Cashco 987 - Manual (Page 8)

8 IOM-987
Use the total number of revs en gage ment
recorded in Step V.B.4. as the guide to con-
trol engagement of the stems (6) (4). While
en gag ing the stems, rotate yoke nut (15) as
able to help stabilize top works, continue to
pres sur ize the ac tu a tor in 2-3 psi (.15-.20 Bar)
in cre ments in an al ter nat ing se quence with
the distance en gaged until the total num ber
of revs engaged is reached.
30. Hand-tighten yoke nut (15) until fully po si tioned
with the yoke (3) sitting on the bonnet (2).
31. Secure “dangling parts” - ac ces so ry plate ((AP))
and indicator washer (16) - to ac tu a tor stem (6)
with stem jam nuts (17).
32. Ham mer rap yoke nut (15) until tight. (Release
tem po rary air source.)
33. Install nuts (21) on studs (20). Use torque wrench
to tighten to 25-30 in-lbs.
SECTION VI
VI. CALIBRATION
A. General:
1. This section only covers cal i bra tion of the
control valve with Actuator Models C27/C53.
2. Positioner, if in stalled, requires ref er ence to
the spe cifi c positioner mod el IOM for prop er
cal i bra tion pro ce dure.
3. All indicated items numbers that are with
re spect to IOM-C27-C53 will be in pa ren-
the sis and un der scored; i.e. (20); those that
reference the po si tion er IOM will be in double
paranthesis; i.e. ((AP)). All item numbers
that are with respect to this IOM-987 are not
un der scored; i.e. (3).
B. Procedure - Reverse Action, ATO-FC:
1. Reference the name plate (40) at tached to
the ac tu a tor yoke (3). De ter mine the bench
set ting of the in stalled range springs (10) from
the name plate (40); i.e. 5-15 psig (.34 -1.0
Barg), or 15-60 psig (1-4.1 Barg).
2. Connect a temporary air supply with an in-
line ad just able airset regulator and gauge to
the lower actuator con nec tion. See Section
IV.A.6 for appropriate supply pressure. DO
NOT LOAD with any air pressure at this point.
3. To determine when stem/plug (4) begins to lift
out of the seat, touch the stem below the jam
nuts with one fi nger. (Stem will move when
actuator pressure exceeds the spring load.)
4. Slowly pressurize the ac tu a tor to a pres sure
equal to the lower pres sure lev el of the bench
setting; i.e. for a 5-15 psig (.34 -1.0 Barg)
range, set pressure at 5 psig (.34 Barg). Take
note of the pressure reading when the stem
fi rst begins to move.
5. If the loading pressure for the start of stem
movement is below the lower end of the
desired bench setting, then the com bined stem
(4, 6) length is too short.
a. Rotate both jam nuts (17) down to base of
threads on stem (4) and tighten together.
b. Increase pressure in the actuator to ap-
proximately mid range of the bench setting.
c. Rotate upper jam nut CW to increase the
combined stem length. DO NOT allow
actuator stem (6) to rotate in the actuator.
d. Rotate upper jam nut CCW to hold indicat-
ing washer (16) up against stem (6).
e. Release all pressure from the actuator and
repeat Step 4 previous.
6. If the loading pressure for the start of stem
movement is above the lower end of the
desired bench setting, then the com bined stem
(4, 6) length is too long.
a. Rotate both jam nuts (17) down to base of
threads on stem (4) and tighten together.
b. Increase pressure in the actuator to ap-
proximately mid range of the bench set.
c. Rotate lower jam nut CCW to shorten the
combined stem length. DO NOT allow
actuator stem (6) to rotate in the actuator.
d. Rotate upper jam nut CCW to hold indicat-
ing washer (16) up against stem (6).
e. Release all pressure from the actuator and
repeat Step 4 previous.
7. After the opening set point pressure has been
established, rotate lower jam nut (17) CCW up
tight under the upper jam nut.
8. Release all pressure from the actuator.
9. Observe the location of the in di ca ting washer
(16) to the "C" mark on the in di ca tor plate
(23), mak ing sure to use the “top edge” of the