Yokogawa PK200 - Manual (Page 29)

IM 21B03D01-01E A-1
Appendix A. AIR SUPPLY SYSTEM
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 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 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 instru-
ments, considerations should be made, such as provi-
sion of water drain, filter, and downward pitch (1/100
or more) for piping.
F0A01.EPS
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 1 Example of Air Supply System (for Panel-Mounting Instrument)