Assembly - Emerson Fisher 667NS2 Instruction Manual

667NS2 Actuator
March 2022
11. Remove the set snap ring (key 172). Take the retainer thrust plate (key 165) out of the gear case (key 151).
12. Take out the parts in the following order: the gear retainer, the thrust bearing, the worm gear, and the second
thrust bearing (keys 162, 160, 161, and 160).
13. Unscrew the set screw (key 170), then, unscrew the handwheel cap (key 156) off the worm shaft (key 154).
14. Remove the handwheel (key 159) off the worm shaft (key 154). Do not lose the ball and the spring (keys 158 and
157).
15. Loosen the two set screws (key 170), and unscrew the front and back worm retainer (keys 155 and 152). The ball
bearing (key 153) will come out with the retainers.
16. Remove the worm shaft (key 154).
17. Unscrew the cap screws and washers (keys 169 and 175), and lift the gear case (key 151) and key (key 166) off the
yoke (key 109).
18. Remove the key (key 166) from the bottom of the gear case (key 151).

Assembly

Size 45 and 70 Actuators
Key number references are shown in figures 4 and 5 for size 45 and 70 actuators.
1. Place the spring (key 110) into the yoke (key 109). Coat the sealing surface of the yoke with NyoGel 718B (key 149),
as appropriate to the installation, and place the gasket on top of the yoke. Coat the top surface of the gasket (key
123) with NyoGel 718B (key 149).
2. Apply Loctite 242 (key 185) to the lower diaphragm casing hex cap screws (key 114). Attach the lower diaphragm
casing (key 122) to the yoke with the cap screws (key 114). Tighten the cap screws to 41 NSm (30 ft•lbf) of torque
for the size 45 actuators, and 102 NSm (75 ft•lbf) of torque for the size 70 actuators. Insert and evenly tighten the
cap screws using a crisscross pattern.
3. Install two O-rings (key 117) into the grooves in the inner diameter of the seal bushing (key 116). Install one O-ring
(key 118) into the groove in the outer diameter of the seal bushing (key 116).
4. Lubricate the O‐rings, and fill the seal bushing with NyoGel 718B (key 149) as appropriate to the installation, and
reinstall the bushing in the top of the yoke. Secure with the snap ring (key 124).
5. Coat O­ring (key 193) with NyoGel 718B (key 149) and install it to the groove of the stem. Apply Loctite 242 (key
185) to the travel stop spacer nut (key 111). Stack and assemble the diaphragm (key 105) and upper diaphragm
plate (key 107) with the stem by tightening the travel stop spacer nut to 183 N•m (135 ft•lbf). Apply Loctite 242
(key 185) to the cap screws (key 195) and bolt the lower diaphragm plate (key 108) to the upper diaphragm plate.
Torque the cap screws to 23 N•m (17 ft•lbf), then place this assembly in the actuator. Take care when pushing the
actuator stem through the seal bushing so that the threads do not damage the O‐rings. Orient the flat side of the
actuator stem so that it faces towards an open window of the yoke (recommendation is facing to the opening to the
right of the word "FISHER" on the yoke). See figure 4.
Note
When you replace actuator diaphragms in the field, take care to ensure the diaphragm casing bolts are tightened to the proper
load to prevent leakage, but not crush the material. Perform the following tightening sequence with a manual torque wrench for
size 45 and 70 actuators.
CAUTION
Overtightening the diaphragm casing cap screws and nuts (keys 119 and 120) can damage the diaphragm. Do not exceed a
torque of 27 NSm (20 ftSlbf) when performing the following tightening procedure.
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Instruction Manual
D103472X012