Abstract: A double block valve and a valve proving system are disclosed. The double block valve is actuated by a single actuator and includes a valve body housing a cavity. The cavity defines an upstream portion with a fluid inlet and a downstream portion with a fluid outlet. A seating assembly is interposed between the upstream and the downstream portions. A first and a second blocking element are disposed in the valve body and are both movable within the cavity between opened and closed positions. With the first and second blocking elements both contacting the seating assembly, the space therebetween defines an enclosed space with a finite volume. The proving system is used for two safety shut-off valves on a valve train, such as a double block valve. The proving system connects to an enclosed space established between the two safety shut-off valves and includes a pair of three-way valves, oppositely biased pressure switches, and a pump, all of which are interconnected through pneumatic conduits.

Abstract: An extended range proportional valve which can control rates of mass flow over continuous low, intermediate and high ranges has a pilot member mounted on an armature of a solenoid which can be dithered onto and off of a pilot opening in a main valve member which seals a main valve opening to control mass flow rates over the low range by varying the duty cycle and/or frequency of a pulse width modulated current in the solenoid coil. Intermediate and high flow rates are achieved by dithering the pilot valve member with a duty cycle and/or frequency sufficient to raise the main valve member relatively short and relatively long respective distances from the main valve seat.

Abstract: A double block valve and a valve proving system are disclosed. The double block valve is actuated by a single actuator and includes a valve body housing a cavity. The cavity defines an upstream portion with a fluid inlet and a downstream portion with a fluid outlet. A seating assembly is interposed between the upstream and the downstream portions. A first and a second blocking element are disposed in the valve body and are both movable within the cavity between opened and closed positions. With the first and second blocking elements both contacting the seating assembly, the space therebetween defines an enclosed space with a finite volume. The proving system is used for two safety shut-off valves on a valve train, such as a double block valve. The proving system connects to an enclosed space established between the two safety shut-off valves and includes a pair of three-way valves, oppositely biased pressure switches, and a pump, all of which are interconnected through pneumatic conduits.

Abstract: A fitting for connecting two components is described. The fitting may be explosion proof for use in hazardous environments. The fitting may swivel allowing fast and easy connection to fixed components, thus minimizing the time required for installation and periodic maintenance, while maintaining the integrity of the explosion proof fitting. In this way, components—such as electrical conduits containing conductors or wires—can be installed and maintained without the use of damming material. Also described is a method of installing an explosion proof fitting for use in hazardous environments.

Abstract: A visual position indicator has a stator and a rotor with angularly displaced eccentricities for engaging corresponding spring biased actuators with magnets. Depending on the rotor position relative to the stator, one or more of the actuators is moved to a position whereat the field of its respective magnet can operate a magnetic switch disposed in a hermetically sealed housing. A decoder connected to the switches can produce a signal indicative of rotor position.