Reversing a positioners action
A common question that Valve Accessories & Controls often gets from the field is that a customer
has a valve package with our positioner however they wish to reverse the input signal and action
of the valve. For example a customer has a valve that is closed at 4mA and open at 20mA. The
below diagrams are 4mA closed and 20mA open. The diagram on the left is a double acting
actuator and the one on the right is single acting.
The customer would now like the opposite from their valve. They would like to have open at
4mA and closed at 20mA. The diagrams below are 4mA open and 20mA closed. The double
acting is on the left and single acting is on the right.
Here is a step by step procedure in getting from 4mA closed and 20mA open to 4mA open and
20mA closed.
For the positioner adjustment, we have to make two key changes:
1-change the actuator/positioner porting
2-change the cam configuration
