Siemens Maxum II PD PA AP Service Manual page 49

6. Make note of the valve orientation in the oven.
7. To remove Model 50 valve from the oven, first disconnect all tubing to the valve.
Note
When disconnecting Valco fastening nuts from Model 50 valve, exercise caution not to bend
or crimp the stainless steel tubing.
Note
Before removing Model 50 valve from oven, make note of its orientation within the oven.
8. Remove the valve from the oven by unscrewing the two M3 x 35 socket head cap screws
securing the Model 50 valve. These mounting screws are located between ports 2 and 3
and ports 8 and 9. Refer to Figure 6-2 for port locations.
Note
If the valve is to be sent back to Siemens for service, then skip to the "Valve Reinstallation"
portion of this procedure to install the replacement valve.
Valve Disassembly, Cleaning, and Reassembly
1. Place the valve on a clean dust lint free cloth within a clean work environment.
Note
Do not place polished top plate, center plate or bottom plate against any abrasive surface.
Place components on a lint free cloth free of foreign contaminants.
2. Place the valve bottom plate on a lint free cloth. Using a 2.5 mm Allen wrench, remove the
five socket head fastening cap screws.
3. Separate Top, Center and Bottom plates of the valve, placing them on a lint free cloth.
Both diaphragms are visible.
4. Remove the old diaphragms from the plates. DO NOT attempt to reuse the old diaphragms.
5. Clean the valve parts by wiping with a dust/lint free cloth and a cleaning solvent (or clean
using an ultrasonic cleaner) as described at the beginning of this chapter. After cleaning,
shake excess cleaning fluid from all parts and allow to air dry before reassembling.
6. With the pins installed in the base of the assembly fixture, place the bottom plate of the
valve on the center of the base. The pins should fit in the mounting holes on the bottom
plate and hold it in place.
Note
Use the Valve Assembly Fixture, Siemens Part Number 2020281-001, to properly align the
diaphragms when rebuilding the Model 50 valve. The fixture consists of a base, two guide
pins, and a diaphragm placement disc. This fixture will allow the user to place the diaphragm
in the center of the valve. If the diaphragm is not in the center, it may leak.
7. Position the placement disc on the bottom plate and set the diaphragm in place.
Maxum II Valves and Oven Components
Service Manual, 10/2018, A5E42019844001
Valves
4.3 Model 50 Valve
49