Answer / goutam chatterjee

first of all we cant say any valve as a control valve with
out positioner... because we know that control valve is a
final control element.. we only say any valve as a control
valve when its acted as percentage operation as per process
requirement. with out positioner this is acted as a simple
on off valve... because percentage opening not possible with
out positioner... & we need to calibration the positioner
because cv alwys maintain the process in aspect of its final
contron ability.... i.e if process need to open the cv 25%
if the positioner not calibrated then it may be open 30 or
10 % for example... thats why we need to calibrate the
positioner.....

Answer / ghanshyam khatri

yes u can use without positioner,potioner is used for quiq
operation not for control cv is control through 0.2 to 1.0
kg/cm2 u can give it directly but u need to adjust bench
set spring pressure is .2 to 1kg.

Answer / senthil r.m

my dear,
when there is no positioner it is not called as control valve.i think u dont know about it.we will give 4 to 20 milliamps to the positioner accordin to tht the valve throttles b/w 0 to 100%.Tuning is different concept which i can give u details to go through it.senthilrmohan@gmail.com

Answer / inst engg

YES, BUT IT IS NOT PERMANENT REMOVE THE MAIL LINE (FORM THE
POSITIONER)TO THE CV AND GIVE THE SUPPLY PRESSURE.
TUNNING IS REQUIRED FOR EXACT PERFORMANCE(Eg. YOUR CV HAVING
2% ERROR ,YOUR CONTROLLER IS GIVING 23% CLOSE BUT YOUR CV
WILL CLOSE 25% IT WILL AFFECT THE PROCESS) AND PERFECT
SEATING OF GATE.

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