control valve calibration

Refer Vendor Manual .

Hi there,

Look through the forum and you will find various references to control valves.

If you do not know how to calibrate a control valve - then I doubt that you know how a control valve works.

Your first stop should be to download the Fischer control valve handbook. It is free and you can get it from the Emmerson website.

Read it and understand it. Then take your questions to your control valve supplier, hopefully they can give you a demonstration.

To try and explain this would open a can of worms as you would need to be familiar with the technical terms associated with valves.

Regards,

Craig

HI Craig,

I am as Instrument Trainer, could you give me the simulation or graphic for control valve calibration an also valve assembly.

Regards,

amizi

www.emersonprocess.com

Do to documentation, then go to Fischer control valves, then download the cotntrol valve handbook.

Regards,

Craig

Control valves don't measure anything, so they can't be "calibrated".

They can be set up, though. The usual method, though not always, is to set them up so that 0-100% of the input signal range is mapped to 0-100% of the opening range.

Control valves differ in their design. The best bet is to refer to the manufacturer's information supplied with the valve. The works Instrument Workshop will have a copy, or failing that, a written procedure for its technicians to follow. Have a chat with the workshop Supervisor, perhaps? How about a few days' practical training in the workshop itself?

pettannu padichittu paranju tha keto

????

since the topic is control valve calibration, i want to ask a question.

In my plant Usually when the valve is suspected to be passing or problematic, first thing is instrument group will be called in to check and calibrate the valve.

Standard calibration will check for 4-20mA and the corresponding of valve openiong 0-100%.

But still at times mechanical group will not trust the calibration especially of 0% closing. They will insists of doing "manual turning" the actuator till the plug reaches the seat satisfactorily. Is this procedure correct?

Hi there,

Your instrument department should have made sure that the valve was seating correctly in the first place. So I don't see any problem with the mechanical people making sure that the valve is seating.

Cheers

Craig

Hi,

How to make sure of that if you cannot see the plug and seat inside the casing?

The best is to make sure 0% correspond to 4mA output.

Hi there,

You do not need to to see the plug or the seat. You can feel on the valve stem when the valve has seated. You cannot however be sure about leakage unless you do a leak test.

Cheers

Craig