DOCUMENT 2529
REV. E
Instruction Manual
Model 4 – Style III
Taxiway Omni-directional Light L-852T
4
Every time the unit is opened, the o-ring must be closely examined and replaced, if necessary. Any o-ring
that is stretched, torn, has permanent set, or some other defect which would prevent it from forming a
watertight seal must be replaced with a new o-ring.
NOTICE:
NOTICE
A bad o-ring seal is the most common cause of inset fixture leaks. It is strongly
recommended that a new o-ring be installed every time the Optical Assembly is opened
Remove the old o-ring from the groove in the optical housing. Carefully clean the o-ring groove and flange
mating surface on the inner cover. Take care not to damage the mating surface or the o-ring. Coat the o-ring
(P/N 10035-62) with a thin layer of Dow Corning FS 1292 Lubricating grease. Position the new o-ring in
the center of the groove and press it into place. Torque the inner cover screws to 25 - 30 in-lbs. Perform a
pressure test as described in paragraph 8.6. Clean the mounting flange area of the base. Place the fixture
into the base. Apply Loctite 242 (P/N 10048-30), per manufacturer’s instructions, to all mounting bolts and
immediately torque them to 225 - 235 in-lbs.
NOTICE:
NOTICE
The groove is designed to be wider than the o-ring. This provides room for the
displacement of the o-ring when compressed between the housing and mating surface.
Properly tightened screws are important in obtaining a complete seal.
8.5
Lens/Heater Replacement
Outer Lens:
If an outer lens is broken, leaks, or is badly pitted or scarred, it must be replaced. It is highly recommended
that this task be performed in a clean shop environment. Outer Lens Replacement Kit P/N 21332 contains
all necessary parts to change a lens.
Remove and secure power to the fixture.
Turn the fixture
upside down and remove the four screws holding the inner cover to the light housing. Remove the lens retaining
bracket screws from the light housing. Remove the lens-retaining bracket and support ring and discard the lens-
retaining gasket. Firmly push the lens/boot assembly from the outside of the light housing; discard the old lens
and boot. Thoroughly clean the lens opening with isopropyl alcohol and let dry. Inspect the lens opening for
scratches or pits; a damaged lens opening surface will not seal properly. Place a new lens boot (P/N 21256)
over the replacement outer lens (P/N 21254). Apply a thin coat of Dow Corning FS 1292 grease over the
entire outside surface of the lens boot. Align the lens/boot assembly in the lens opening and press it into
place. Verify that the lens boot is not pinched in the lens opening. Using a new lens retaining gasket (P/N
21258), fasten the lens retaining bracket (P/N 21259) and support ring (P/N 21453) to the light housing.
Torque the mounting screws to 25 - 30 in-lbs; over tightening these screws may cause damage.
Inspect/replace the optical housing’s o-ring per paragraph 8.4. Assemble the inner cover onto the light
housing. The screw-hole patterns in the inner cover and light housing are offset to insure proper alignment.
Torque the mounting screws to 25 - 30 in-lbs. Perform a pressure test per paragraph 8.7. Clean the
mounting flange area of the base. Place the fixture into the base. Apply Loctite 242 (P/N 10048-30), per
manufacturer’s instructions, to all mounting bolts and immediately torque them to 225 - 235 in-lbs.
