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 Section 2.
COMPRESSED AIR DISTRIBUTION METHODS
1 TYPES OF AIR DISTRIBUTION SYSTEMS. Compressed air is delivered to
consumers by either aboveground or underground piping systems. In many
instances, however, life cycle economics have found that small air compressors
at the source are more feasible than a compressed air distribution system.
2 DISTRIBUTION ROUTE. The minimum distance between the central compressor
plant and the consumers is the preferred routing for a compressed air
d i s t r i b u t i o n system; h o w e v e r , as with heat distribution systems, other factors
a f f e c t the final selection of a route. T h e s e factors include the following
i terns:
C h a r a c t e r i s t i c s of the location
Future expansion
Basements or crawl spaces available for piping
Aboveground obstructions such as rivers or roads
Underground obstructions such as piping or rock
S o i l Corrosivity
2.1 Secondary Systems. Generally, a separate system supplies each air
s e r v i c e ; however, economic considerations may justify installing additional
compressors to supply air to minor branch systems.
3 SELECTION OF ABOVEGROUND OR UNDERGROUND DISTRIBUTION SYSTEMS. The decision
whether to use aboveground or underground piping shall be based on the life
cycle economics. The advantages of each system are as follows:
Above-ground
Underground
L o w e r first cost
L e s s vulnerable target
Less maintenance
L e s s obstruction to
E a s y detection of failure
a b o v e g r o u n d traffic
Higher continuous operating
Less unsightly
Freeze protected when buried
efficiency
L o n g e r life
3 . 1 Other Factors. The following considerations may have an important
influence on the final decision of which system to employ.
Permanent versus temporary use
Existence of a high water table
Degree of hazard (for example, the potential danger that overhead
piping may cause to aircraft operations)
Annual ownership, operation, and maintenance costs
4 ABOVEGROUND DISTRIBUTION SYSTEM. An economic analysis will, in most
instances, demonstrate the advantages of an aboveground system. Other
requirements, such as temporary use or certain operating and local
r e s t r i c t i o n s , may dictate their use. Aboveground systems are less costly to
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