control valve selection

[alhnaity]

i have 3.8 bar line, which valve is better if the function is opening when pressure value in the line exceed 3.8 bar? pressure relief valve or pressure reducing valve or which type of control valves?

 

[mk3223]

What do it mean "the better for the function of opening"?
The valve type selection of these three valves, i.e. PSV, PRV, or CV, may be based on the requirement of the process design. And then, selection a valve with a proper opening function to meet the requirement.

 

[LittleInch]

Pressure relief valves tend to be spring operated and are inherently very reliable, both to open when you need and not open when you don't.

Other types of valve can be more precise and easier to vary the pressure at which they open or can work better if the amount of fluid they need to pass is very variable.

No data here so not easy to say much more.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[alhnaity]

The function is :Valve normally close if the pressure on the line is less than 3.8 bars.
If exceeds 3.8 bras valve will open partially or full up to the flow and the pressure.
Line pressure is measured by pressure transmitter fitted on the line, PT will send signal to DCS, and DCS send the analogue command to open and close the valve ( MOV), and drain the water to the tank.

 

[gerhardl]

Hello alhnaity,

To you, and all other presenting questions: Please have a look again at what LittleInch posts above:
Remember - More details = better answers

We now know that you handle water at a normal pressure of 3,8 bar, probably at a 10 bar (? ) normed system, and that you now operate and control by electrical signal and MOV valve. We do not know the quality of the water (pure or particles, chemical composition, temperature), flow, pipe-size and requirements (time and accuracy), consequences of failure and requirement for dependability..

Answer to your question:

1. Given a motor operated valve, it would be sensible to use an accurate and good quality control valve, 100% tight when closed, and with dimension for actual needed flow.

2. Alternative is an overpressure relief valve, operated by pilot system or spring, without and not dependable of electric signals and motor. For neutral water of drinking quality a pilot operated system will have the highest accuracy.

The rest is a full technical/economical evaluation case done by a qualified valve engineer.