VALVES || Instrumentation || Interview Questions and Answers on Valves

basic interview questions and answers on valves
today we will discuss about basic interview questions and answers on valves
1)What is a Valve?
A valve is a device that controls the flow of a fluid or gas. Today’s valves can control not only the flow, but the rate, the volume, the pressure or the direction of liquids, gasses or slurries through a pipeline.
2)What is a control valve?
Control valve is final control element in the process control industry. It handles flowing fluid like Steam, Gas, Water, Liquids to set right the process errors and regulate the process as per the desired set point.
3)What are the most important parts of a control valve?
Body, Bonnet, Trim (Seat ring, Plug and Spindle), Stuffing Box
4)What are the types of control valves?
Globe control valve, Butterfly valves, Segmented V notch Ball Valves, Self-Actuated diaphragm valves, Eccentric Plug valves, Angle valve, 3-Way valves
5)What is meant by an actuator?
Makes the valve to operate through different energy inputs like Pneumatic, Electric Hydraulic etc..,
6)How does an actuator work?
Actuator make the valve spindle to move up and down depending upon the signal it receives from the positioner.
7)What are the types of actuators?
Pneumatic (Single acting /Double acting), Pneumatic Piston actuators, Electric Actuators, Hydraulic Actuators,rotary actuators
8)what is butterfly valve?
Butterfly valves are used only in systems where a small pressure drop across the valve is
allowed. The butterfly is fully open when the disc rotates by 90 degrees
9)What is a positioner?
Positioner is a component which make the valve to open or close to eliminate the process error and achieve the set point by generating input signals.
10)What is a quick exhaust valve?
Air quick exhaust valves are commonly used to allow rapid cylinder return without permitting air to travel back through the pneumatic system.
11)What is normally open? (In Point of Valves)
Often referred to as normally passing, air flows from the input port to the output port in the unactuated position.
12)What is normally closed? (In Point of Valves)
Often referred to as normally not passing, air flow is blocked at the input port in the unactuated position.
13)What is the function of a positioner?
Positioner measure the actual position of valve and take the command from controller, compare both the signals and make the valve to move either in open direction or close direction to correct the process error.
14)Where is an Air to close and Air to open control valves used ?
Reflux lines.
Cooling water lines.
Safety Relief services.
Feed lines
Steam Service.
15)What is a solenoid valve ?
A solenoid is electrically operated valve. It consist of a solenoid ( coil ) in which a magnetic
plunger moves which is connected to the plug and tends to open or close the valve.
16)What is the use of three way valves ?
Three way control valves are only used on special systems, where a dividing or mixture of
flows according to a controlled ratio is required.
17)why use 4-20 milliamps?
The 4-20mA signal is used over the 0-20mA signal, when the wire is broken or cut, it easy to detected with use 4-20mA signal. The current signal can be transmitted without error to a distance of 1000 meters
18)what are the parts of positioner?
spool, balancer, indicator.
19)types of positioners?
Conventional positioner
FF Positioner
20)how to identify the solenoid valve operation?
in Any solenoid is designated as X/Y way valve
Where,
X represents the number of ports
Y represents the number of positions