 2

Water Supplies:

Describe Reticulated supply

Answer 2

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’.

Question 3

Water Supplies:

3 types of mains

Answer 3

Trunk mains

Service mains

Ring mains

Question 4

Water Supplies:

Describe trunk mains

Answer 4

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.

Question 5

Water Supplies:

Describe service mains

Answer 5

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. In residential areas usually 100mm, in business and industrial areas between 150mm and 600mm.

Question 6

Water Supplies:

What does a shut-off valve do

Answer 6

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.

Question 7

Water Supplies:

Describe pressure

Answer 7

Is the force at which water is delivered from the mains. Pressure is what pushes the water (fluid) through the lines and equipment. Usually measured in kPa (kilopascals)

Question 8

Water Supplies:

What affects pressure

Answer 8

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.

Question 9

Water Supplies:

Describe flow

Answer 9

Is the quantity of water being delivered in a given time. The volume of water (fluid), that flows through a passage (hose line) of any given section during a unit of time. i.e litres per minute.

Question 10

Water Supplies:

What affects flow

Answer 10

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.

Question 11

Water Supplies:

Describe spring valve hydrants

Answer 11

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.

Question 12

Water Supplies:

3 mains types of hydrants

Answer 12

Spring valve hydrants

High capacity hydrants

Pillar hydrants

Question 13

Water Supplies:

Describe high capacity hydrants

Answer 13

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.

Question 14

Water Supplies:

Describe pillar hydrants

Answer 14

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.

Question 15

Water Supplies:

Describe a stand pipe

Answer 15

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.

Question 16

Water Supplies:

What is water hammer

Answer 16

If water flow is suddenly cut off, its kinetic energy is converted into pressure energy that must be absorbed by the pipe and fittings. This shock, and the pressure waves that it generates, is transmitted through the column of water and gives rise to what is known as water hammer. Water hammer can be so great as to rupture hose joints, hydrants, water mains or pump casing.

Question 17

Water Supplies:

How to avoid water hammer

Answer 17

Shut off branches smoothly and steadily.

Close hydrants smoothly and steadily.

Shut off deliveries and collectors at the pump smoothly and steadily.

If vehicles must be driven over charged line of hose, ensure that it is done very slowly. And use ramps where available.

Question 18

Water Supplies:

How is a hydrant indicated

Answer 18

By a ‘FH’ embossed metal plate affixed to the gutter. On the road adjacent is a blue ‘cats-eye’ usually located next to the centre line on the side that the hydrant is located. A small arrow may also be printed on the ‘cats-eye’ pointing to the hydrant.

Question 19

Water Supplies:

Hydrant positioning

Answer 19

Hydrants are located at 60-90m intervals in residential areas.

Larger shopping centres or industrial areas will have a high capacity hydrant every 135m with spring valve hydrants interspersed every 45m.

On roads with mains where only vehicle fires are apparent every 180m.

Question 20

Water Supplies:

What ways can hydrant booster systems be configured

Answer 20

Internal hydrant booster system

Attack hydrant booster system

Sprinkler booster system

Combined sprinkler and hydrant booster system

Question 21

Water Supplies:

Where would you find hydrant booster systems

Answer 21

As a general rule on thumb, any building of two or more levels (above or below ground) must have a booster system connected to the internal hydrant system.

Question 22

Water Supplies:

Where would you find internal hydrants pre 1994

Answer 22

Will be located no more than 4m from any designated exit.

Question 23

Water Supplies:

Where would you find internal hydrants post 1994

Answer 23

Inside a fire-isolated stairwell.

Question 24

Water Supplies:

What’s inside a booster cabinet

Answer 24

Connection points which allow FF’s to connect to internal hydrant system to boost pressure.

Some systems have their own pumps.

Usually twin 65mm storz with a pressure gauge above stating operating pressure.

Access to mains supply is next to boost-able storz couplings or close by.

Block plan.

Sign with maximum test and operating pressures.

Question 25

Water Supplies:

Describe attack hydrants

Answer 25

Internal and external attack hydrants can be seen as a network of ‘pre-laid’ hose to assist in the ease and speed of firefighting operations.

Firefighting operations can commence straight from the hydrant with no need to connect to a pumper.

Question 26

Water Supplies:

How much coverage must attack hydrants have

Answer 26

Internal attack hydrants must cover all internal areas with a 10m hose stream from a 30m hose.

External attack hydrants must provide coverage to all portions of the building with a 10m stream from a 60m hose and a minimum of 1m of hose access into any room served by the installation.

Question 27

Water Supplies:

Describe ring mains

Answer 27

In areas of high fire rish such as fuel depots, water mains are run completely around the risk then coupled back into the water supply.

Because water flows both ways possible flow is increased. If one side is damaged the loop will still allow flow through the other side.