Answer / s vedpathak

Control valve is used in close loop control system.If it is
hunting , then to troublshoot first put loop for few sec in
manual mode, still if v/v is hunting then it is field
problem i.e v/v or I/P converter problem.

If it is not hunting in manual mode, then the problem can
be either the loop process variable(PV) is hunting or if PV
is ok, either the load/process is varied or loop needs
tuning.

Answer / kumar

1)I/P PROBLEM
2)INSTRUMENT AIR LEAK(Signal)
4)FLOW DISCHARGE FROM THE PUMP MAY FLUCTUATING.

Answer / mahesh kumar

Hunting Occur in theControl Valves due to inproper tuning
of PID loop, to remove thr hunting & for smooth operation
Tune the PID loop by adjusting the Gains

Answer / sam.r

An undesirable oscillation of appreciable magnitude,
prolonged after external stimuli disappear. hunting is the
evidence of operation at or near the stability limit.

in control valves is caused by the oscillation in the
loading pressure to the actuator caused by the instability
in the control system or the valve positioner .

Answer / sujitkumarnaik@indiatimes

if there is haunting in c/v that means there is disturbance
in i/p signal & o/p signal or feed back.so firstly calibate
it n observe.if still same prob. coming,adjust the pid tunning.

Answer / mostafa abo el-kasem

Several reasons can cause valve hunting; it can be from signal or from hard ware
To define:
1- Check controller o/p is stable while valve “you can put it in manual mode” is hunting or not (if not stable then it could be from the configuration or from PV change, you can check transmitter/damping/configuration,)
2- If signal is ok ,then it will be hardware problem from
a. Feedback arm not fixed
b. I/P problem
c. Diaphragm damage
d. Flow irregularities
e. Positioner tuning

Sir,I am going to sit for IOCL written test exam. recently.Can anyone tell me the name of 'Objective type Question Book on Instrumentation Engineering ' which will help me. Pl. mail to bidyut_71@rediffmail.com / bidyut.saha2008@indiatimes.com / bidyut.saha09@yahoo.in

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