designated as "mercury-free."
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Provide inclined-type manometers for filter stations of 944 L/s 2,000 cfm
capacity or larger including filters furnished as integral parts of
air-handling units and filters installed separately. Provide sufficient
length to read at least 250 Pa one inch of water column with 10 major
graduations, and equipped with spirit level. Equip manometers with
overpressure safety traps to prevent loss of fluid, and two three-way vent
valves for checking zero setting. [Mercury shall not be used as the
operating fluid.]
2.7
COATINGS FOR FINNED TUBE COILS
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NOTE: Include this article when coating of finned
tube coils is required by the equipment
specifications paragraph.
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NOTE: Research project location conditions to
determine the environmental effects on finned tube
coils. The research should include a survey of
existing similar equipment. If needed, rewrite the
specifications based on the conclusions of the
research. Consideration should be given to the
following combinations based on past experience of
these materials in dealing with the local conditions.
1.
Copper tube and aluminum fins, coated;
2.
Copper tube and copper fins, coated;
3.
Aluminum tube and aluminum fins, coated;
4.
Aluminum tube and aluminum fins, uncoated;
5.
Copper tube and copper fins, uncoated; and
6. Copper tube and aluminum fins, uncoated.
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Where stipulated in equipment specifications of this section, coat finned
tube coils of the affected equipment as specified below. Apply coating at
the premises of a company specializing in such work. Degrease and prepare
for coating in accordance with the coating applicator's procedures for the
type of metals involved. Completed coating shall show no evidence of
softening, blistering, cracking, crazing, flaking, loss of adhesion, or
"bridging" between the fins.
2.7.1
Phenolic Coating
Provide a resin base thermosetting phenolic coating. Apply coating by
immersion dipping of the entire coil. Provide a minimum of two coats.
Bake or heat dry coils following immersions. After final immersion and
prior to final baking, spray entire coil with particular emphasis given to
building up coating on sheared edges. Total dry film thickness shall be
0.064 to 0.076 mm 2.5 to 3.0 mils.
SECTION 15730N
Page 22
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