be strong acid, alkaline, or otherwise corrosive
to the internal surfaces or lubricants of the
compressor. In addition, gases or fumes may be
prohibited by the end-use process, such as medical
gases or breathing air and for environmental or
odor reasons. Intakes near normal flow paths of
engine exhausts should be avoided.
Oil fumes, vapor, or mist can be as difficult
to handle as particulate or gases. Even though
many types of compressors are oil lubricated, the
oil ingested may not be compatible and com-
pressor load may be increased.
Waste and water vapor are always present in
air intakes. Installation of intakes should prevent
the accumulation of free water. Free water in-
gested into the compressor causes damage to in-
Since water vapor with chemical content cor-
rodes steel piping, precautions must be taken to
protect materials from corrosion. Galvanizing,
applying protective coatings, or using plastic or
stainless steel piping for air intakes are some
suggested methods to retard or prevent corrosion.
Also be sure to install intakes in a manner that
SPECIFIC AIR QUALITY
The diverse uses of air are accompanied by
specific air quality requirements. These vary from
high purity requirements through the need to in-
troduce materials into a system to be carried along
with the air. This section will discuss these specific
air quality requirements.
Commercial compressed air is graded accord-
ing to its purity. The purest is grade A running
alphabetically to grade J, the least pure. The Com-
pressed Gas Association has set guidelines for the
grading of commercial compressed gas. The ap-
plication of commercial compressed air is varied
and generally specified for each individual
installation by engineers. The full extent of the
quality requirements for commercial compressed
air applications can be located in the Compressed
Air Association publication Commodity Speci-
fication for Air, G-7.1 (ANSI 286.1-1973).
Breathing air must be of high quality for
obvious reasons. Federal Specification BB-A-1034
excludes rainfall, snow, or spray by applying a
(fig. 11-2) outlines the specific requirements for
Figure 11-2.Breathing air requirements, Federal Specification BB-A-1034A AM 1.