US 5,494,112 AGranted

System for introduction of concentrated liquid chemical foamant into a water stream for fighting fires

AssigneeHypro Corporation

InventorsLawrence C. Arvidson, Robert S. Horeck

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Abstract

A fire fighting system introduces a liquid chemical foam concentrate into a water stream. The system may incorporate either or both of a hydraulic motor driven pump under control of a microprocessor-based hydraulic valve driver and an electric motor driven pump under control of a DC motor drive circuit. The DC motor drive circuit is adapted to be connected in electrical communication with the hydraulic valve driver and with a display/controller also incorporating a microprocessor. When operating in the dual mode, when the quantity of chemical foamant that must be added to the water stream to maintain a desired percentage mixture exceeds the capacity of the electric motor driven foam pump, control is transferred, via the hydraulic valve driver, to allow a hydraulic motor to drive a separate foam pump. In this fashion, the electric motor driven foam pump can cover a first range of flow rates from a very low rate to an intermediate rate and the hydraulic system then taking over to extend the range from the intermediate flow rate to a relatively high flow rate.

Claims13

Dependent claims

A fire extinguishing system of the type including means for injecting metered quantities of a liquid chemical foamant into a hose assembly conveying a water stream of variable flow rate so as to maintain a desired concentration of said chemical foamant in said water stream exiting said hose assembly over a wide range of water flow rates, said system comprising, in combination:

(a) tank means for holding a quantity of said liquid chemical foamant;
(b) first and second foam pumps, each having an inlet port and an outlet port, said inlet ports being coupled to said tank means and said outlet ports being coupled to said hose assembly;
(c) an electric motor for driving said first foam pump;
(d) a hydraulic motor for driving said second foam pump;
(e) a sensor operatively coupled to said hose assembly to sense a characteristic of the water stream flowing through said hose assembly and produce an electrical signal proportional to the sensed characteristic;
and
(f) electronic control means responsive to said electrical signal for driving said electric motor when a volume rate of flow of said chemical foamant to be added to said water stream to maintain said desired concentration is below a first threshold and for driving said hydraulic motor when said volume rate of flow of said chemical foamant to be added to said water stream to maintain said desired concentration is above said first threshold.

4 more elements

A fire extinguishing system of the type including means for injecting metered quantities of a liquid chemical foamant into a hose assembly conveying a water stream so as to maintain a desired concentration of said chemical foamant in said water stream exiting said hose assembly over a wide range of water flow rates through the hose assembly, said system comprising in combination:

(a) tank means for holding a quantity of said liquid chemical foamant;
(b) at least one foam pump having an inlet port coupled to said tank and an outlet port coupled to said hose assembly;
(c) a hydraulic motor connected in driving relation to said one foam pump;
(d) a hydraulic servo valve coupled in series circuit relation with said hydraulic motor and a source of pressurized hydraulic fluid;
(e) a sensor operatively coupled to said hose assembly to sense a characteristic of the water stream flowing through said hose assembly and producing a first electrical signal indicative thereof;
and
(f) control means responsive to said first electrical signal and a volume rate of liquid chemical foamant flow through said outlet port for producing a second electrical signal for modulating a speed at which said hydraulic motor is driving said foam pump, such that a desired quantity of the liquid chemical foamant in the water stream exiting said hose assembly maintains said desired concentration.

4 more elements

Dependencies are inferred from the claim text.