Emerson Daniel 788DVC, User Manual

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Table 9-2: Valve cylinder head to cylinder (socket head screws) torque specifications
(continued)
NPS Class Socket head screw
size Torque (ft-lb)
4 150 1/4"-20 5
4 300 1/4"-20 5
6 150 1/4"-20 5
6 300 1/4"-20 5
8 150 5/16"-18 11
8 300 5/16"-18 11
9.4.2 Standard cylinder reassembly
Reassembly of a control valve without a position indicator
Procedure
1. Place the cylinder in an upright position with the ports on the bottom. Lubricate the
inside of the cylinder wall with a suitable lubricant.
2. Insert the O-ring into the groove inside the bottom of the cylinder. This will require
some effort.
3. Insert the seat ring into the cylinder; placing it on top of the O-ring.
4. Using the piston as your tool, place it nose end down into the cylinder on top of the
seat ring. Using a hammer handle or similar device, press down on the piston to
force the seat ring into position against the lip in the cylinder.
5. Remove the piston from the cylinder.
6. With the piston in a vertical position, nose end down, place the O-ring into the
groove on the piston. (If the valve is a high-pressure model, the piston will require
PTFE backup rings on either side of the O-ring.
7. Place the indicator stem retaining ring into the counter bore of the piston. Place the
washer on top of the indicator stem retaining ring. Using retaining ring pliers, place
the retaining ring on top of the washer.
8. Insert the piston into the cylinder, nose end down.
9. Insert the spring into the piston.
10. Turn the jack-out screws in the cylinder head to their original position.
11. Place the O-ring into the groove in the cylinder head.
12. Place the cylinder head on top of the spring, and use an arbor press against the top
of the cylinder head to press the spring into the cylinder.
User manual Planned maintenance
P/N 3-9008-556 October 2019
User manual 77