Answer / bunny

Valve positioner is an instrument used with automatic
control valves,not with a manual valve.An automatic control
valve open/close basicaly according to the control signal
from a controler(e.g a PLC),say,4-20MA.For every control
signal comming from the controler,there would be a
corrsponding position for the valve plug,which determines
the flow rate.But in practical applications,the valve
position might not get maintained by the controller action
alone.So if there is any deviation in that position,we need
to rectify that and for that we are using a valve
positioner.

How to consider the flow directions for control valve (Globe) Is the there any easy understanding in order to select the flow directions?

3 Answers  

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why fuse block is not used for AI signal?

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3 Answers   Aramco, Reddy Labs,

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in instrumentation why we are using 4-20mA , why not voltage ? if somebody design a instrument which works on voltage then can we use that instrument?

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what is hall effect?where it is use in power plant?

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Give an example where you had aproblem on the job, and tell me how you solved the problem. and the finalvoutcome.

0 Answers   American Steel,

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how we calculate error in percentage when instrument calibrat

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what is IEC code in cables & how to selecting cables?

0 Answers   ROS,

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