then use continuous seam welding to seal RF seams in the enclosure. Do not
allow slag inclusions, gas pockets, voids, or incomplete fusion anywhere
along continuous welded seams. Be aware that welds which seem highly
satisfactory upon visual inspection may fail the electromagnetic test.
Correct weld failures by grinding out such welds and replacing with new
welds. Perform welding, both structural and RF sealing, by employing a
welder certified competent for MIG welding in all positions in accordance
with the Standard Qualification Procedure of AWS D1.1/D1.1M.
3.2
DOOR ASSEMBLIES
Mount so that the clearance between the door edges and frame shall not vary
more than 2 mm 1/16 inch and the innerface of the door periphery does not
vary more than 2 mm 1/16 inch from the plane of the door stop's face.
Through-bolt hinges to the door and the frame.
3.3
LINE FILTERS
Provide filters for incoming electrical power lines [, including neutrals,]
and for incoming telephone and signal lines. Support filters independently
of the shielding.
3.4
WAVEGUIDE-TYPE AIR VENTS
[Provide each inlet and return air duct with the number and size of
waveguide-type air vents at each location where the ducts enter the
shielded enclosure.] [As a minimum, provide each enclosure with one 300 mm
12 inch square inlet and one 300 mm 12 inch square return waveguide-type
air vent.]
3.5
EXHAUST FAN
Mount on [wall] [or] [ceiling] over the exhaust vent on the exterior
surface of shielded enclosure. Provide power from electrical source
exterior to the shielded enclosure.
3.6
CONDUCTOR INSTALLATION
Provide filtered conductors in conduit, except for coaxial cable, from
filter to shielding and penetrate the enclosure through threaded rigid
steel conduits. [Twist conductors leading from the filters and conductors
inside the shielded enclosure approximately 30 turns per meter 10 turns per
foot in the conduit.]
3.7
GROUNDING
**************************************************************************
NOTE: If not specified in Division 16,
"Electrical," the following sentence shall be added:
"Wires inside the enclosure and for a distance of at
least 15 meters 50 feet outside of the enclosure
shall be enclosed in a grounded, threaded rigid
steel conduit system."
**************************************************************************
Extend the grounding stud through and [bolt] [weld] stud to the electrical
power panel with a minimum No. 4 AWG insulated stranded copper conductor to
effectively serve as a single grounding point for the completely assembled
shielded enclosure, both internally and externally.
SECTION 13094N
Page 17
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