Note
To protect against reduced performance,
ensure vents are not plugged when
conducting routine maintenance.
• Before maintenance, close the inlet and outlet block
valves and exhaust the pressure in the valve body
and piping as described in the Shutdown section.
• When removing or replacing parts such as the
orifice or diaphragm, be careful not to damage it.
• Ensure movable parts can move freely
after reassembly.
• Recommission according to the Installation and
Startup procedures.
• Ensure all connections are tight and check for leaks.
Regular Maintenance
1. Make sure that there is no leakage on the
backpressure regulator and tubing connections.
2. Observe the gauges to make sure that the
pressure being controlled is stable and at the
correct set point.
3. Ensure the pipeline system is clean and free of
foreign materials.
Periodic Maintenance
1. Check Type CT88 backpressure regulator reseat
pressure. Slowly increase the inlet pressure until
the outlet pressure starts to rise, then slowly
decrease the inlet pressure until the outlet
pressure stabilizes. Ensure that the downstream
pressure does not increase.
2. Clean wear parts like the Disk, Diaphragm and
Seat Ring. Make sure to check and replace
deformed and worn out seals when necessary.
3. Check wear parts for damage and replace when
necessary, replace O-rings after disassembly.
Maintenance Instructions for Actuator
Replacement Parts (keys 15, 21, 22, 23,
56 and 68)
Refer to Figure 4 for the Type CT88 Actuator
Assembly, Figure 5 for the NPS 2 / DN 50 body
assembly drawing and Figure 6 for the NPS 3 and 4 /
DN 80 and 100 body assembly drawing.
Actuator Disassembly
1. Isolate the Backpressure Regulator, relieve all
pressure in body and actuator and relieve spring
force by following the procedure described in the
Shutdown section.
2. Loosen and remove sense line from diaphragm
lower casing (key 54).
3. Loosen and remove 8 bolts (key 58), 8 nuts
(key 57) and 8 washers (key 8) around the
actuator flange.
4. Lift the upper casing (key 59) directly upward over
the main spring (key 48). Set aside spring and
upper spring seat (key 50).
5. Loosen and remove 2 hex nuts (keys 60 and 34)
from stem (key 14)
(1)
.
6. Remove lower spring seat (key 37), diaphragm
plate (key 55) diaphragm (key 56), diaphragm
head (key 36) and O-ring (key 68) upward and
over stem (key 14)
(1)
. Do not damage or remove
pin (key 66) from diaphragm head (key 36).
7. Loosen and remove 4 screws (key 16) and
4 spring washers (key 17).
8. Carefully remove diaphragm lower casing (key 54)
upward and over stem (key 14).
9. Remove bushing (key 20), 2 stem guides (key 21),
O-rings (keys 22 and 23) upward over the stem
(key 14).
10. Remove O-ring (key 15).
Actuator Assembly
1. Lightly lubricate O-ring (key 15) and place it into
the body.
2. Carefully place the diaphragm lower casing on
the body, make sure the thread holes on both
of casing and body are aligned. The position of
sense line pipe hole should be aligned with the
sense line pipe hole of the body.
3. Place spring washers (key 17) on screw (key 16),
apply lubricant to the thread of bolts.
4. Bolt body and casing together and tighten screws
(key 16) securely using a multi-pass, criss-cross
pattern. Torque values listed in Table 4.
5. Lightly lubricate O-ring (key 68) and mount it into
the groove of diaphragm head (key 36); Insert the
stem (key 14) through center of the diaphragm
head, and press until it makes contact with
1. Refer to Figures 5 and 6.
6
Type CT88
