Electronically controlled direct injection foam delivery system and method of regulating flow of foam into water stream based on conductivity measure
First Claim
1. A unit of fire fighting equipment having a direct injection foam delivery system, comprising:
- a water pump for pumping water through a pipe;
a foam pump coupled to the pipe for mixing foam with the water and producing a mixture;
a control circuit for controlling the foam pump; and
a first conductivity sensor coupled in-line with the pipe for monitoring conductivity of the mixture and providing a mixture conductivity signal to the control circuit to regulate the foam pump.
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Accused Products
Abstract
Fire fighting equipment uses an electronically controlled direct injection foam delivery system (10). A water pump (14) pumps water through a pipe (24). A foam pump (36) pumps foam into a mixing chamber (46) within the pipe to produce a water-foam mixture. A microprocessor-based control circuit (20) controls the water pump and foam pump. A conductivity sensor (50) is coupled in-line with the pipe for monitoring conductivity of the mixture and providing a feedback signal to the control circuit to regulate the foam pump. The conductivity sensor uses stainless steel plates (60,62) positioned in the flow stream of the pipe for measuring conductivity of the mixture. An interface circuit (54) generates a voltage having dual polarity and a fifty percent duty cycle for the conductivity sensor. A second conductivity sensor (30) monitors conductivity of the water and provides a feedback signal to the control circuit.
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Citations
27 Claims
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1. A unit of fire fighting equipment having a direct injection foam delivery system, comprising:
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a water pump for pumping water through a pipe;
a foam pump coupled to the pipe for mixing foam with the water and producing a mixture;
a control circuit for controlling the foam pump; and
a first conductivity sensor coupled in-line with the pipe for monitoring conductivity of the mixture and providing a mixture conductivity signal to the control circuit to regulate the foam pump. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A mixing system, comprising:
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a pump for directing a chemical agent into a pipe for mixing with a liquid and producing a mixture;
a control circuit for controlling the pump; and
a first conductivity sensor coupled to the pipe for monitoring conductivity of the mixture and providing a mixture conductivity signal to the control circuit to regulate the pump. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A system for mixing first and second fluids, comprising:
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a conduit for transporting the first under pressure, wherein the second fluid is injected into the conduit for producing a mixture of the first and second fluids;
a control circuit for controlling a flow rate of the second fluid; and
a first conductivity sensor for monitoring conductivity of the mixture and providing a mixture conductivity signal to the control circuit. - View Dependent Claims (20, 21, 22, 23)
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24. A method of mixing first and second fluids, comprising:
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transporting a first fluid through a conduit under pressure;
mixing a second fluid with the first fluid to produce a mixture;
sensing conductivity of the mixture; and
regulating flow of the second fluid in response to the sensed conductivity of the mixture. - View Dependent Claims (25, 26, 27)
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Specification