Positive pressure drying chambers

The core of a freeze drying plant (Fig. 2.61) consists of a drying chamber and a set of vacuum pumps. The pump should not be overexposed to water vapour, which possesses a very large volume in the low pressure range, and a cold trap is, therefore, always inserted before the pump - a so-called ice-condenser . The material to be dried is positioned on special trays which are put onto heater plates. These heater... 

The UC Riverside facility consists of dual 90 m chambers attached to a movable frame that is slowly lowered to maintain a slightly positive differential pressure. The chambers are located within a large, temperature controlled refrigeration container that is continually flushed with purified dry air. Two light somces are available a 200 kW argon arc lamp and two banks of 40 each 72 W 1.22 m fluorescent blacklamps. The temperature and humidity within the chamber can be accurately controlled (See Carter et al, 2005 for more detail). Advantages of the indoor reactor include temperature (recall from equation 2 the... 

The process used for sterilization by dry heat should include air circulation within the chamber and the maintenance of a positive pressure to prevent the entry of non-steriie air. If air is supplied, it should be passed through a microorganism-retaining filter. Where this process of sterilization by dry heat is also intended to remove pyrogens, challenge tests using endotoxins would be required as part of the validation. 

Figure 9.21 shows the direction of gas flows in a typical labyrinth seal. The number of chambers shown here is approximately the minimum a real unit may be more sophisticated than the one shown. Dry air (or nitrogen) enters the outermost chambers at a positive pressure maintained above that of the inboard seal on the compressor suction by a differential pressure control valve. Flow is then either to atmosphere or into the... 

If the product has to be kept and loaded at, for example, 5°C, the shelves at 5°C will freeze some water out of the atmospheric air, depending on its rh. At 5°C and 60% rh2, pHjO Smbar, the freezing of water will be limited to 7 g/m of chamber volume. These data can be reduced by running a positive pressure of dry nitrogen in the plant. 

The volume of a dry box (a closed chamber with dry nitrogen flowing through it) is 2.0 m. The dry box is maintained at a slight positive gauge pressure of 10 cm H2O and room temperature (25 C). If the contents of the box are to be replaced every five minutes, calculate the required mass flow rate of nitrogen in g/min by (a) direct solution of the ideal gas equation of state and (b) conversion from standard conditions. 

These sources are particularly suitable for the analysis of mixtures of nonvolatile and relatively polar molecules. They get rid of aqueous buffered solvents by using a drying gas and some heat. These ionisation chambers also make the transition from atmospheric to very low pressure an easy one. ESI and APCI offer soft ionisation, resulting in little or no fragmentation. They yield simple spectra where the principal peak usually corresponds to the pseudo-molecular ion (+H or +Na), making the molecular weight easy to derive. Both can be used in negative or positive mode. 

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