Stem Seal Replacement Kit for Types PF5 and PF6 Piston Actuated Valves

3733250/1
IM-P373-15
CH Issue 1
Stem Seal Replacement Kit
for Types PF5 and PF6 Piston Actuated Valves
Installation and Maintenance Instructions
1.0 General safety information
This document should be read alongside the Installation and Maintenance Instructions
(IM-P373-05) supplied with the original product, and should be treated as a supplement
sheet to the afore mentioned.
Fig. 1 Stem seal replacement kit for type PF51 Type 2 and Type 3 actuators
2.0 Stem seal replacement:
- Isolate the upstream and downstream valves.
- Vent the pilot pressure from the actuator and disconnect the pilot pipework / solenoid valve.
- Remove the piston actuated valve from the pipeline.
- Remove the valve body. Caution: Before removing the valve body on normally closed valves,
the spring pressure acting down onto the valve head seal should be relaxed to prevent
damage. This can be carried out in one of two ways:
1. Undo the actuator cover to relax the spring force while retaining the valve body and then
remove the actuator and valve stem.
2. Apply air pressure at the inlet port of the actuator, which will compress the spring and
remove the downward force, then remove the actuator and valve stem.
Printed
IM-P373-15
in the CH
UK Issue 1
© Copyright 2005
-
To replace the main stem seals, remove the actuator housing cover whilst holding the valve
body firmly. Warning: The internal spring is under compression. Remove the valve body.
Whilst holding the valve head securely, unscrew the red travel indicator and stem lock-nut then
remove complete with the two washers.
Remove the piston, stem '0' ring and washer along with the spring and valve stem.
Remove the piston housing securing nut, whilst holding the bonnet in a secure position.
Replace as required the stem sealing kit.
Clean out any dirt or waste deposits from inside the piston housing area and carefully apply
Viton compatible inert grease to the '0' ring and piston lip seal.
Reassemble in reverse order referring to the drawings showing correct location of components,
see Figure 4 and torque settings (page 10 of IM-P373-05).
Fig. 2
Stem seal kit for
Types PF5 and PF6
piston actuated valves with
Type 1 actuator
(INC-BD-NO)
2
Fig. 3
Stem seal kit for
Type PF6
piston actuated valves with
Types 2 and 3 actuator
(2NC-NO-BD and 3NC-NO-BD) Stainless steel only
IM-P373-15 CH Issue 1
NC (Normally Closed) valves
Red travel indicator
Spring washer
Stem lock-nut
Spring
Washer
Piston
Piston lip seal
Stem 'O' ring
Piston
Washer
Valve stem
NO (Normally Open) valves
Red travel indicator
Washer
Stem lock-nut
Piston
Spring washer
Stem 'O' ring
Piston lip seal
Washer
Spring
Valve stem
BD (Bi-Directional normally closed) valves
Valve stem
Valve head seal (PTFE)
Type PF6_G
Type PF51G
Body seal
Body 'O' ring
Body seal
Valve body
Valve body
Retaining cap nut
Fig. 4
IM-P373-15 CH Issue 1
3
4
IM-P373-15 CH Issue 1
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