2.3.10
Inlet Air Filters
Provide a three-stage filter system, complete with mounting racks
(horizontal flow), interstage seals, and replaceable filters. Filter unit
shall be provided complete including enclosure or housing, and frames.
Enclosure shall be Class 5000 aluminum alloy with inlet and outlet flanges.
Construction shall be welded or, where welding is not practical, close
riveted and caulked, weathertight, with access doors for filter replacement
and cleaning. Access doors shall be reinforced, fully gasketed with
continuous flexible neoprene gaskets, corrosion-resistant continuous hinges
and quarter-turn latches to ensure tightness. All internal ferrous
surfaces, including galvanized, shall receive a factory-applied epoxy prime
and finish coat for corrosion resistance. Filters shall consist of three
separate stages and sized to fit the available space.
2.3.10.1
First-Stage Filter
First-stage filter shall be flat, 50 mm 2 inch thickness, replaceable
media, and rated for the required air quantity at 2.54 m/s 500 FPM nominal
face velocity, friction clean 62 Pa 0.25 inch water gage, efficiency 98
percent of 15 microns and 90 percent of 5 microns.
2.3.10.2
Second-Stage Filter
Second-stage filter shall be deep pleated type, 230 mm 9 inchesnominal
depth and rated for the required air quantity at 1.78 m/s 350 FPM nominal
face velocity, friction clean 50 Pa 0.20 inch watergage, efficiency 98
percent of 5 microns and 90 percent of 3 microns.
2.3.10.3
Third-Stage Filter
Third stage filter shall be deep pleated type 305 mm 12 inchesminimum depth
and rated for the required air quantity at 1.78 m/s 350 FPM nominal face
velocity, friction clean 75 Pa 0.30 inch watergage, efficiency 99.9 percent
of 0.5 micron.
2.3.10.4
Filter Media
Filter media shall be rated and listed UL Class 2. Filter efficiencies
shall be based on National Bureau of Standards (NBS) type discoloration
gravimetric test method using atmospheric dust.
2.3.11
Inlet Line Silencer
An inlet line silencer shall be furnished with each compressor as selected
by compressor manufacturer for sufficient noise attenuation to meet OSHA
sound level criteria but not greater than 84 dBA measured at an elevation of
1.50 meter 5 feet, and 3 meter 10 feet horizontally from silencer.
2.3.12
Sound Attenuating Enclosure
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NOTE: Provide sound attenuating enclosure or make
other provisions to comply with OPNAV 5100.23,
Chapter 18, paragraph 18202, "Preventive Measures,"
which contains noise abatement requirements for new
machinery and equipment. If manufacturers do not
furnish sound attenuating enclosure as a
SECTION 15214N
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