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Dual tank control system and method for use in foam introduction fire fighting systems

  • US 5,765,644 A
  • Filed: 09/06/1996
  • Issued: 06/16/1998
  • Est. Priority Date: 09/06/1996
  • Status: Expired due to Term
First Claim
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1. In a fire extinguishing system of the type including water supply means for normally delivering water at varying flow rates through a hose member, means for monitoring water flow through said hose member and producing an electrical signal related to a characteristic of the water flowing through said hose member, a first supply tank for containing a supply of a first liquid chemical foamant and having an output port coupled to first valve means, a second supply tank for containing a supply of a second liquid chemical foamant and having an output port coupled to second valve means, third valve means for selectively establishing a flow path between said water supply means and said first and second valve means, first level sensing means disposed within said first supply tank for generating a first level sensing signal corresponding to said first liquid chemical foamant reaching a predetermined level within said first supply tank, second level sensing means disposed within said second supply tank for generating a second level sensing signal corresponding to said second liquid chemical foamant reaching a predetermined level within said second supply tank, pump means having an input port coupled to said first and second valve means and an output port coupled to said hose member, sensing means for sensing a parameter corresponding to one of a speed at which said pump means is being driven and a flow of liquid chemical foamant being pumped from said pump means and generating a corresponding output signal, switch means for generating a switch status signal having a first state and a second state, computing means coupled to receive said electrical signal and said output signal from said pump speed sensing means, said computing means for determining a speed at which a variable speed electrical drive motor connected to said pump means should be driven to introduce a metered quantity of one of said first and second chemical foamant into said hose member and for generating a corresponding control signal to be applied to said drive motor, the improvement comprising:

  • (a) processor means coupled to said computing means and arranged to receive said first level sensing signal, said second level sensing signal, and said first status signal, said processor means for generating a valve driver actuation signal;

    (b) first valve driver means coupled to said processor means for selectively opening said first valve means;

    (c) second valve driver means coupled to said processor means for selectively opening said second valve means; and

    (d) third valve driver means coupled to said processor means for selectively opening said third valve means,whereby said processor means supplies said valve driver actuation signal to one of said first valve driver means, said second valve driver means, and said third valve driver means depending upon the state of said switch status signal to selectively introduce one of said first and second liquid chemical foamant into said water flowing within said hose member and to automatically flush said hose member with a quantity of water from said water supply means whenever said switch status signal changes between said first state and said second state.

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