b) Dynamic type in which the air is compressed by the mechanical
action of rotating impellers or vanes.
Both types are available in either single-stage or multi-stage.
Applications and Requirement. Compressed air is divided into two
categories, plant air and instrument air.
Plant Air. Plant air is compressed to 125 psig (863 kPa) and is
maintained in the 90 psig (621 kPa) to 125 psig (863 kPa) range. It can be
used for the following:
a) Fuel oil atomizing at pressures from a few inches of water to 30
psig (207 kPa) or above. Demand must be confirmed with burner manufacturers.
Refer to paragraph 5.2.3 in this handbook.
b) Soot blowing. Normal design pressure for heating plants would
be 100 to 120 psig (690 to 828 kPa). Demand should be confirmed by boiler
manufacturers or soot blower manufacturers.
c) Baghouse pulse-jet cleaning,
e) Ash-silo fluidizing stones,
f) Tube expander,
g) Tools and miscellaneous usage,
h) Controls and valve actuators.
Instrument Air. Instrument air is air compressed in an oil free
compressor or a compressor with a minimum of oil carry-over to a pressure of
100 psig (690 kPa), dried to a dew point temperature not higher than 35
degrees F (1.7 degrees C) for indoor applications. The dew point at line
pressure shall be at least 18 degrees F (10 degrees C) below the minimum
ambient air temperature in the plant. For outdoor air lines the dew point at
line pressure shall be at least 18 degrees F (10 degrees C) below the minimum
recorded temperature at the plant site (see ANSI/ISA 57.3, Quality Standard
for Instrument Air, and NAVFAC DM-3.05, Compressed Air and Vacuum Systems,
Section 3). Outdoor pneumatic instruments should not be used in extremely
Refer to NAVFAC DM-3.05, Section 4.
a) Two or more compressors sized so that with one compressor off
line, the remaining compressors can handle 100 percent of the plant and
instrument compressed air requirements. The compressors should be sized so