Hose

Question 1

Identify the different sizes of delivery hose used in HFRS

Answer 1

51mm 25m length

70mm 25m length

Question 2

State the characteristics of hose

Answer 2

Reliability in use - Capable of safe operation at the water pressures required, without fear of bursting, breaking or leaking

Handling and storage - Hose needs to be as lightweight as possible, capable of easy, neat coiling into a low diameter, stable coil when wet, dry and in all conditions.

Durability - durability and resistance to abrasion must be as high as possible due to rough usage in service. Must also be easily repairable.

Friction loss - BS6391 specifies a smooth internal lining surface to minimise friction losses.

Pressure and acceptance tests - must be capable of withstanding normal operating pressures and occasional fluctuations possibly exceeding 10 bar. Tested to burst pressure of 35 bar in short lengths and 22.5 bar at full length.

Question 3

State the size of hose reel tubing & it’s construction

Answer 3

Hose reel hose is non percolating delivery hose of 19mm internal diameter normal 20m in length with 6 lengths per engine (3 lengths per side) held together by Macdonald type couplings.

It is constructed of an inner rubber tube of lining, reinforced by wrapping layers of rubberised woven fabric applied spirally. An outer cover of abrasion resistant rubber is then applied and the whole thing vulcanised together.

Question 4

State the methods to prevent unnecessary damage to hose

Answer 4

Hose should be ramped when laid across a road

Hose should be charged slowly and not kinked under pressure

Hose must not be rolled or stored when frozen

Hose should be under run after use and preferably dried before storing

Question 5

List the characteristics of suction hose/hard suction

Answer 5

Resists external pressure

Exclusively used between water supply and pump

Smooth internal bore

Strong enough to withstand hydrant pressure

2.4m lengths in 100mm diameter with 100mm screw couplings