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Cashco 521 User Manual

Page 11

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IOM-521

11

15. For Direct Action ATC-FO Only: Release

all air pressure from actuator assembly (AA),
see step 9 previous and remove temporary
air supply.

16. Re-tighten packing gland nut (5).

VI. CALIBRATION

A.

General:

1. This section only covers calibration of this

control valve with Actuator Models C27-C53.

2. Positioner, if installed, requires reference to

the spe cifi c positioner model IOM for proper
cal i bra tion pro ce dure.

3. All indicated Item Num bers that are with

re spect to IOM-C27-C53 will be in pa ren-
the sis and un der scored; i.e. (20). All Item
Num bers that are with respect to this IOM-
521 are not un der scored; i.e. (32).

B. Procedure – Reverse Ac tion, ATO-FC:

1. Reference

the

name

plate (40) at tached to

the actuator yoke (3). De ter mine the bench
set ting of the installed range springs (10)
from the name plate (40).

2. Connect a temporary air supply with an in-

line ad just able airset reg u la tor and gauge
to the lower actuator con nec tion. DO NOT
LOAD
with any air pressure at this point.

3. To determine when stem/plug (9) begins to

lift out of the seat, touch the stem below the
jam nut with one fi nger. (Stem will begin to
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 level of the bench
setting; i.e. for 5-15 psig (.34–1.03 Barg)
range, set pressure at 5 psig (.34 Barg).
Take note of 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 (9, 6) length is too short.
a. Rotate jam nut (20) down to base of

threads on stem (9).

SECTION VI

b. Increase pressure in the actuator to

approximately mid range of the bench
setting.

c. Rotate lower knuckle (44) CCW 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.

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 (9, 6) length is too long.
a. Rotate jam nut (20) down to base of

threads on stem (9).

b. Increase pressure in the actuator to

approximately mid range of the bench
setting.

c. Rotate lower knuckle (44) CW 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.

7. 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 increase the pressure in the actuator

until the indicating washer (51) is in align-
ment with the "O" mark on the indicator plate.
As pressure increases, thru the hole where
the vent ed pipe plug (12) was re moved,
watch for the anti-ro ta tion al "stop" (square
or fl at surface of the stem) to appear.

17. Tighten yoke nut (15) to 85 ft--# (115 N-M)

18. Calibrate actuator to valve per Section VI.