Specifications

Dryer Operation
Dryer Operation
Compressed air saturated with water vapor passes through the inlet valve and flows upward through
the desiccant in tower “A”. Tower “A” is said to be “on line”. The activated alumina desiccant adsorbs
the water vapor in the compressed air and the pressure dew point is lowered to a minimum of –40°F.
The dried air then passes through a check valve assembly to the outlet piping and then to the factory
tools or equipment.
While the air is being dried in tower “A”, the desiccant in tower “B” that adsorbed moisture in the previ-
ous cycle is simultaneously regenerated. Tower “B” is “off line”. At the start of the regeneration cycle,
tower “B” is depressurized from the operating pressure to atmospheric pressure with a downward air
flow and passes through the purge valve and out the purge muffler. Regeneration continues with a
portion of the dry air from tower “A” passing through an orifice assembly and downward through
tower “B” out to atmosphere.
This process takes about ten minutes to complete, with the drying cycle using about five minutes to
provide the desired dew point. The regeneration cycle takes approximately 45 seconds less to allow for
repressurization before switchover. The complete operation therefore consists of two cycles, one for
drying and the other for regeneration. Required purge air is generally 15% of rated flow. As pressure
is a direct function of purge air, the higher the pressure, the lower the purge
.
NOTE: At Initial Start-Up, check the dryer operation for one or two cycles, especially at the time
of the tower shift. Verify that all systems are operating in their proper order and sequence.
If the dryer is not functioning properly, contact your Arrow Representative.
"On-Line"
Drying
REGENERATING FLOW
DRYING FLOW
"On-Line"
Drying
"Off-Line"
Regenerating
REGENERATING FLOW
DRYING FLOW
"Off-Line"
Regenerating
LEFT TOWER "A"
RIGHT TOWER "B"
LEFT TOWER "A"
RIGHT TOWER "B"
SLOWLY PRESSURIZE THE DRYER!
When the dryer reaches full operating pressure, check the system for air leaks. Soap test
all joints and fittings. To maintain desired dew point, any leaks detected must be fixed,
especially those on the outlet side of the dryer.
Energize electrical circuit by simply pressing the power on/off button.
The Power On LED will be illuminated when the dryer is in operation.
When the electrical circuit has been energized, the control circuit board will
start to operate and automatically initiate dryer operation. The timer is factory set,
so that no field adjustment is necessary.
Adjust purge adjustment valve so that the center purge pressure gauge reads appropriate
pressure (see specifications chart for purge pressure on page 2).
AFTER ALL PIPING AND ELECTRICAL CONNECTIONS ARE MADE, PROCEED AS FOLLOWS:
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