Chapter 7: Troubleshooting
Product Service 816-333-8811 or 1-800-522-7658
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Refrigeration Module Operation
Under a no-load condition, FreeZone Plus Cascade Freeze Dry Systems
should achieve a collector temperature of –81°C or lower when the vacuum
pump is operating. If the collector temperature does not reach the design
temperature within 40 minutes, then the refrigeration module is not
functioning properly.
Cascade Systems (those that operate at -81°C) consist of two vapor-
compression refrigeration systems in series connected together via a heat
exchanger. Each system has a compressor, condenser, capillary tube
metering device and an evaporator. During the operation the evaporator of
the “high stage” system refrigerates the condenser of the “low stage” system.
This takes place in the heat exchanger. The low stage and high stage systems
are balanced by design, however, sometimes that balance can be disrupted
during operation and the unit will not function properly. If the unit is
overloaded, or if the unit is defrosted and restarted in a short time interval,
system unbalance is possible. If system unbalance occurs, turn the freeze
dryer off and allow the unit to stabilize at ambient temperature for 2 to 4
hours.
If any repairs are required on the refrigeration module, contact your local
laboratory supply dealer. If your laboratory supply dealer is unable to
provide assistance, please call Labconco. Repairs should only be undertaken
by a refrigeration technician or through an authorized Labconco service
agency.
