Control Valve top 7 interview Questions and Answers

For the Instrument engineer, the topic of the control valve is the most common and frequently asked question in the interview. So let's discuss the top 7 Questions and Answers. 

1. What is a control valve?

Control Valve is a final control element and it is used to control fluid flow by varying the size of the flow passages directed by a signal for control. A control valve consists of an actuator and a valve. The actuator provides the power to vary the position of money inside the plot.

2. What are the different types of control valve

Control valves are mainly divided into two parts. The first is depending on the action and the second is depending on the body. Depending on the action, there are two types. First is air to close and second is air to open and depending on the body, there are four types, first is Blofeld, single or double CD. The second is angle valves. The third is butterfly valves. And fourth is three-way valve third

3. What are the applications of air to close inherently open control valves?

There are three main applications of the Air to close the control valve Firstly, it is used in reflex lines. Secondly, it is used in cooling water lines and lastly, it is used in safety relief services.

4. What is Cv of about?

CV is the capacity of a valve and it is defined as the number of gallons per minute of water that passes through a fully open valve and a pressure drop of one pound per square inch.

5. Can you please explain the difference between a normally closed valve and a normally open valve?

First of all, let me explain what is normally a closed valve. As the name suggests, normally closed valves remain closed in a de-energized state and open when energized. On the other side, the normally open valve remains in an open and de-energized state and is closest when energized.

6. What is the positioner and what is the function of a positioner?

The positioner is a device that makes the valve open or close to eliminate the process error and achieve the setpoint by generating input signals. The function of the positioner is to measure the actual position of the valve and take the command from the controller compare both the signals and make the valve move either in an open direction or close direction to correct the process error

7. What does an actuator and what are the types of actuators?

the device which makes the valve to operate through different energy inputs like pneumatic, electric, hydraulic, etc.

There are mainly four types of actually first is pneumatic, second is pneumatic piston actuator, third is electric actuator and fourth is a hydraulic actuator.