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

• US 5,174,383 A
• Filed: 09/08/1988
• Issued: 12/29/1992
• Est. Priority Date: 09/08/1988
• Status: Expired due to Term

• Current Assignee: Sta-Rite Industries LLC (Pentair Plc (Ireland))
• Original Assignee: HY-PRO Corporation (Donaldson Company Incorporated)
• Inventors: Haugen, Roger A., O'Dougherty, Michael D.
• Primary Examiner(s): Focarino, Margaret A.
• Assistant Examiner(s): KANNOFSKY, JAMES
• Application Number:
  US07/241,462
• Time in Patent Office: 1,573 Days
• Field of Search: 169/44, 169/49, 169/5, 169/13-16, 169/24, 222/57, 239/61, 239/343, 137/88, 137/92, 137/3
• US Class Current: 169/15
• CPC Class Codes: A62C 5/02 of foam
• CPC Class Codes: G05D 11/132 by controlling the flow of the individual components G05D11/133 takes precedence
• CPC Class Codes: Y10S 261/26 Foam

Abstract

Fire-fighting apparatus and the method of using of same in which water from a supply source is adapted to be pumped at high pressure and predetermined flow rates through a fire hose and in which metered quantities of a chemical foamant are injected into the fire hose and mixed with the water stream to increase the effectiveness of the mixture as a fire extinguishant. A special purpose computer module is configured to monitor the flow rate of the water through the hose, the level of chemical foamant in a supply reservoir and the speed of the positive displacement pump used to inject the foamant. The computer then determines an appropriate speed for the pump and provides a closed-loop control signal to the pump'"'"'s drive motor to maintain a desired chemical injection rate.

Claims

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.

2. The apparatus as in claim 1 wherein the means coupling said output port of said pump to said hose member includes a check valve for preventing water from said water supply means from reaching said pump means.

3. The apparatus as in claim 1 and further including means for sensing the level of the liquid foamant in said supply tank, said level sensing means providing a further control input to said computing means.

4. The apparatus as in claim 3 further comprising means for shutting down said pump in response to the sensing of no liquid foamant in said supply tank by said means for sensing the foamant level.

5. 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.

6. The method of claim 5 further comprising the step of preventing the introduction of chemical foamant when said flow rate of said water is less than a predetermined minimum.

7. The method of claim 5 further comprising the steps of monitoring the supply of said chemical foamant and shutting down said pump means when said supply is exhausted.

8. The method of claim 5 further comprising the step of varying the output of said pump with respect to said computed quantity.