MAINTENANCE
Series 655
84/112
Edition 23.09.2019
979645EA
7.2
Maintenance procedures
•
Replacement of isolation seal (plate seal) and valve cleaning. Refer to chapter: «Replacement of
isolation seals and cleaning».
•
Replacement of plate complete. Refer to chapter: «Replacement of plate complete»
•
Replacement of actuator and actuator shaft seals. Refer to chapter: «Replacement of actuator and
actuator shaft seals».
•
Required frequency of cleaning and replacement of seals is depending on process
conditions.
•
A critical factor influencing the maintenance period is the lifetime of the vacuum
grease, being limited under increased temperature. In this case grease will
separate to PTFE and oil. The oil may flow and contaminate the valve parts.
VAT can give the following recommendations for preventive maintenance:
Replacement of
unheated
1)
heated
≤
80 °C
1)
heated > 80 °C
1)
isolation seals (plate seal)
75’000 cycles but
12 month (or
earlier depending
on process)
6 months but
max. 75’000 cycles (or
earlier depending on
process)
3 months but
max. 75’000 cycles (or
earlier depending on
process)
actuator shaft seals
2’000’000 cycles
6 months
3 months
