Roger Mardon fire service history

Fire service historian and author

Roger Mardon

www.romar.org.uk

The principle of the HVP system is to deliver volume not pressure and theoretically up to 8,000 litres (1,760 gallons) of water per minute can be discharged at the delivery end up to 3km away. For firefighting purposes this would normally be through 5-way manifolds supplying standard 70mm fire hose to feed pumping appliances on the fireground which, in turn, provide the pressure for firefighting jets. For pumping away flood water, discharge would be through open ended lines. While some big city appliances can pump twice as much, a typical fire appliance can pump 2,270 litres per minute (500 gallons) and in practice one HVP can move three times as much water as most standard fire engines. In comparison, a 1950s AFS emergency pump (Green Goddess) could pump 4090 l/min (900gpm). There were 3,000 of them but there are only 50 HVPUs.

Hose lines can be doubled or trebled as required and hose ramps can be positioned to enable traffic to cross the lines but only one set of ramps is carried for each kilometre of hose. The ramps comprise aluminium squeeze blocks which do not reduce the water flow through the hose lines.