Compressed air foam system

• US 5,411,100 A
• Filed: 07/08/1993
• Issued: 05/02/1995
• Est. Priority Date: 10/01/1992
• Status: Expired due to Term

• Current Assignee: Hale Fire Pump Company
• Original Assignee: Hale Fire Pump Company
• Inventors: Teske, Richard E., Laskaris, Michael A.
• Primary Examiner(s): Pike, Andrew C.
• Application Number:
  US08/088,863
• Time in Patent Office: 663 Days
• Field of Search: 169/13, 169/14, 169/15, 169/24, 169/44
• US Class Current: 169/14
• CPC Class Codes: A62C 31/12 for delivering foam or atomised foam
• CPC Class Codes: A62C 5/02 of foam
• CPC Class Codes: B05B 7/32 the fed liquid or other fluent material being under pressure
• CPC Class Codes: G05D 11/132 by controlling the flow of the individual components G05D11/133 takes precedence

Abstract

A system supplies compressed air and foam to produce a fire stream comprising an aerated foam. The system includes a fire pump, an air compressor, a mixer, and a controller for automatically maintaining a desired ratio of air and water delivered from the mixer to a fire stream delivery device. An electronic control unit is arranged to sense both the flow rate of the water delivered by the fire pump and the air flow rate delivered by the air compressor, and modulates an air pressure signal used to vary the flow of air to the inlet of the air compressor so as to hold the air flow rate and the water flow rate at the desired ratio.

Claims

1. A system for supplying compressed air and foam solution to produce a fire stream comprising an aerated foam, said system comprising

a mixing means having a foam solution inlet, a discharge, and an air inlet,

a fire stream delivery means constructed and arranged to receive fluid flow from the discharge of said mixing means,

a fire pump for delivering water under pressure from a discharge thereof,

a water supply conduit means for delivering water from the discharge of said pump to the foam solution inlet of said mixing means,

water flow sensing means for sensing a flow rate of the water flowing through said water supply conduit means,

a foam proportioner for delivering foam chemical into the water delivered by said water supply conduit means for making the foam solution,

air conduit means for delivering the air to said air inlet of said mixing means,

air flow sensing means for sensing a flow rate of the air flowing through said air conduit means,

an air compressor for delivering the air at a discharge pressure to said air conduit means, said compressor having an inlet and a discharge,

an inlet throttling valve means for varying a flow of air to said compressor inlet to thereby control the compressor discharge pressure, said inlet throttling valve means having a control chamber and a valve member responsive to pressure in said control chamber for varying the flow of air to said compressor inlet, and

air flow control means for regulating the pressure of the air supplied to said control chamber of said inlet throttling valve means in accordance with the flow rate of the water sensed by said water flow sensing means and the flow rate of the air sensed by said air flow sensing means to automatically maintain the said flow rate of the air at a desired relationship to said flow rate of the water.

2. A system for supplying compressed air and foam solution to produce a fire stream comprising an aerated foam, said system comprising

means for mixing the air and the foam solution having a foam solution inlet, a discharge, and an air inlet,

a fire stream delivery means constructed and arranged to receive fluid flow from the discharge of said mixing means,

a fire pump means for delivering water under pressure from a discharge thereof,

a water supply conduit means for delivering the water from the discharge of said pump means to the foam solution inlet of said mixing means,

a foam proportioner for delivering foam chemical into the water delivered by said water supply conduit means for making the foam solution,

air conduit means for delivering the air to said air inlet of said mixing means,

an air compressor for delivering the air at a discharge pressure to said air conduit means, said compressor having an inlet and a discharge, and

control means for automatically maintaining a set ratio of air flow to water flow to said mixing means including

an inlet throttling valve means for varying a flow of air to said compressor inlet to thereby control a compressor discharge air flow rate, said inlet throttling valve means having a control chamber and a valve member responsive to pressure in said control chamber for varying the flow of air to said compressor inlet,

air control means for regulating the pressure of the air supplied to said control chamber of said inlet throttling valve means including

an air pressure regulator means having an air inlet means, an air outlet means, and a control means for varying an air outlet pressure of said air pressure regulator means,

a first conduit means for communicating the compressor discharge pressure to said air inlet means of said air pressure regulator means, and

a second conduit means for communicating the air outlet pressure of said air pressure regulator means to said control chamber of said inlet throttling valve means, and

an electronic control unit for delivering control signals to said control means of said air pressure regulator means to vary the outlet pressure thereof,

said air control means being constructed and arranged to vary the pressure of the air communicated by said second conduit means to said control chamber of said inlet throttling valve means to regulate the flow rate of the air delivered to said air inlet of said mixing means in accordance with the flow rate of the water delivered by said fire pump means to automatically maintain the rates of air flow and water flow to said mixing means at a desired relationship.

3. A system according to claim 2 comprising a pressure relief valve means having an inlet and a relief discharge, and conduit means for connecting the inlet of said pressure relief valve means to sense the discharge pressure of said air compressor and conduit means for connecting the discharge of said pressure relief valve means to said second conduit means connected to said control chamber of said inlet throttling valve means, said pressure relief valve means being constructed and arranged to deliver a pressure through said relief discharge thereof and said second conduit means connected to said inlet throttling valve means to close the same and block inlet flow to the compressor to thereby maintain the air pressure in the system at a desired pressure.

4. A system according to claim 2 comprising an air safety interlock means including

an air control valve for controlling flow through said air conduit means and being actuatable between a closed position blocking flow through said air conduit means and an open position permitting flow through said air conduit means, and

means for actuating said air control valve from said closed position to said open position in response to the sensing of the operation of both said fire pump means to deliver the water under pressure to the discharge thereof and said foam proportioner to deliver the foam chemical to said water supply conduit means.

5. A system according to claim 2 wherein said air pressure regulator means includes an air pressure regulator comprising a regulator air inlet, a regulator air outlet, a regulator water inlet, a regulator pilot air inlet, a regulator valve member operable for controlling the flow of air from said regulator air inlet to said regulator air outlet, a valve stem operatively connected to said regulator valve member for causing movement thereof, an air pressure responsive means operatively connected to said valve stem, a water pressure responsive means operatively connected to said valve stem, said water pressure responsive means being responsive to the pressure of the water delivered to said air pressure regulator through said regulator water inlet to actuate said valve stem in a first direction, said air pressure responsive means being responsive to the pressure of the air delivered to said air pressure regulator through said regulator air inlet for actuating said valve stem in a second direction opposite to said first direction, and a pilot air pressure responsive means operatively connected to said valve stem and constructed and arranged to be responsive to the air pressure delivered to said air pressure regulator through said regulator pilot air inlet to actuate said valve stem to cause movement of said regulator valve member.

6. A system according to claim 5 including a manual air pressure regulator having an inlet and an outlet and constructed and arranged to be manually set at a manual setting for regulating the pressure of the air supplied to said control chamber of said inlet throttling valve means in accordance with said manual setting, and selector valve means for communicating the compressor discharge pressure from said first conduit means to said inlet of said manual pressure regulator or to said regulator air inlet of said air pressure regulator of said air pressure regulator means.

7. A system according to claim 5 wherein said air pressure regulator means includes a pilot air flow control valve for controlling the air pressure delivered to said regulator pilot air inlet.

8. A system according to claim 5 wherein said air pressure regulator means is constructed and arranged to position said regulator valve member to a standby control position when no air pressure is delivered through said regulator pilot air inlet to cause movement of said regulator valve member.

9. A system according to claim 8 wherein in said standby control position said air pressure regulator means is constructed and arranged to deliver an outlet pressure to said control chamber of said inlet throttling valve means to shut off the flow of the air to said compressor inlet.