Van Air Systems FR-1600 - Manual (Page 6)

PAGE 6
6.1 DESCRIPTION OF OPERATION
The Prep-40 is a portable skid mounted system consisting of a strainer,
pre-cooler, separator/prefilter, prefilter, heatless regenerative dryer and
an afterfilter. Wet warm air enters the pre-cooler where it is cooled to a
temperature approaching ambient. Water is condensed out during this
cooling process. The saturated air and the liquid water proceed to the
inlet of the separator/prefilter where the liquid water is removed. Then
the saturated air enters the coalescing filter where additional oil and liquid
water is removed. Then the air enters the heatless twin tower dryer where
it moves upward through the desiccant bed. The moisture is adsorbed
onto the surface of the desiccant. Dry air exits the heatless dryer and
passes through the general purpose particulate after-filter where residual
particulate is removed.
This package dryer will take saturated air at rated conditions and reduce
the mositure content to -40°F pressure dew point.
5.5 CONDITIONING THE DESICCANT BED
To condition the desiccant bed, the dryer system is operated without any
outlet flow while the towers regenerate with purge air.
Observe the dryer system for several cycles to make sure that it is op-
erating properly.
OPERATION SECTION 6
Operate the until NO desiccant dust is visible at the purge valves.
Then the mufflers can be installed.
IMPORTANT
The dryer system must be operated for several hours without
the mufflers after the towers have been filled with desiccant.
This will prevent the mufflers from becoming clogged.
FIGURE 5A PURGE MUFFLER INSTALLATION
5.3 SETTING THE CONTROL PRESSURE REGULATOR
The control pressure regulator is located in line with the control filter and
it is used to protect the pneumatic control components. This regulator
should be set at 100 PSIG.
CAUTION
DO NOT OPERATE THIS DRYER SYSTEM WITH
THE CONTROL AIR PRESSURE REGULATOR
ABOVE 100 PSIG TO PREVENT DAMAGE TO
THE PNEUMATIC CONTROLS.
Mufflers were shipped separately. They should NOT be installed until
the dryer system has been operated for several hours. From desic-
cant installation, some dust may be present in the desiccant towers.
Operating the dryer system with the mufflers installed immediately after
the towers have been filled with the desiccant or during initial start up
may cause the mufflers to clog.
6.2 HEATLESS DRYER PRINCIPLE OF OPERATION
The Heatless Regenerative Air Dryer utilizes the pressure swing principle
of operation. The desiccant bed in one tower dries the air stream while
the desiccant bed in the other tower is regenerated.
A purge of dry air is used for tower regeneration. It is taken from the
outlet of the dryer.
The dryer is equipped with a purge metering valve to allow the correct
amount of dry air to flow into the regenerating tower. The heat created
during adsorption of moisture in the drying tower is retained in the desiccant
bed and increases the moisture removal capacity of the purge air.
The timing cycle of the dryer is controlled by two 3-way pilot valves.
To achieve maximum performance from this dryer, it should be operated
continuously. Operating this dryer for single shift periods may result in
varied outlet dew point performance.
The dryer operation consists of four stages; REPRESSURIZATION,
CHANGEOVER/DEPRESSURIZATION, DRYING, and REGENERATION.
START UP SECTION 5
5.6 INSTALLING THE PURGE MUFFLERS
To reduce the sound level during purge and tower depressurization,
this dryer system was supplied with mufflers for installation on the
purge exhaust valves.
5.4 ADJUST THE REGULATOR & LUBRICATOR
The regulator and lubricator for the pre-cooler air motor must be properly
set to ensure trouble-free air motor operation.
The regulator is used to set the speed of the pre-cooler fan. The regulator
is factory set using a tachometer and a clean precooler core. See FIGURE
5C. As the core becomes dirty, a higher regulator pressure setting may
be required to maintain the fan speed.
Set the lubricator per FIGURE 5D.
FIGURE 5C FACTORY REGULATOR SETTING
DRYER
MODEL
FR-1600
SETTING
(PSIG)
30
FIGURE 5D LUBRICATOR SETTING
DRYER
MODEL
FR-1600
DROPS PER
MINUTE
1
FAN SPEED
(RPM)
1725
AIR USAGE
(SCFM)
25
At initial start up or after extended shutdowns (over one month), the dryer
system may take 24 to 48 hours of continuous operation for the bed to be
conditioned. Moisture that has accumulated on the desiccant bed should
be removed before the dryer system is placed on stream.
Once the moisture indicator on the dryer system turns blue, the desiccant
bed is ready. The Prep-40 dryer is now ready for operation.