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3.2.3 All MODELS - Determine if air control valves are operating and
sequencing correctly.
3.2.3.1 Inlet switching and purge/repressurization valves.
1) Tower pressure gauge of tower on-line should read line pressure. No
air should be leaking from purge/repressurization valve of the on-line
tower.
2) Tower pressure gauge of tower off-line should read below 2 psig while
tower is purging. If excessive purge air is exhausting during purge
cycle, inlet valve may have failed to close or a check valve may be
sticking.
3.2.3.2 Check valves
Check valve sticking will result in excessive air discharge through a muf-
fler. If excessive air is discharged through the muffler on the left, check
if valve 5a or 5d is sticking. If excessive air is discharged through the
muffler on the right, check if valve 5b or 5c is sticking.
3.3 Shut Down
3.3.1 Depressurize dryer
3.3.1.1 Open by-pass valve (if one is installed) and close inlet and
outlet isolation valves.
3.3.1.2 Run timer through a tower change cycle until pressure gauges
on both towers read 0 (test mode may be used to speed this
up).
3.3.2 De-energize dryer
Turn dryer off using on-off switch (indicating lights extinguished).
3.4 Loss of Power
Control valves are designed so that upon loss of power the air dryer
is capable of drying air until the desiccant exposed to the air flow is
saturated.
3.5 Verify that dryer is operating within design parameters
3.5.1 Maximum working pressure:
Refer to Serial Number Tag to determine maximum working pressure
of dryer.
WARNING
Do not operate dryer at pressures above the maximum pressure shown
on the tag.
3.5.2 Minimum working pressures: 100 psig (7 barg)
