Abstract: A ring-jet sensor (24) which is operated with air and is connected to an air-carrying line (23) is directed at the objects (27). The ring-jet sensor (24) is also coupled to a pressure sensor (37), the signal of which passes to a counter (40). In order to avoid connecting two lines to the ring-jet sensor (24), the said ring-jet sensor and also the pressure sensor (37), are each connected, in parallel, to one branch line (23, 35). The branch lines (23, 35) can carry either compressed air or suction air.

Abstract: Safety apparatus for an electrohydraulic servovalve. The safety apparatus includes a digital programmable switch (14) which is programmed to make switching decisions on the basis of whether or not the electrohydraulic servovalve is subjected to an external error and whether or not the electrohydraulic servovalve is free from internal error. Logic inputs that supply this information are provided to the programmable switch (14) by a logic device (16). On the basis of the logic inputs, the programmable switch (14) is programmed to interconnect, in a sequential manner, the analog electrohydraulic servovalve to one of four different analog drive systems. One of the drive systems is employed for the case whether there is no external or internal error, so that the electrohydraulic servovalve is in a normal mode of operation. Two of the drive systems are employed to quickly and safely de-energize the electrohydraulic servovalve upon the occurrence of an external error.

Abstract: A pneumatic pressure averager primarily for use in connection with aircraft instrumentation, which provides for three pressure outputs available from two pressure sources. Two of the outputs represent the input pressures directly, and the third output represents the average of the pressure from the two separate input sources.

Abstract: An enthalpy comparator for comparing the enthalpies of two bodies of air is disclosed having a first temperature sensor and a first humidity sensor for sensing the temperature and humidity respectively of the first body of air, a second temperature sensor and a second humidity sensor for sensing the temperature and humidity respectively of the second body of air, and a diaphragm module unit having a first diaphragm defined chamber connected to the first temperature sensor, a second diaphragm defined chamber connected to the second temperature sensor, a third diaphragm defined chamber connected to the first humidity sensor, and a fourth diaphragm defined chamber connected to the second humidity sensor, and an output sensing mechanism associated with the four chambers for providing an output dependent upon the enthalpies of the first and second bodies of air, and, in particular, the difference between the enthalpies of the first and second bodies of air.

Abstract: 1.