Abstract: Fire fighting equipment uses an electronically controlled direct injection foam delivery system. A water pump pumps water through a pipe. A foam pump pumps foam into a mixing chamber within the pipe to produce a water-foam mixture. A microprocessor-based control unit controls the water pump and foam pump. A conductivity sensor is coupled in-line with the pipe for monitoring conductivity of the mixture and providing a feedback signal to the control unit to regulate the foam pump. A speed sensor monitors the foam usage. The conductivity sensor uses stainless steel plates positioned in the flow stream of the pipe for measuring conductivity of the mixture. A second conductivity sensor monitors conductivity of the water and provides a feedback signal to the control unit. An interface circuit generates a voltage having dual polarity and a fifty percent duty cycle for the conductivity sensors.

Abstract: Fire fighting equipment uses an electronically controlled direct injection foam delivery system. A water pump pumps water through a pipe. A foam pump pumps foam into a mixing chamber within the pipe to produce a water-foam mixture. A microprocessor-based control unit controls the water pump and foam pump. A conductivity sensor is coupled in-line with the pipe for monitoring conductivity of the mixture and providing a feedback signal to the control unit to regulate the foam pump. A speed sensor monitors the foam usage. A second conductivity sensor monitors conductivity of the water and provides a feedback signal to the control unit. The foam delivery system can be controlled by monitoring the flow rate of the water and regulating the foam pump to maintain a constant water and foam mixture. A temperature sensor compensates the regulation process for changes in water and foam mixture temperature.

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.

Abstract: An improved white manganese bronze alloy containing, in weight percent, about 1.0-3.0 wt % aluminum, about 2.0-4.0 wt % bismuth, about 53-59 wt % copper, about 0.8-2.0 wt % iron, about 11-15 wt % manganese, about 5.0-7.0 wt % nickel, about 1.3-2.5 wt % tin, and about 18-24 wt % zinc, as well as incidental amounts of antimony, lead, phosphorus, silicon and sulfur, which is able to withstand vigorous cleaning and disinfection, and is not subject to galling.