Instrumentation Interview Question:

Can we use a control valve without positioner?

Submitted by: Administrator

Control valve can not be without positioner. The purpose of the positioner is to control the control valve stroke so as to keep the valve in desired position. The positioner receives signal from the controller, and send the boosted signal to the actuator to reach the desired position as and when the valve reaches the desired position the positioner cuts the boosted signal to the actuator and keeps the position.
Submitted by: Administrator

yes, we can use control valve without a positioner, in fact when the positioner is malfunctioning there is a provision to bypass it until possible to repair / replace, however we cannot get efficient control valve operation without positioner, so ideally positioner should be installed for control valves.
Submitted by: Mahesh Tulsiani

Yes,we can use a control valve without a positioner.But when there is a deviation of the valve plug from the desired position decided by the controller due to some external disturbances,it cannot be rectified without a positioner.So its better to use a valve with a positioner.
Submitted by: Vivek Narayanan

As per control application and process design/requirment still many pneumatic control loops available without positoner control valve. so my answer is yes.
Submitted by: Amjad Ali

Yes but we are not control same like on off valve.
Submitted by: Deenathayalan

If control valve bench set is 0.2 kg/cm2 to 1 kg/cm2 then we can use a control valve without positioner.
Submitted by: Naveed Ahmad

Yes, we can.
By connecting the electrical controller output signal (4-20mA) to an I/P and connecting the I/P output signal (3-15psi) to the control valve diaphragm you can control the control valve.
You can also actuate the control valve by the output signal of a pneumatic controller directly.
The point is you are going to have an open loop control.
Submitted by: Adel Ahlenajafi

Yes We Use Controle Without Positioner. In that case We use I/p Converter and Then we use pnuematic signal 3 to 15 Psi at in put and for signal regulation we use pnumetic controler. And we achieve our desire position.
Submitted by: Muhammad Farooq Abdullah