Cashco 521 - Manual (Page 12)

IOM-521 12
(Stem movement will stop when the plug
engages the seat.)
4. Slowly pressurize the ac tu a tor to a pres sure
equal to the upper pres sure lev el of the
bench setting; i.e. for a 5-15 psig (.34 -1.0
Barg) range, set pressure at 15 psig (1.0
Barg). Take note of the pressure reading
when stem travel actually stops.
5. If the loading pressure, when stem move-
ment stops, is below the upper end of the
desired bench setting, then the com bined
stem (9, 6) length is too long.
a. Rotate jam nut (20) down to base of
threads on stem (9).
b. Decrease pressure in the actuator to
approximately mid range of the bench
setting.
c. Rotate lower knuckle (44) CCW to
shorten the combined stem length. DO
NOT allow actuator stem (6) to rotate
in the actuator.
d. Release all pressure from the actuator
and repeat Step 4 previous.
6. If the loading pressure, when stem move-
ment stops, is above the upper end of the
desired bench setting, then the com bined
stem (9, 6) length is too short.
a. Rotate jam nut (20) down to base of
threads on stem (9).
b. Decrease pressure in the actuator to
approximately mid range of the bench
setting.
c. Rotate lower knuckle (44) CW to in-
crease the combined stem length. DO
NOT allow actuator stem (6) to rotate
in the actuator.
d. Release all pressure from the actuator
and repeat Step 4 previous.
7. Increase pressure in the actuator to the up-
per pressure level of the bench setting.
8. Observe the location of the in di ca ting washer
(51) to the "C" mark on the in di ca tor plate
(23), mak ing sure to use the “top edge” of
the in di ca ting washer (51) as the ref er ence
point. Adjust indicator plate as needed.
8. Remove vented pipe plug (12) from the neck
of the bonnet (2).
9. Slowly release air pressure in actuator until
indicating washer (51) is in alignment with
the “O” mark on the indicator plate (23).
NOTE: This "stop" should not function as
an up travel stop and push up against the
bonnet (2) (metal to metal). A gap of ap-
proximately 1/16" (1-1/2 mm) should exist
between these two surfaces.
NOTE: The purpose of a correct calibration
of the stem stroke is to cause the up travel
to be limited by the actuator travel stop nut.
10. To limit the up travel, rotate the travel stop
nut (52) CW and secure to bottom of attach-
ment hub (4).
NOTE: Secure the actuator stem (6) by the
fl ats when rotating the travel stop nut.
NOTE: "Stroke" length is indicated on the
nameplate (40), and is the distance between
the "C" and "O" marks of the indicator plate
(23).
NOTE: The proper calibration of the actua-
tor / valve unit will occur when at the lower
pressure level of bench setting the valve
plug (3) will just begin to travel from the "C"
position. At the upper level of the bench
setting, the actuator pressure should be
within ±8% of the upper bench range for
the desired stroke length.
11. Engage threaded, vented pipe plug (12)
into the 1/8" NPT tap on the bon net (2). If
a lubricating oil is compatible with the fl uid,
a light coat ing will aid in pre vent ing galling
of the plug (12). En sure that the tip of the
notch on the threads is in the bonnet (2) at
least 1-1⁄2 revolutions.
Do not over-tighten to min i mize chanc es of
galling.
Do not use thread sealing com pound that
might “fi ll in” the notch and negate the pur-
pose of the notch.
12. Release all pressure from actuator.
C. Procedure – Direct Action, ATC-FO:
1. Reference the nameplate (40) attached to
the actuator yoke (3). Determine the bench
set ting of the installed range springs (10)
from the nameplate (40).
2. Connect a temporary air supply with an in-
line ad just able airset regulator and gauge
to the upper actuator con nec tion. DO NOT
LOAD with any air pressure at this point.
3. To determine when stem/plug (3) makes
contact with the seat and travel stops, touch
the stem below the jam nut with one fi nger.