Moisture Content Of Air Data; Moisture In Compressed Air - Honeywell AUTOMATIC CONTROL SI Edition Engineering Manual

MOISTURE CONTENT OF AIR DATA

See Psychrometric Chart Fundamentals section for use of
the psychrometric chart.

MOISTURE IN COMPRESSED AIR

Compressed air cannot hold as much moisture as air at
atmospheric pressure. When compressed, moisture often
condenses out leaving the air saturated with moisture.
Pneumatic systems require dry air to prevent problems with
–15 –10
Fig. 7. Moisture in Compressed Air Versus Temperature and Pressure.
ENGINEERING MANUAL OF AUTOMATIC CONTROL
-5 0 5 10
COMPRESSED AIR TEMPERATURE, ˚C
actuators or filters or restrictions in controllers. Figure 7 is used
to determine the maximum water vapor content of compressed
air at various temperatures and pressures.
EXAMPLE:
Assume ambient conditions are 25 C and 80 percent rh.
The air is compressed and stored in a tank at 310 kPa and
30 C.
Air is delivered to the controls at 240 kPa.
15 20 25 30
479
GENERAL ENGINEERING DATA
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
35 40 45
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