Honeywell MP-953D Installation And Maintenance Manual page 8

MP-953P PNEUMATIC OPERATORS USED ON ARMSTRONG HUMIDIFIERS
Feedback springs are available in a kit containing:
1 - Bronze feedback spring, operating range 5 psi
1 - Violet feedback spring, operating range 10 psi
To change the feedback spring:
3.
Turn off the instrument air.
Remove the pilot positioner by removing the two
remove the pneumatic tubing.
The feedback spring is located in the operator on
top of the main diaphragm.
feedback spring.
Insert the feedback spring that will give the
desired operating range.
located on top of the operator.
Replace the pilot positioner.
e)
Turn on the instrument air.
f)
ADJUSTMENT CHECK (MP-953B AND MP-953F MODELS ONLY)
1.
Install guages in the main and pilot air lines.
2. Main air pressure should be
of sequencing range:
for device to function.
3. Slowly apply pilot pressure and note the pressure at
which valve stem travel starts.
be within + 3/4 psi for the B model (+ 1 psi for the F
model) of the start point setting.
4. Slowly increase pilot pressure until valve stem travel
is complete.
for the B model (+lpsi for the F model) of the start
point pressure plus the range setting.
5 Make fine adjustments, if necessary, with the start
point adjustment knob.
the cover locking screws before turning the start point
adjustment knob.
equal
13 psi is minimum main pressure
This pressure should be within + 3/4 psi
CAUTION (B MODEL ONLY):
Remove the old
Replace the bias spring
to or more than top
This pressure should
Do not
Loosen