<Appendix A. Air Supply System>
A-1
IM 21B03D01-01E
Appendix A. Air Supply System
1. Overview
Pneumatic industrial instruments are one of the
most maintenance-free, highly reliable industrial
instrument systems and are in wide use. Such
features are fully demonstrated only when suitable
service conditions where the characteristics of
pneumatic instruments are sufficiently taken into
account are established.
One of such service conditions includes an air
supply system. Pneumatic instruments require
clean, dry air and thus, an aftercooler, filter, and
air drier are installed after a compressor to prevent
water, oil, and other contaminants from entering into
the instruments. Also, care should be exercised as
described below at service points.
2. Air Supply System
(1) Example of Panel-Mounting Instrument
When air is to be supplied to multiple instruments
it is recommended that two reducing valves are
used in parallel as shown in Figure A.1. Parallel
arrangement protects instruments from interference
even if one reducing valve is suspended due to
clogging. Also, use of a three-way cock as shown
in Figure A.1 allows any of air supply systems to
be separated for maintenance. Generally, both air
supply systems are used in parallel for operation.
To supply clean and dry air to instruments,
considerations should be made, such as provision
of water drain, filter, and downward pitch (1/100 or
more) for piping.
F0A01.ai
Air supply pipe for
instrument
Shut-off value
Slope approximately 10 mm
per meter length (1/100)
Drain valve
Clean dry air
supply
3-way cock
Air filter
Pressure gauge
Regulator
High
pressure
air
supply
Figure A.1 Example of Air Supply System (for Panel-Mounting Instrument)
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