Regulating Units Essay Example | Topics and Well Written Essays - 1000 words

Regulating Units - Essay Example A valve positioner is a device which exactly positions a control valve to the required position as per the signal given to it. Positioner senses the valve opening through a position feedback link connected to valve. Controlled external supply air to positioner provides power to positioner to position a valve. A globe valve is that in which inlet and outlet openings are arranged in several ways to suit varying requirements of flow. It can give straight flow, angular flow and cross flow. The major application is to get good flow control. Picture below: Ball valves are stop valves that use a ball to stop or start the flow of fluid. When operated, the ball rotates to a point where the hole through the ball is in line with the valve body inlet and outlet. Picture below: Gate valves are used when a straight-line flow of fluid and minimum restric ­tion is desired. The part that either stops or allows flow through the valve acts somewhat like the opening or closing of a gate and is called, the gate. Butterfly valves are used in a variety of systems aboard ship. These valves can be used effectively in freshwater and saltwater. It consists of a butterfly disc which when rotated determines the flow of liquid through it. It is used for Good flow control at high capacities. Valve positioners compare a control signal to a valve actuator’s position and move the actuator accordingly. The most modern valves come with following specifications. Deadband -