172-65587MA-02 (CV-COSR Pneumatic Control Valve) 3 Jun 2019
13
Adjusting the Zero/Span
1. After connecting the air piping, operate the air pressure reducing valve to maintain
the positioner air supply pressure at 0.38 MPaG (54 psig) (reverse action).
2. Connect a current generator or a controller for input of an operation signal of 4 to
20 mA.
3. Loosen the cover plate screw and open the cover plate.
4. Pull out the jumper pin. (Be sure not to lose it.)
5. Set the operation signal output from the current generator or controller to 4 mA
(0%).
6. Turn the zero adjustment dial slowly until the valve just begins to open (the
actuator pressure gauge just beings to move). (The valve must NOT be open.)
NOTE: Turning counterclockwise causes the valve to begin to open earlier.
7. Change the operation signal to 4.1 mA (1%) and check to make sure the valve
begins to open.
8. Change the operation signal to 4 mA (0%) and check to make sure the valve is
completely closed (the actuator pressure gauge is completely at zero).
9. Change the operation signal to 20 mA (100%), and make sure that the stroke
indicator reads in the vicinity of 100%.
If it does not, use a precision flat-head screwdriver to turn the span adjustment
potentiometer until it is close to 100%.
NOTE: Turning clockwise increases the stroke (travel).
10. Each modification of the span results in a zero shift. Repeat the above correction
procedure until both the zero and span are correct.
11. After completing the adjustment, insert the jumper pin securely into their previous
position and close the cover.
Stroke Guide
Zero/Span Adjustment
100%
50%
0%
Stroke Gauge
Span Adjustment
Potentiometer
Jumper Pin
Cover Plate
Zero Adjustment
Dial
