4.1.1 Adjusting the proportional
band Xp and air delivery Q
1. Close the volume restriction Q (11) as
far as the required positioning speed
permits.
To check, push the diaphragm lever (3)
as far it will go.
2. Adjust the reference variable at the input
to approx. 50 % of its range.
3. Turn the zero adjuster (6.2) until the
valve has reached approx. mid-travel.
4. Use the adjuster (8) to set the propor
-
tional band Xp to a medium value (½
turn).
5. Check the valve's tendency to hunt and
the positioning speed by briefly tapping
the diaphragm lever (3).
The Xp value is to be adjusted to be as
small as possible, without considerable
overshooting occurring.
Note: Always adjust the Xp restriction be-
fore setting the starting point.
Later modifications shift the zero point!
4.1.2 Settings for actuator:
"Actuator stem extends"
NOTICE
To ensure that the valve can be closed with
full force, fully vent the diaphragm chamber
when the reference variable reaches its
lower (operating direction <<) and upper
(operating direction <>) value.
As a result, adjust the input signal to a
slightly increased starting point of 0.23 bar
for direct operating direction <<; for reverse
operating direction <>, adjust the input sig
-
nal to a slightly reduced starting point of
0.97 bar.
Starting point (e.g. 0.23 bar)
1. Use the pressure adjuster to set the input
signal to 0.2 bar.
2. Turn the zero adjuster (6.2) until the
valve just starts to move from its initial
position.
3. Shut off the input signal and slowly in-
crease it again. Check whether the valve
starts to move at exactly 0.23 bar.
Correct any deviation at the zero ad
-
juster (6.2).
Upper range value (e.g. 1 bar)
1. Once the starting point has been set, in
-
crease the input signal to 1 bar using the
pressure adjuster.
At exactly 1 bar, the plug stem must stand
still, having passed through 100 % travel
(watch the travel indicator at the valve).
EB 8355-1 EN 33
Operation
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