Figure 11-13.Typical water-cooled aftercooler.
Air Discharge Systems
Some discharge systems require special
consideration for the placement of auxiliary
equipment. All positive displacement compressors
require a relief valve on their discharge side to pro-
tect the equipment and piping upstream of the first
shutoff valve. Relief valves should be sized for at
least 125 percent of the maximum unit flow capacity
and should carry the American Society of
Mechanical Engineers (ASME) stamp, listing the
capacity and pressure setting of the valve.
Water and oil separators are required to
separate and free excess water from the discharge
air or gas. This is necessary to prevent corrosion,
deposit buildup, and water or oil buildup in the
piping or service. For example, water will cause rust
in piping, wash away lubricants, and plug nozzles.
Oil will contaminate many industrial processes and
may present an explosion hazard. The need for
water or oil separators will be determined by the end
use of the compressed air.
A centrifugal separator is illustrated in figure
11-14. Air is directed into this unit in a manner that
creates a swirling motion. Centrifugal force throws
the moisture particles against the wall where they
drain to the bottom.
Figure 11-14.Centrifugal-type moisture separator.