Abstract: A pneumatic actuator having AND gate logic characteristics is disclosed. The actuator has three chambers each divided into two chamber portions by respective flexible diaphragms. One of the diaphragms acts as a valve closing member and controls the flow of a pressurized fluid through the actuator to actuate an associated device when fluid flow is permitted. The other two diaphragms are in mechanical contact with one another and in hydraulic communication with the one diaphragm and thereby control its motion, keeping it normally closed and preventing fluid flow but allowing it to move into an open position permitting fluid flow and actuation of the associated device only when each of the two diaphragms are subject to separate, concurrent drops in pressure which allows both of them to deflect away from the one diaphragm.

Abstract: A pneumatic actuator having AND gate logic characteristics is disclosed. The actuator has three chambers each divided into two chamber portions by respective flexible diaphragms. One of the diaphragms acts as a valve closing member and controls the flow of a pressurized fluid through the actuator to actuate an associated device when fluid flow is permitted. The other two diaphragms are in mechanical contact with one another and in hydraulic communication with the one diaphragm and thereby control its motion, keeping it normally closed and preventing fluid flow but allowing it to move into an open position permitting fluid flow and actuation of the associated device only when each of the two diaphragms are subject to separate, concurrent drops in pressure which allows both of them to deflect away from the one diaphragm.