Figure 4-20 Assembling Bal-Seal (13) On Piston (15) - Siemens Maxum II PD PA AP Service Manual

Valves
4.5 Model 20 HT Valve
5. Apply a bead of Krytox 240 AC lubricant, or equivalent, in both Bal-Seal grooves of air-
loaded piston (18).
Figure 4-20 Assembling Bal-Seal (13) on Piston (15)
6. Using the pads of your fingers (or an "O" ring as a cushion), install the small spring loaded
Bal-Seal (20) in air loaded piston (18) groove with associated spring facing up. DO NOT
use a fingernail. Refer to Figure 6-5.
7. Push spring loaded Bal-Seal (20) to the bottom of groove.
8. Apply small bead of Krytox 240 AC lubricant, or equivalent, on the small Bal-Seal sealing
surface of lower spring loaded piston (15).
9. Place upper air loaded piston (18) over the small diameter of lower piston (25). Position
pistons using guide pin for proper orientation.
10.Screw the assembly stud and washer into the threaded hole in the lower spring loaded
piston (15) and evenly force the spring loaded Bal-Seal (20) over the bearing surface of
lower spring loaded piston (15). Leave the assembly stud and washer in place.
11.Moderately lubricate outsides of Bal-Seals with Krytox 240 AC lubricant, or equivalent. Also
lubricate each of the six fingers of spring. This is where fingers contact plunger valve body
(17).
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Maxum II Valves and Oven Components
Service Manual, 10/2018, A5E42019844001