PRX Series
6
3. Use a wrench to hold the stem (key 23) and break loose
the stem nut (key 20). Remove the stem nut and washer
(key 11).
4. Remove the upper diaphragm plate (key 13), diaphragm
(key 14), pad holder (key 22) and O-ring (key 18).
Inspect parts for damage or wear, replace if necessary.
5. Remove orifice (key 19) and O-ring (key 17). Inspect
the parts for damage or wear and replace if necessary.
Lightly lubricate the O-ring and place in the body
(key 16). Install the orifice.
6. Set the pad holder (key 22) in the body (key 16).
7. Lightly lubricate the rims of the diaphragm (key 14) and
place it on top of the pad holder (key 22). Set the upper
diaphragm plate (key 13) on the diaphragm (key 14).
8. Lightly lubricate the O-ring (key 18) and place it in the
lower case (key 21).
9. Place the washer key (key 11) and stem nut (key 20) on
the stem (key 23) and tighten.
If also performing Upper
Case Maintenance, skip to step 2 of the Upper Case
Maintenance section.
10. Insert washers (key 11) and machine screws (key 10) in
the lower cover (key 21) and tighten uniformly to ensure
proper seal.
Upper Case Maintenance
1. Disconnect pilot and remove it from the line.
2. Loosen locknut (key 2) and back out adjusting screw
(key 1) until compression is removed from the spring.
Remove cap (key 3).
3. Lift the upper spring seat (key 6), spring (key 7) and O-ring
(key 4) out of the upper cover (key 8). Inspect O-ring and
replace if necessary.
4. Remove machine screws (key 10) and washers (key 11)
from lower cover (key 21) and the separate lower cover
from the body (key 16), unless removed during lower
diaphragm maintenance. Use a wrench to hold stem
(key 23) securely while removing the stem nut (key 26).
5. Remove remaining loose components: washer, upper
diaphragm plate, diaphragm, lower diaphragm plate
and O-rings (keys 11, 13, 14, 15, 18 and 25). Inspect
diaphragm and O-rings for damage or wear and replace
if necessary.
6. Lightly lubricate the O-ring (key 25). Place O-ring over the
stem (key 23) and press it down into the body (key 16).
7. Set the lower diaphragm plate (key 15) into the body
(key 16).
8. Lightly lubricate the rims of the diaphragm (key 14) and
place it in the body (key 16) on top of the lower diaphragm
plate (key 15).
9. Set the upper diaphragm plate (key 13) on top of the
diaphragm (key 14).
10. Place washer (key 11) and stem nut (key 26) on the stem
(key 23) and tighten using a wrench to hold the stem.
11. Place the lower spring seat (key 9) on the upper
diaphragm nut (key 26) and mount the upper cover
(key 8) on top of the body (key 24) and the diaphragm
(key 14).
12. Place washers (key 11) and uniformly tighten the
machine screws (key 10) to hold the body (key 24) and
upper cover (key 8) together. Position the diaphragm
convolution facing down and make sure that the
diaphragm is not deformed and is properly installed.
13. Install spring (key 7) and upper spring seat (key 6) on
top of the lower spring seat (key 9) inside the upper
cover (key 8). Install cap (key 3).
14. Screw in adjusting screw (key 1) at desired spring
compression and use the lock nut (key 2) to lock the
adjusting screw’s position. Refer to Pilot Adjustment
section (pages 5 and 6) to adjust pilot settings.
Damper and Restrictor Maintenance
1. Remove screw (key 31) and plate (key 29).
2. Remove ring nuts (key 30).
3. Remove damper adjusting screw (key 27). Remove and
inspect O-ring (key 28) for damage or wear and replace if
necessary. Lightly lubricate O-ring before placing on the
adjusting screw. Insert damper adjusting screw into the
body (key 16) and tighten. Insert ring nut (key 30) and
tighten. Back out damper adjusting screw until it stops.
Note
When using a Type PRX/120 pilot with a
Type PRX/125 pilot as a monitor, use the
following settings:
• Restrictor – completely tighten and then
back out three full turns.
• Damper – back out until it stops.
4. Remove restrictor adjusting screw with hole (key 32).
Remove and inspect O-ring (key 28) for damage or wear
and replace if necessary. Lightly lubricate O-ring before
placing on the adjusting screw. Insert restrictor adjusting
screw into the body (key 16) and completely tighten.
Insert ring nut (key 30) and completely tighten. Back out
restrictor adjusting screw 1/2 turn.
5. Install plate (key 29) and screw (key 31).
The Types PRX/131 and PRX/182
Maintenance (Figures 3 and 4)
CAUTION
Always remove spring (key 7) tension before
performing maintenance on this unit. To
remove spring tension, loosen locknut (key 2)
and back out adjusting screw (key 1) until
compression is removed from the spring.
