M20Ht Procedure - Actuator Disassembly - Siemens Maxum II PD PA AP Service Manual

Valves
4.5 Model 20 HT Valve
4. Inspect the Teflon seal disc diaphragm (33) and the Nomex cushion diaphragm (34).
Examine valve cap base seal (33) and cushion diaphragm (34) subassemblies for dirt,
contamination or breaks.
Regardless of whether damage or contamination is evident, discard old seal and cushion,
and replace them with new component(s).
5. Visually inspect the rest of valve. If it is clean and in good condition, install a new disc seal
diaphragm (33) and cushion diaphragm (34).
To reassemble the valve cap, refer to the applicable steps later in this chapter.
Note
The valve cap and fittings will be cleaned before reassembly. This step will be executed
later in this chapter.
4.5.9

M20HT Procedure - Actuator Disassembly

Note
In the next three steps, valve plungers (14) are checked for sticking.
1. Using even finger pressure around edges of plunger valve body (17), push valve plunger
body against cylinder valve base (16). All six plungers should rise.
2. Release plunger valve body (17). The six plungers should drop. If plungers do not drop,
check for oil film on plungers. This can prevent plungers from dropping.
3. Apply gentle pressure to the top of each of the six plungers. If plungers drop, without
excessive pressure, the valve is operating normally and does not require additional
disassembly. If plungers stick or are sluggish in their operation, they must either be
thoroughly cleaned with a recommended cleaning solution, repaired, or the entire actuator
must be replaced.
4. Remove all connections from the valve and remove the entire valve from the oven. While
removing the valve, hold it upright to prevent plungers from falling out.
Additional work should be on a clean workspace.
5. Turn the actuator on its side. Remove the three socket head screws (35) which secure the
plunger valve body (17) to the cylinder valve base (16).
Note
When performing the following step, DO NOT allow actuator plungers to fall from plunger
valve body (17).
6. With plunger valve body (17) in the horizontal position, remove the assembly. Carefully
remove all six plungers (14).
Note
Perform EITHER step 7 or step 8 to remove the actuator piston from the cylinder base.
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Maxum II Valves and Oven Components
Service Manual, 10/2018, A5E42019844001