Adjusting The Proportional Band Xp And Air Delivery Q - Samson 3767 Mounting And Operating Instructions

100%
Open
Travel
Closed
0%
Fig. 13: Normal or split-range operation
5.1.1 Adjusting the proportional
band Xp and air delivery
Q
1. Close the volume restriction (11) as far
as the required positioning speed
permits.
Check the positioning speed by pushing
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 proportion-
al band X to a value half way (half
p
turn).
5. Check the valve's tendency to hunt and
the positioning speed by briefly tapping
the diaphragm lever (3).
The X value is to be adjusted to be as
p
small as possible, without considerable
overshooting occurring.
EB 8355-2 EN
< > < <
4
20 mA
Reference variable
Input signal
100%
< >
Open
Travel
Closed
Valve 2
0%
4
Dead band
NOTICE
Always adjust the X
fore setting the starting point.
Changing it later will cause the zero
point to be shifted.
Operation
< <
Valve 1
12 20 mA
restriction be-
p
39