Pilot Adjustment - Emerson ANDERSON GREENWOOD 93 Series Installation And Maintenance Instructions Manual

ANDERSON GREENWOOD SERIES 93 POSITIVE PRESSURE POSRV
INSTALLATION AND MAINTENANCE INSTRUCTIONS
PARTS LIST
Item Description
1 Cap
2 Pressure adj. bolt
3 Bonnet
4 Spring
5 Sense plate
6 Upper case
7 Spacer ring
8 Lower case
9 Boost spacer
10 Spindle diaphragm*
11 Seat/spindle*
12 Nozzle
14 Body
15 Vent
17 Check plate
18 Pilot diaphragm*
19 Boost plate
20 Sense spacer
21 Blowdown needle
22 Seal, body bolt*
23 Filter screen
26 Bonnet gasket*
28 Diaphragm gaskets*
29 Bushing seal*
30 Blowdown seal*
31 Spindle seal*
33 Shim washer
* Recommended spare parts for repair

4 PILOT ADJUSTMENT

4.1 General
Two adjustments are provided; one for varying
the pressure at which the pilot opens and
one for varying the pressure at which the
pilot closes. The first adjustment controls the
"set" or "popping" pressure, the second the
"reseat" or "blowdown" pressure. To adjust set
pressure, a test set-up similar to that shown in
Figure 5 should be used.
4.2 Set pressure
This adjustment is obtained by turning the
pressure adjusting bolt, clockwise (in) to
increase set pressure and counterclockwise
(out) to decrease set pressure.
4.3 Reseat pressure
This adjustment is obtained by turning
the blowdown needle adjusting screw,
clockwise (in) to increase blowdown,
counterclockwise (out) to decrease blowdown.
FIGURE 4
A
A small interaction between set pressure
and reseat pressure adjustments will occur,
therefore it may be necessary to readjust the
set pressure after setting reseat pressure.
Note: if the blowdown adjusting screw has been
moved or turned to either extreme, positioning
it midway will aid in obtaining the correct
blowdown. There are approximately 7 to 8 turns
to obtain full travel of the adjustment.
Midway from either end should produce a
blowdown for "snap action". For "modulating
pilot action", back the adjustment screw out
(counter-clockwise) to obtain the adjustment
limits given in paragraph 4.5.
4.4 Range of adjustment
All pilots can be adjusted + 10% beyond the
nameplate setting.
A
Medium pressure pilot
(above 15 psig)
View A-A
6