Patent ID: 8002203

Claim:
Proportioning apparatus for fire fighting systems, comprising: a housing having an adjustable water passageway adapted to be connected to a source of pressurized water and creating a pressure drop in the system; an adjustable fire fighting foam concentrate passageway adapted to be connected to a source of fire fighting foam concentrate and communicating with water from the water passageway effectively proximate a pressure drop; the foam concentrate passageway connected to the water passageway to adjust in concert; a pilot valve in fluid communication with water pressure upstream and downstream of the adjustable water passageway, the valve structured to automatically effect an adjustment of the water passageway to maintain a pre-selected pressure drop; and wherein the adjustable water passageway includes a dual acting baffle piston, the baffle piston having a first side in fluid communication with upstream water pressure and a second side in fluid communication, through the pilot valve, with, alternatively, upstream water pressure and downstream water pressure.