Emerson Process Management 667 - Manual (Page 6)

Instruction Manual
D100311X012
667 Size 80 and 100 Actuators
May 2011
6
When adjusting travel of a direct‐acting valve, put a slight pressure on the actuator diaphragm. This moves the valve
plug off the seat, reducing the chance of damaging the valve plug or seat during adjustments.
1. Back the stem jam nuts (key 69, figures 6 and 7) away from the stem connector (key 31, figures 6 and 7), and
slightly loosen the stem connector cap screws.
CAUTION
Do not use wrenches or other tools directly on the valve stem. Damage to the stem surface and subsequent damage to the
valve packing may result.
2. Tighten the locknuts together, using a wrench, then screw the valve stem either into the stem connector to
lengthen travel or out of the stem connector to shorten travel.
3. Cycle the actuator to check for the specified travel. If actual travel is not equal to the specified travel, adjust and
check travel until correct. Tighten the stem connector cap screws when correct travel is obtained.
4. Raise the travel indicator disk by threading the stem locknuts against the stem connector.
Spring
Make spring adjustments when the loading pressure range applied to achieve specified travel is not equal to the
pressure range stamped on the actuator nameplate. Refer to the Bench Set pressure range on the nameplate when
the valve contains no pressure and the packing is loosely inserted in the bonnet. Refer to the Maximum Allowable
Supply pressure on the nameplate when the valve is controlling the specified pressure drop, and the packing is
tightened to stop leaks around the stem.
Monitor loading pressure carefully when making adjustments. Do not exceed the pressure specifications of either the
loading regulator or the actuator casings.
Each actuator spring has a fixed pressure span. Changing the spring compression shifts the span up or down to make
valve travel coincide with the loading pressure range.
Size 80 Actuator Spring
Note
Before turning the spring adjuster on size 80 actuators, assemble the stem connector around the actuator stem and the
anti‐rotating lug on the yoke. Mark the actuator stem as a visual reference to verify that stem rotation does not occur. Remove the
stem connector before rechecking the bench set.
Remove the cover band (key 87, figure 6), insert a rod of approximately 12.7 mm (1/2 inch) diameter into a hole in the
spring adjustor (key 74, figure 6), and rotate the spring adjustor with the rod. Rotating the adjustor from left to right
will increase the loading pressure required to start actuator stem travel; opposite rotation will decrease the pressure
required to start travel.
Size 100 Actuator Spring
CAUTION
The actuator must be in the vertical position when adjusting the spring to avoid damage to the thrust bearing (key 86,
figure 7) and to properly position the spacers required for adjustment.