be plus or minus 2 percent of the range.
Gages shall conform to
ASME B40.1.
b.
Gages indicating pneumatic outputs shall have 2 inch diameter
faces. Scale shall be 0 to 30 psi, with 1 psi graduations.
c.
Gages for low differential pressure measurements shall be 4 1/2
inch (nominal) size with two sets of pressure taps, and shall have
a diaphragm actuated pointer, white dial with black figures, and
pointer zero adjustment. Gage shall have ranges and graduations
as shown. Accuracy shall be plus or minus 2 percent of scale
range.
2.7
PNEUMATIC POWER SUPPLY AND TUBING
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NOTE: Delete the following section if pneumatic
actuators are not used in this specification.
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NOTE: Show compressed air station location on the
control drawings.
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2.7.1
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NOTE: Provide duplex air compressors for systems
having greater than 50 control air users or
requiring greater than 1.5 CFM of air. Size duplex
system air compressors for 50 percent run time and
simplex systems for 33 percent run time. Show power
sources for compressors, dryers and alternators.
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Provide tank mounted, [duplex,] electric motor driven, oil type, air
cooled, reciprocating type air compressor including motor, controller,
pressure switch, belt guard, pressure relief valve, and automatic moisture
drain valve. Piston speed shall not exceed 450 fpm. Set relief valve for
10 to 25 psig above the control switch cut-off pressure. Pressure switch
shall start compressor at 70 psig and stop compressor at 90 psig. Size
[each] compressor to run not more than [33] [50] percent of the time with
full system control load. Compressor shall have maintaining type starter
for automatic restart after power failure. [Provide duplex air compressors
with electric alternator switch assembly.] Motors 0.5 hp and larger shall
be three-phase, 208 or 460-volt, 60 Hz.
2.7.2
Compressed Air Tank
Provide steel tank constructed and labeled in accordance with ASME BPVC
SEC VIII for a minimum of 125 psig working pressure. Tank shall be of
sufficient volume so that the run time is not more than 50 percent for
duplex or 33 percent for simplex units.
2.7.3
Intake Air Filter and Silencer
Provide dry-type combination intake air filter and silencer with baked
enamel steel housing. Filter shall be 99 percent efficient at 10 micron
SECTION 15910N
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