4.5
Model 20 HT Valve
4.5.1
M20HT Description
This section presents information to disassemble, clean, and rebuild the Model 20 High
Temperature (Model 20 HT) Valve. The Model 20 HT Valve is similar to the standard Model
20 with a few distinct differences. Procedures to disassemble and clean the Model 20 HT are
very similar to the Model 20. However, procedures to re-assemble the Model 20 HT valve are
different from the standard Model 20.
Like the standard Model 20 valve, maintenance procedures for the Model 20 HT valve are
grouped into two types, Mini-Maintenance procedures and Maxi-Maintenance procedures.
Mini-Maintenance procedures involve working on the valve while it is still installed in the
analyzer. Maxi-Maintenance procedures may be used when Mini-Maintenance does not
correct a valve fault. This manual covers the Maxi-Maintenance procedures in the following
order.
● Valve Cap Disassembly
● Actuator Disassembly
● Cleaning Actuator, Fittings, Tubing, etc.
● Actuator Assembly
● Valve Cap Cleaning and Assembly
To assure optimum valve operation, a clean contaminant free work environment is required
for this procedure. To repair the valve on site, the customer must have the necessary
maintenance tools and replacement parts. Recommended valve spare parts can be obtained
from Siemens. Recommended tools will include an ultrasonic cleaner and a clean workstation
with lint-free cloth.
Mini-Maintenance procedures can be found in the Maxum II Maintenance Manual. This manual
can be found on the Maxum II Documentation CD (part number 2000597-001). Additional
procedures related to the Model 20 High Temperature Valve can be found in the Model 20
High Temperature Valve Repair Manual, which can also be found on the Maxum II
Documentation CD.
It may be easier and less expensive to replace a valve or return it to Siemens for service rather
than perform Maxi-Maintenance.
4.5.2
M20HT Intended Users
This procedure is intended for qualified users with sufficient training to safely repair a valve in
the field. If customer maintenance personnel are not technically trained to repair the valve on
site, it is recommended that the valve be returned to Siemens for repair or direct replacement.
In addition to training, the customer must have a clean work environment available for
rebuilding and cleaning the valve. Performing the work in a contaminated environment, or
performing the work incorrectly may damage the valve.
Valves
4.5 Model 20 HT Valve
Maxum II Valves and Oven Components
68
Service Manual, 10/2018, A5E42019844001
