sequence to check for binding as described in step 9
above.
5
ACTUATOR MOUNTING AND
ADJUSTMENT
5.1
General
The following instructions are for the traditional D/R series
spring /diaphragm actuator. Instructions for other actua-
tors can be obtained from your local representative.
5.2
Actuator Mounting
1. Lower the actuator over the plug stem and packing
flange to seat squarely on the bonnet shoulder.
2. Rotate the actuator to a convenient position, then
screw the clamp nut onto the valve bonnet threads and
tighten it securely.
3. Connect a regulated air supply to the actuator
diaphragm connection. The supply should be at least 5
psig greater than the pressure needed to stroke the
actuator.
4. The actuator must be in the down position on the
down travel stop.
NOTE:
For "R" series actuators, the spring will maintain the
actuator on the down travel stop and no air pressure is
required. For "D" series actuators, regulate the supply pres-
sure to the actuator to move the actuator stem downward
until the downward motion is the same as the travel listed
in Table 2.
5. The valve plug must be on its seat while the actuator
stem is being connected.
6. Press half of the actuator coupling against the actuator
stem and valve plug stem so that each stem is engaged
in the coupling half at least one stem diameter.
NOTE:
It may be necessary to move the valve plug off its
seat a slight distance in order to mesh the valve plug stem
threads with the coupling threads.
7. Apply the other half of the coupling, carefully engaging
threads, then insert the coupling cap screw and tighten
it by hand (Refer to Figure 1).
5.3
Establishing Seat Load
1. Maintain the actuator stem at its lowest position of
travel.
2. If the plug moved off the seat during the stem connec-
tion procedure, prevent the stem coupling from rotat-
ing, and unscrew the valve plug stem out of the cou-
pling until the plug is seated.
CAUTION: UNSCREW THE PLUG STEM UNTIL THE SEAT IS
CONTACTED. DO NOT CONTINUE TO UNSCREW. ROTAT-
ING THE VALVE PLUG WHILE IN CONTACT WITH THE SEAT
RING CAN CAUSE DISTRUCTION OF THE SEAT AND
GALLING.
3. Move the plug off the seat by adding air supply to the
"R" series actuator or decreasing air supply to the "D"
series actuator. Unscrew the valve plug stem an addi-
tional one-half turn out of the actuator coupling to
ensure positive seating.
4. Tighten the connector cap screws securely.
5. Seat the valve plug firmly by means of the actuator.
IMPORTANT NOTICE
If these steps have been performed correctly the valve
plug is on the seat ring, the actuator has been raised
upward off its down travel stop, the actuator thrust is
applied to the valve trim, and valve leakage will be within
acceptable limits. If maintenance work has been per-
formed and seat leakage is exceptionally high, these steps
should be repeated in order to ensure that adequate seat
load has been established.
5.4
Valve/Actuator/Travel
1. Adjust the travel indicator scale on the actuator yoke
leg so that the "Shut" mark is opposite the travel indi-
cator on the actuator stem coupling.
2. Stroke the valve/actuator combination by regulating
the air supply to the diaphragm case. Note the travel on
the indicator scale.
3. The actual travel should agree with the travels listed in
Table 2.
NOTE
: If the actual travel is less than the travel listed in
Table 2, the actuator coupling should be removed and the
steps in the previous sections repeated.
5.5
Actuator Bench Set and Span
1. The actuator bench set (spring preload) is stamped on
the actuator identification tag located on the actuator
leg.
2. Using a regulated air supply with a gage connected
between the regulator and the diaphragm case, stroke
the valve actuator combination.
3. Record the actuator air pressure at the actuator full up
and full down position.This is the bench set and should
agree with the bench set stamped on the identification
tag.
4. If the actual bench set does not agree with the identifi-
cation tag, the bench set can be adjusted by rotating
the actuator spring adjuster.
5. The actuator spring span is the arithmetic difference
between the bench set upper limit and lower limit.
7
