Regardless of the type of valves used, all control valves which are stem-actuated require some kind of sealing material to permit stem motion through an external mechanism called an actuator. The sealing of process fluid doesn’t allow for any leakage between the moving stem and valve body. A sealing mechanism for a valve stem is …
A brief overview of temperature control valve: Temperature control valves (TCV) are known as De-super heaters, Attemperatures, or temperature regulators. They are referred to as common control elements used in the process control industry. Temperature control valves in process industries are an integral part of various applications, such as power generation units, oil and gas …
The control valve with a dead band behaves like there may be some kind of resistance or response between the output of the controller and the actual position of the stem in the valve actuator. When the direction of controller output is changed at any instant. The dead band needs to pass over before the …
Specification of a control valve begins with a control loop. The control loop in every industrial application includes transmitters to transmit the signal to the controller then to the positioner and finally to the actuator of the control valve. The valve assembly consists of : Positioner to convert electric signal to pneumatic signal. Actuator for …
How to specify control valves for process applications Read More »
In many process and industrial applications, the fundamental requirement is that a control valve must be able to control the flow rate or stop the complete flow of fluid in the fully closed position. In practice, most control valves still allow for the flow of fluid through the passage even when the valve is in …
What is a control valve flashing? When a process fluid has flowed through restriction of the control valve. There is an increase in the velocity of the process fluid. Flashing can be predicted by the Continuity equation The continuity equation states that “For any flow rate the product of fluid density, flow area, and its …
What is the controller action? The controller action is defined as the function of the controller. The controller action determines whether The controller output increases when PV increases above the set point, or The controller output decreases when the PV is increased above the set point. The operator has to select the controller action based …
Working of Direct Acting and Reverse Acting Control Valve Loop Read More »
Cavitation is a phenomenon that occurs in a control valve during sizing control valves for liquid flow applications. Cavitation in the valve occurs in fluid flow systems where the local static pressures are below the fluid’s vapor pressure. According to the Bernoulli equation the cavitation in the valve occurs when a fluid accelerates in a control valve …
The valve actuator is a part of the control valve assembly fitted to it. In any control loop, the valve actuator receives a control signal for the system to move the valve to either a fully open or fully closed position or to remain in an intermediate position depending upon the control signal used. The …
The control valve is a device meant to control the flow rate or flow direction of the fluid in the process. It is referred to as the final control element. This control valve will adjust the flow passage as directed by a signal controller to modify or control the flow rate. The basic and most …
