Labconco FreeZone and FreeZone Plus 6, 12 and 18 Liter Freeze Dry Systems 79600 Series - Manual (Page 53)

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Chapter 7: Troubleshooting
Product Service Domestic 1-800-522-7658, International 816-333-8811
Refrigeration Module Operation
Under a no-load condition, the FreeZone Single Stage Freeze Dry
System can achieve a collector temperature of -50°C or lower
when the system is under vacuum, within 30 minutes when the
vacuum pump is running, depending on ambient temperature and
humidity. Cascade Freeze Dry Systems will achieve -84°C within
30 minutes.
Cascade Systems (those that operate @ -84°) 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
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 soak 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 competent refrigeration
technician or through an authorized Labconco service agency.