Freeze drying connecting valves

Fig. 2.57. Laboratory freeze-drying plant. Microprocessor controlled, air-cooled compressor, condenser end temperature-53 °C, 3 kg of ice sublimed in 24 h. (a) Unit with 8 valve connections for 8 containers, condenser in an...

Figure 10-8. Equipment needed for lyophilization or freeze drying small samples, (a) The unit is cooled and evacnated by means of a self-contained refrigeration system and vacuum pump. Sample vessels are inserted into the rubber nozzles and the valve (little white knobs) opened for each nozzle that contains a vessel, (b, c) The units are evacuated by connecting them to a mechanical vacuum pump (connection indicated by arrows) and... 

Typical laboratory plants can be used for different purposes if equipped accordingly. One example is shown in Figure 28. In this unit, small product quantities can be freeze-dried in ampules, vials, or trays, and also flasks can be connected to it. The laboratory plant as shown in Figure 29 is equipped for multiple purposes Shelves can be cooled down to -35°C for freezing the product. A valve is installed between chamber and condenser. Thus it is possible to measure the sublimation surface temperature by BTM, to determine the end of main drying and to control secondary drying. The pressure can be controlled, the temperature of the shelves or the product can be recorded, and vials can be closed with stoppers. 

In pilot freeze-drying plants the connection between the chamber and the condenser has usually a diameter large enough for the transport of the water vapor. In large production plants this diameter has to be estimated. Theoretically the maximum flow density (g/h cm2) is achieved if the following conditions are met The diameter of the connection d has to be large, compared with its length /, / J, a smooth outlet from the chamber and a smooth inlet into the condenser with no obstacles in the connection (e.g., no valve plate) and s This flow density... 

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