Spirax Sarco PN9100, PN9200, and PN9300 series pneumatic actuators utilize a dedicated stem seal kit (positions 17, 18, and 30) to ensure reliable operation and prevent leakage along the actuator spindle. This kit is a critical maintenance component designed specifically for these actuator models and is common for both spring-extend and spring-retract versions.

Kit Contents and Materials

The stem seal kit comprises three specific components designed to provide low-friction movement and robust sealing for the actuator spindle.

Position No.	Part	Material
17	Bearing	PTFE/steel composite
18	Seal	Polyurethane (FKM for T version)
30	Gasket	Reinforced graphite

How to Replace the Stem Seal

Safety Information

Before commencing any work please refer to the Safety Information - Maintenance section of the actuator manual. Ensure the control valve has been isolated and the actuator housing is pressure free.

1. Remove the diaphragm from the actuator as described in the diaphragm kit replacement instructions (Section 5.3.1 for Extend version and 5.4.1 for Retract version).
2. Before refitting the diaphragm (4), remove the stem (6) from the housing.
3. Remove and safely dispose of the stem seal (17) and stem bearing (18) in line with local regulations.
4. Refit the new stem seal (17) and stem bearing (18).
5. Refit the stem (6) into the stem seal (17) and bearing (18).
6. Proceed to diaphragm refit as described in the diaphragm kit replacement instructions.

Ordering Information

Always order spares by using the description given in the available spares list and state the actuator model.

Example: 1 - Stem seal kit for a PN9120 pneumatic actuator.