Apparatus and method for controlling the introduction of chemical foamant into water stream in fire-fighting equipment

Claim 1

Apparatus for injecting a foamant chemical into a water stream used in extinguishing fires comprising, in combination: (a) water supply means for normally delivering water at varying flow rates through a hose member; (b) means for monitoring the flow of water through said hose member and producing an electrical signal related to the rate of water flow through said hose member; (c) a supply tank for containing a supply of a liquid chemical foamant; (d) positive displacement piston pump means having a variable stroke and, having an input port coupled to said supply tank, an output port and pump speed sensing means for sensing the speed at which said pump is being driven; (e) means coupling said output port of said pump to said hose member; (f) a variable speed electrical motor means for driving said pump means at a speed determined by a control signal applied thereto; (g) computing means coupled to receive said electrical signal relating to flow, and a signal from said pump speed sensing means, said computing means determining the speed at which said motor should be driven to introduce a metered quantity of said chemical foamant into said hose member, depending on the rate of flow of water through said hose member; (h) means connecting said computing means in driving relation to said motor means; and (i) calibration means for calibrating the actual pump output in relation to said metered quantity.

Claim 6

A method of operating a fire-fighting system, comprising the steps of: (a) providing a primary supply of water; (b) delivering water from the supply to the site of a fire through a fire hose; (c) monitoring the flow rate of water flowing from said supply through said fire hose; (d) providing a supply of a chemical foamant; (e) computing the appropriate quantity of said chemical foamant to be introduced into the water stream from an instantaneous flow rate of said water; and (f) introducing controlled, time variable quantities of said chemical foamant into the water flowing through said fire hose by means of a variable-speed, motor-driven, positive-displacement pump in fluid communication with said supply of chemical foamant and said fire hose wherein the driven speed of the variable-speed motor is time varied as a function of the water flow rate through said introduction and wherein the positive displacement pump is a piston pump in which the piston stroke is adjustable to establish a precise predetermined volume of chemical foamant added to the water flowing in said fire hose per cycle of said pump.

Claim 7

A method of operating a fire-fighting system, comprising the steps of: (a) providing a primary supply of water; (b) delivering water from the supply to the site of a fire through a fire hose; (c) monitoring the flow rate of water flowing from said supply through said fire hose; (d) providing a supply of a chemical foamant; (e) computing the appropriate quantity of said chemical foamant to be introduced into the water stream from an instantaneous flow rate of said water; and (f) introducing controlled, time variable quantities of said chemical foamant into the water flowing through said fire hose by means of a variable-speed, motor-driven, positive-displacement pump in fluid communication with said supply of chemical foamant and said fire hose wherein the driven speed of the variable-speed motor is time varied as a function of the water flow rate through said introduction and wherein the positive displacement pump is a piston pump in which the piston stroke is adjustable to establish a precise predetermined volume of chemical foamant added to the water flowing in said fire hose per cycle of said pump.