Abstract: A butterfly valve having a valve body and a valve disc which is rotated to produce an engagement with a peripheral edge of the disc and an annular seat or wall defined by a portion of an internal fluid passage in the valve body uses a seal ring member mounted in an annular groove in the valve body adjacent to the annular seat. The seal ring member includes a pair of bowed seal rings arranged in a "V" within a triangular shaped annular recess in the wall of the fluid passage in the valve body. One side, i.e., an inner side, of each of the seal rings projects from the triangular recess to contact the edge of the valve disc to form a fluid-tight seal in response to fluid pressure acting on a convex face of a seal ring to flatten the seal ring. The other side of each of the seal rings contacts a respective corner of the recess with the convex faces of the seal rings facing each other.

Abstract: A distance measuring apparatus and a differential pressure transmitter utilizing the same having an ultrasonic element reflector mounted between a pair of ultrasonic transducers. The alternate operation of the ultrasonic transducers produces a pair of transducer energizing signals which are related to the relative separation of the reflector element from the transducers. In one embodiment, the reflector element is mounted within a closed pressure vessel divided internally by an ultrasonic reflector diaphragm with a pair of fluid inlet lines admitting respective pressurized fluids to corresponding sides of the reflector diaphragm.

Abstract: A gas valve has a single operating knob for providing the operation of a pilot valve and the resetting operation of a thermocouple controlled safety apparatus with a "supersafe" operation. Specifically, the gas valve has a main operating shaft adapted for both axial and rotary movement by a control knob. A tilting latch is attached to the shaft to provide for operation of a pilot valve and a main safety valve when a thermocouple safety mechanism is energized both for a safety valve resetting operation and to provide a "supersafe" operation.