FREEZE DRYING & COLD TRAPPING

Vacuum freeze drying is a method of preserving a wide variety of products with minimal loss of their original physical qualities. This is achieved by converting the water contained in a product directly from ice to vapour.

Typical products suitable for freeze drying are:

• Fruit
• Flowers
• Fish
• Seafood
• Vegetables
• Meat A wide variety of health foods

The process has also been used by libraries to preserve and restore moisture damaged books and documents, and by pharmaceutical companies to prepare drugs.

A wide variety of freeze dryers are available, from small laboratory models to large industrial units that handle 1000kg per cycle. Javac New Zealand are also agents for the internationally known Telstar and Cuddon brands.

Javac New Zealand are pleased to announce the arrival of the first in a line of water vapour trapping products designed and manufactured from our factory in Auckland. The FDS Trap-Eze® -50ºC Refrigerated Cold Trap.

The FDS Trap-Eze® has been designed to maximise flexibility of use by incorporating pipework fittings (KF10/16/25, hose fitting, or up to 1” BSP connector) in the clear acrylic trap cover using a conventional trapping flow and return configuration. This means the unit can be used in-line before an oil sealed vacuum pump in many applications including freeze drying, concentrating, degassing, and many other operations. During 2004, a -85ºC two stage version will become available.

The FDS Trap-Eze® utilises a stainless steel trap collector of four and six litres depending on model, a temperature indicator, and CFC free refrigeration system. A Teflon coated version is also available where solvents, chemical, or organic vapours are present.

For those who are amazed at how easy it is to destroy expensive vacuum pumping equipment it is obvious that any products that do not reach the pump cannot cause a problem. This common place truth is all too often overlooked. Water at any vacuum pressure from atmospheric to 33mbar, and water, solvent, chemical, or organic vapours above 1mbar are most often pumped at pressures creating large quantities of vapour. The condensation of these vapours before they reach the pump offers two important benefits:

1. Additional protection provided to the pump assists the lubrication of bearing surfaces during severe processes.
2. The inlet condenser produces clean recovered liquids.

At pressures below 1mbar, the pump usually has to deal with high boiling point vapours, i.e. vapours of high relative molecular weight. With the exemption of a very small quantity of water vapour and even with gas ballasting, vapours are usually not expelled from the pump. It is highly recommended for these, they are condensed in a cold trap before they enter the pump. Typical cold traps are either low temperature refrigerated types or the more conventional liquid nitrogen based variety. In these situations some sludge and particulates tend to form in the oil regardless of all preventative measures. Adding to this tendency is the wide range of pumping applications a single pump will experience in a typical industrial, commercial, or laboratory setting.

Contact us now to discuss your vacuum pump needs.