If a control valve is hunting means means if we are giving 50% to the cv, the

If a control valve is hunting means means if we are giving
50% to the cv, the cv will open at 51% then slowly slwoly
it will reaches 49% , then it will reaches again 50%, this
type of action occured frequntly.. so what to do for solve
this problem. The possible cause is in volume booster or
positioner's relay.. positioner is double acting .. and
make siemens..sipart.The cv is double acting and mounted
for anti surge operation, it having 4 nos. volume booster,
one sov, one positioner, etc..?

Question Posted / mksonipadra

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Gujarat Fluorochemicals Limited (GFL), Shell, I also Faced
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If a control valve is hunting means means if we are giving 50% to the cv, the cv will open at 51% ..

Answer / aftab ahmed mazari

Check the following items:
1. Any loose connection or leakage of pneumatic signal.
Check all tube fittings with soap solution.
2.Check the gland packing should not be so tight. If feel
tight, get loose them a bit.
3. Check the pneumatic relays of Postioner. Get clean its
ports, nozzle, flapper etc.
4. Also check, that linkage, feed back mechanical link
should not have any dent, grove, burs etc.
aftabmazari@yahoo.com

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If a control valve is hunting means means if we are giving 50% to the cv, the cv will open at 51% ..

Answer / avinash d. pagar

Also please check volume booster function separately with
out positioner and then set factory setting of positioner.
again calibrate positioner by auto calibration. mostly
hunting and over shooting issues cause by booster error.

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