COPES-VULCAN INSTRUCTION MANUAL
MODEL 700 DIRECT-ACTING ACTUATOR
Rev.5 (08/10) Page 7 of
20 Form 01:P224:37
2.3 STEM CONNECTOR AND TRAVEL ADJUSTMENT
2.3.1 Direct-Seated Valve Without Backseat
A direct-seated valve is closed by applying downward force on the valve stem.
For the case of a direct-seated valve where a valve backseat is not present, the actuator will be set
up so that upward, or opening, motion of the valve stem is limited by the internal stop in the
actuator and downward, or closing, motion of the stem will be limited by the valve mainseat.
Note that Tandem valve trim, which has an internal valve spring, requires a different procedure
than that outlined below and is discussed separately in this section. For other trim types, proceed
as follows:
A. Referring to the assembly drawing and to Figure 1, place the stem lock plate (Item 28) over
the valve stem, then thread the stem clamp (Item 27) fully on the valve stem thread. Thread
the upper stem weldment (Item 22) onto the actuator stem (Item 16) so that the bottom
surface of the upper stem weldment is approximately 0.06" (1.5 mm) above the bottom of the
actuator stem.
B. Refer to the valve specification sheet for the required valve travel. With the actuator fully
open and the valve seated, adjust the position of the stem clamp on the valve stem so that
the distance from the bottom of the actuator stem to the top surface of the stem clamp is
equal to the desired travel. Tighten the setscrew in the stem clamp to 15 ft-lb (20 Nm). Note
that, for proper seating to occur, the available travel of the actuator must be larger than the
required valve travel.
C. Connect an air line to the NPT connection in the upper diaphragm casing. Slowly increase air
pressure and allow the bottom of the actuator stem to contact the stem clamp on the valve
stem. Do not permit air pressure to exceed 80 psig (5.5 bar).
WARNING! Never exceed the actuator allowable air pressure rating. Property
damage, injury or death may occur.
D. Pull up the stem lock plate and install the four 7/16"-14 socket head cap screws (Item 23)
with lockwashers (Item 24). Torque the cap screws to 24 ft-lb (33 Nm). Maintain parallelism
between the stem lock plate and the upper stem flange.
E. If necessary, adjust the position of the indicator plate (Item 8 on the assembly drawing).
2.3.2 Direct-Seated Valve With Backseat
The stem connector is assembled in the same manner as detailed in Section 2.3.1 except that, in
Step B, adjust the air pressure so that the actuator stem is approximately 1/8" (3 mm) away from
the fully open position. Some trial-and-error adjustment of the position of the stem clamp on the
valve stem may be required to assure that proper mainseat and backseat contact is achieved.
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