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

  • US 5,494,112 A
  • Filed: 10/29/1993
  • Issued: 02/27/1996
  • Est. Priority Date: 10/29/1993
  • Status: Expired due to Term
First Claim
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1. 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.

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