Ashcroft 4480 - Pneumatic Transmitter - Manual (Page 9)

9
General
The assemblies and parts illustrated in Figures 8 and 9 and
listed in the Parts List are available for replacement purposes.
When a detail part not shown as a separate item requires
replacement, replace the assembly of which it is a part.
When a pressure transmitter has been purchased for one type
of service but is to be used for a different type of service, the
range and/or the material of the input system assembly may be
changed to meet the new requirements. In similar manner, the
pneumatic output range may be changed. In some cases
where the input system assembly is changed, and in most
cases where the output range is changed, a new flexure
assembly will be required.
To select the most suitable range and/or material for a new
input system assembly, refer to Product Catalog. To order a
new input system assembly, specify the desired input range
and material, the desired output range, and the present input
and output ranges. If a new flexure assembly is required, it will
be furnished with the input system assembly.
Input Element
To replace the input system assembly, refer to the applicable
illustration (Fig. 8 and 9) and proceed as follows:
a. Loosen two captive screws (31) and remove cover (36
or 36a).
Note: Steps b through g are required on indicating pressure
transmitters only.
b. Remove ring/case gasket (52) from ring (50).
c. Loosen two screws (51) and remove ring (50) from dial
(44), removing window (49) and ring/glass gasket (48)
from ring.
d. Being careful not to damage pointer, draw pointer
assembly (47) from shaft of movement (38). Use of hand
jack is recommended.
e. Remove two screws (46) and screw (45) and remove
dial (44) from movement (38).
f. Remove screw (4a) and separate link (4) from system
assembly (2).
g. If necessary to remove movement (38), remove screw
(40) and post (39) securing movement to system
assembly (2).
h. Remove relay assembly and gasket (17) from body
assembly (7b) by removing two screws (20) and lock-
washers (21).
i. Remove three screws (8) securing system assembly (2)
to body assembly (7, 7a or 7b).
j. Loosen two screws (1h) securing clamp (1b) to base
plate assembly (1).
k. Loosen allen head screw (1k) and lift system assembly
(2) from clamp (1b).
l. Break adhesive bond by heating screw (4) securing zero
adjusting assembly (3) to system assembly (2) and
remove screw and zero adjusting assembly.
Note: On indicating pressure transmitters, break adhesive
bond by heating nut (5) securing zero adjusting assem-
bly and remove nut and zero adjusting assembly. On
short span pressure transmitters, remove vane assem-
bly (3a) by removing two screws (4b).
m. Install new system assembly by performing the above
procedures in reverse. After system assembly has been
secured in position, align zero adjusting assembly so
that slot is vertical. Secure by applying Devcon 2 ton
epoxy adhesive and assembling and tightening screw
(or nut). Machine or file back side of tip on bored tube
systems to a
3 ⁄
82
thickness.
Note: If necessary, bend vane of zero adjusting assembly so
that vane is centered in slot of flexure assembly.
n. After replacement of system assembly, calibrate pres-
sure transmitter as described in the Calibration section.
Note: Replacement systems ordered from factory will have
zero adjusting assembly attached.
Flexure and Nozzle Assembly
To replace the flexure assembly, refer to the applicable illustra-
tion (Fig. 7 through 9) and proceed as follows:
a. Remove tubings (22c) from nozzles on flexure assembly
(13).
b. Remove nut (16) securing flexure assembly (13) to feed-
back bellows of body assembly (7, 7a or 7b).
c. Remove two screws (15) and clamping plate (14) and
remove flexure assembly (13) from body assembly (7,
7a or 7b).
d. Install new flexure assembly by performing the above
procedure in reverse.
e. After replacement of flexure assembly (13) calibrate
pressure transmitter as described in the Calibration
section.
Pneumatic Relay Assembly Parts
To disassemble the relay assembly, follow the sequence of the
index numbers shown in Figure 10. Disassemble only to the
extent necessary for cleaning, inspection, and replacement of
parts. Take care not to deform diaphragms or springs during
disassembly and reassembly. Reassemble in the reverse order
of the index numbers shown in Figure 10.
REMOVAL AND REPLACEMENT OF PARTS
I&M008-10061-1-01 250-1969-C_I&M008-10061-1/01 250-1969-C 12/20/13 9:09 AM Page 9