25
Model 764 Differential Pressure Transmitter
Section 4
Transmitter Cover Removal
!
WARNING: Never pry on the transmitter cover to remove it. The trans-
mitter cover and/or case may be damaged. Operating a transmitter with
a damaged cover and/or case may result in a serious degradation of
transmitter performance during design basis events, resulting in a poten-
tial degradation of safety systems. To avoid the potential for equipment
degradation, remove the cover using the procedure provided below.
An O-ring seal installed between the transmitter cover and the housing
protects the internal circuitry from moisture during design basis events. Two
threaded jackholes assist in the removal of the transmitter cover.
To remove the transmitter cover, perform the following steps:
1. Remove the eight cap screws from the transmitter cover using an Allen-
head wrench.
2. Insert a cap screw into each of the threaded jackholes on the transmitter
cover.
3.
Tighten the cap screws to break the seal between the cover and the O-ring.
4.
Remove the cap screws from the jackholes and lift the cover from the
instrument.
Transmitter Cover Reinstallation
IMPORTANT: Replacement of the transmitter cover O-ring is recommended each time
the transmitter is disassembled. Replacement O-rings must be identical
to those removed. Consult the parts list (Table 5.1,
page 33
) for the
correct part numbers.
To install the transmitter cover, perform the following steps:
1. Apply a small amount of silicone grease to the O-rings.
2. Install the O-rings into their respective grooves.
!
WARNING: Do not allow the cover O-rings to unseat and become pinched
between two surfaces during cover installation. Operation of a transmitter
with damaged O-rings may result in serious degradation of transmitter
performance during design basis events resulting in a potential degrada-
tion of safety systems. To avoid the potential for O-ring damage during
cover installation, visually inspect the O-rings as the cover screws are
tightened.
3.
Carefully install the transmitter cover on the transmitter case.
4.
Replace the eight cap screws and torque to 3-6 ft-lb (dry).
