Fire service historian and author
Coupling spanners are used to connect the Storz hose couplings by lining up the red
dots. A Y-piece, fitted with a pressure gauge, and gate valves are attached to the
hose adjacent to the Hydrosub so that the pump operator can control the flow, and
the hose is charged up to the Y-piece. Usually one leg will go to the incident and
one will be maintained as a drain off so pressure can be released between it and
the pump to prevent back flow. The operator must keep back flow to a minimum to avoid
reversing the impeller.
While all this is going on the driver of the prime mover repositions his vehicle
and, with his assistant, reloads the main HVP module with the hose box containing
1 kilometre of 150mm delivery hose - 20 x 50m lengths coupled and flaked in the bed
of the hose box. This hose can be paid out from the rear of the vehicle over a ramp
lowered from the back of the hose box and, once the crew are sure the hose is paying
out properly, the appliance can continue at up to 28mph. Each HVPU has a further
Duo container with two more hose boxes each containing 1km of hose.
