Water Relay

Question 1

Open circuit

Answer 1

The base pump takes water from the source and pumps it to some form of reservoir (fire service dam). Another pump then lifts the water from the reservoir and delivers it to a following reservoir. This continues until the water reaches the discharge point (final pump).

Question 2

Closed circuit

Answer 2

The base pump takes water from the source and pumps it to the next pump. This is connected to the inlet (collecting head) of the booster pump. The booster pump delivers water to the next booster pump and so on until the water reaches its discharge point.

Question 3

Distance

Answer 3

●The flow required
●The pump pressure employed (generally 7 bar)
●The size and type of hose and the number of hose lines between pumps
●The contours of the relay route
•uphill pumps must be closer together
•downhill pumps can be further apart.

Question 4

Twinning the lines

Answer 4

●If a hose line is twinned, the flow rate in each line will halve. Consequently, the friction loss will be reduced to a quarter of its former value.

Therefore, with twinned lines of hose, the distance between pumps may be four times as great as is with a single line.

Question 5

Base to booster

Answer 5

Single line 7 lengths

Twinned line 28 lengths

Question 6

Booster to booster / fire

Answer 6

Single line 9 lengths

Twinned line 36 lengths