Answer / ravi sankar

we can calibrate the control valve by using source meter
which is used to give 4 to 20 ma source to I/P , if any
error in the I/P ,we can adjust the zero or span of I/P.if
any error in the valve position ,adjust the zero or span in
the posisner of the control valve.

Answer / aby

If the signal is directly connected to EP then we can use
source meter and adjusting the zero and span by giving 4
and 20 mA. If there is I/P then also this method is
applicable. Now if the pneumatic signal to the positioner
is in standard form and not working properly then we can
adjust the valve positioner for proper working..

Answer / v.suresh kumar instrumentation

The calibrate the control valve used for mA Source
Meter .mA Souce apply for I/P Converter so Opening Closed
for Control Valve .At the opening closed time measured for
position note.Supposed opening for Valve positioner 50% ma
13.5 So adjust the Zero or Span Calibration to Control the
ositioner
Chart
% Actual Value Error Zero/Span
0 4.7mA 0.7 4mA
25 8.5mA 0.5 8mA
50 12.0mA 0.0 12mA
75 16.4mA 0.4 16mA
100 20.5mA 0.5 20mA

Answer / shan

It is simply by using a source meter or loop calibrator.
Inject 4-20mA to the current-pneumatic converter and check
the response of the valve. If you notice that an error
occurs,you can adjust zero or span at the control
positioner...

Answer / chek mohidein

For the calibration of a control valve a loop calibrator or
a pressure calibrator can be used between 3-15psi.Check the
valve position for 3psi which is to be 0 for a NC type
valves.In such manner check the valve positon for various
ranges(6psi,9psi,12psi & 15psi).the valve positon shoul be
0 for 3psi and 50% for 9 psi and completely opened for
15psi.
The same procedure is applicable for NO type valves.The
valve is open for 3 psi and completely closed for 15psi.
Any errors occured may be rectified by Zero span adjustment.

Answer / bill

pneumatic calibrator

Answer / veerababu

ma FEEDER IS USED FOR CALIBRATING THE CONTROL VALVE AND
GENERALLY WE ARE ADJUSTING VALVE POSITION 0%,25%,50%,75%
and 100%AT 4,8,12,16 and 20ma.

Answer / nawras

by force 4-20ma from vontrol valve and see what the responce
that meaning 4ma for 0
8ma for 25%
12ma for 50%
16ma for 75%
20ma for 100%

Answer / ezhil

standard air pressure regulator is used.
air is supplied to positioner and the movement of
the actuator is noticed and adjusted. 0.2 and 1 kg/sq. Cm of
pressure is applied for zero and span adjustment

Answer / mat

This is control valve calibration not transmitter, for control vale calibration we have to used pneumatic source from this source we can give pressure from 3psi to 15 psi.

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