7. Place cylinder valve base (16) in upright position. Insert a 6-32 hex threaded standoff screw
into the center-threaded hole and pull to remove air loaded piston (18) and spring-loaded
piston (15).
Note
In the following step, DO NOT use more than 30 psig (210 kPa) of air pressure when using
this method.
8.
Alternate method for removing actuator piston.
Carefully apply 10 psig (70 kPa) of air pressure on bottom port of cylinder valve base (16).
This extends the pistons allowing them to be pulled out of cylinder valve base by hand.
9. Inspect actuator cylinder walls and the three Belleville washers (19). These components
must be clean and show no evidence of damage. If necessary, clean parts or replace them.
10.Separate the upper air loaded piston (18) and lower spring loaded piston (15). Inspect
pistons and spring loaded Bal-Seal (20) and Belleville washer (19). These components
must be clean and show no evidence of damage. If necessary clean parts or replace them.
4.5.10
M20HT Procedure - Actuator Re-assembly
Note
It is extremely important that, when reassembling the actuator, that the assembly area be clean
and dust free. Hands of maintenance personnel must be clean and not oily and tools must also
be clean.
Note
Be certain valve cap (32) does not rest on abrasive surface and valve cap has completely air
dried before reassembly. Rest valve cap on a clean lint free cloth.
1. Install the three large Belleville washers (19) in cylinder valve base (16). Washers must be
positioned in an alternating bevel up, bevel down manner (to form a spring). Refer to Figures
6-2 and 6-3.
2. Apply a bead of Krytox 240 AC lubricant, or equivalent, in Bal-Seal grooves of spring loaded
piston (15).
3. Lubricate outside diameter of assembly tool (Part Number A00145). Be certain spring-
loaded Bal-Seal (13) is properly oriented with the associated spring facing up.
4. Using an "O" ring as a cushion, push spring loaded Bal-Seal (13) down on the assembly
tool until it snaps firmly into spring loaded piston (15) ring groove. Refer to Figure 6-4 on
the next page.
NOTICE
When installing Bal-Seals, handle them with extreme care. Do not remove Bal-Seal
springs for installation and do not nick or scratch Bal-Seals.
Valves
4.5 Model 20 HT Valve
Maxum II Valves and Oven Components
Service Manual, 10/2018, A5E42019844001
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