I-768N
/ Series 768N FireLock NXT
™
Dry Valve
/ Installation, Maintenance, and Testing Manual
CAUTION
• DO NOT over-tighten the cover plate bolts.
Failure to follow this instruction could cause damage to the cover
plate gasket, resulting in valve leakage.
4.
Align the cover plate/cover plate gasket to the valve. Ensure that
the clapper spring’s arms are rotated to their installed position.
Tighten all cover plate bolts into the cover plate/valve body.
5.
Torque all cover plate bolts in an even, crossing pattern. Refer
to the “Required Cover Plate Bolt Torques” table below for the
required torque values. DO NOT over-tighten the cover plate bolts.
REQUIRED COVER PLATE BOLT TORQUES
Nominal Size
inches or mm
Required Torque
ft-lbs/N•m
1 ½
30
41
2
30
41
2 ½
60
81
76.1 mm
60
81
3
60
81
4
100
136
165.1 mm
115
156
6
115
156
8
100
136
6.
Place the system back in service by following the “Resetting the
System” section.
REMOVING AND REPLACING THE DIAPHRAGM
1.
Remove the system from service by following steps 1 – 10 of the
“Required Internal Inspection” section.
2.
Break the unions that connect the trim to the diaphragm cover.
Refer to the applicable trim drawing for details.
3.
Remove the cap screws from the diaphragm cover, and pull the
diaphragm cover/trim off the valve.
4.
Remove the diaphragm from the valve body. Discard the
diaphragm.
5.
Clean the back of the valve body to remove any debris that may
interfere with proper diaphragm seating.
5a.
Clean the inside of the diaphragm cover.
CAUTION
• Use caution when installing a new diaphragm into the valve
body.
Failure to follow this instruction could cause damage to the
diaphragm, resulting in improper valve operation and valve leakage.
I-768N_30
REV_C
