Abstract: A waveguide for microwave radar level gages that includes a process sealed barrier in the waveguide that is impedance matched with bore transition sections of the waveguide at opposite ends thereof. The impedance matching results in positioning of the tapered end of the barrier offset from the ends of the bore transition sections.

Abstract: A process sealed waveguide is formed in a flange mounted on a tank, and is used for transmitting microwave energy from a source of microwave energy to an aperture of an antenna on the interior of the tank. The process sealed waveguide includes a mechanical barrier to prevent escape of fluid under pressure or liquid from the interior of the tank, and also serves to reduce impedance mismatch between the air, vapor, or liquid filled waveguide or antenna apertures. The flange is mated to the microwave source through an electronic housing to flange adapter that interfaces with the flange in a manner to provide a vent in case the mechanical barrier fails so pressure is released, and to provide flame quenching if flames are present. The adapter includes a second waveguide having a process sealed mechanical barrier mounted coaxially with the mechanical barrier in the waveguide in the flange.

Abstract: A microwave level gauge has a flange adaptor which includes a first end for coupling to a process connecting flange and a second end for coupling to an electronics housing. The adaptor has a section of reduced cross-sectional area along its length between the first and second ends, which defines a thermal transfer restriction that restricts heat transfer from the first end to the second end. A waveguide extends through the adaptor, from the first end to the second end.

Abstract: A level sensor for use in a process application measures height of a product in a tank. The level meter includes a microwave feedhorn directed into the tank, an electronics housing spaced apart from the feedhorn and a microwave waveguide extending therebetween. A microwave transducer in the housing couples to the waveguide and sends and receives microwave signals. A microprocessor in the housing identifies echoes from the microwave signals which are generated and sensed by the microwave transducer. The microprocessor determines height of the product based upon a microwave echo from the product and a microwave echo from the feedhorn. The microprocessor compensates for the effect of propagation delay through the waveguide on height measurements with the feedhorn echo and provides an output related to height of the product in the tank.

Abstract: A barrier device threadably mounts to a cabling aperture on a field mounted transmitter. The field mounted transmitter receives and transmits signals, and is wholly powered by a current loop circuit. The barrier device has a conductive housing with at least a first and a second aperture and a pair of conductors passing through the first aperture of the barrier device, for connecting to a terminal block in the transmitter. A pair of signal terminals, preferably as ring tongue lug, is mounted in the second aperture of the barrier device. The signal terminals are connectable to a handheld communicator, which is used to calibrate, monitor and test the transmitter. A barrier circuit is mounted in the housing and is electrically connected between the signal terminals and the conductors. Signals from the communicator access the terminal block through the barrier circuit, and the barrier circuit limits the power available at the signal terminals.