Fluid transfer design

Some asceptic processes are developed initially in non-sterile facilities and need to be re-designed to produce a sterile product. Thus the type, size and material used for vessels, piping and tubing (particularly product contact surfaces), the selection of appropriate equipment for each unit process i.e. mixing, filtration, filling, etc., the use of disposable or re-usable equipment, the order of unit operations, the fluid transfer between unit operations and... 

On the one hand, the differential reactor with recycle permits kinetic measurements of high accuracy. On the other hand, a transfer equipment is required to recycle a fraction of the reaction mixture. This can be difficult when the pressure is high. For this purpose, a jet loop reactor was developed which is equipped with an ejector to recycle the fluid. The design of the jet loop reactor is described in Chapter 4.3.4. 

For the freezing of food, stainless-steel belt conveyors are used, which are cooled with a spray of cold heat transfer fluid. The design of such conveyors is difficult, since sealing of the moving belt between the heat transfer fluid and food can cause leaks and abrasion. 

In addition to the dissolution and identification tests, the ability of the system to perform an assay and a content uniformity determination has been demonstrated. Because there are no fluid transfers, the vessels can be sealed, eliminating the need for volume corrections or fluid replacements. Therefore, with a 12-vessel dissolution apparatus, it is possible to designate 10 of the vessels for the content uniformity test and to average the results from the 10 or 12 vessels for the assay determination. Typical data for a 12-hour controlled-release product are presented in Table 2. Excellent agreement between the fiber-optic- and HPLC-based measurements is evident. 

Some applications of cryogenic-fluid transfer require optimization of many aspects of transfer-system design. This study examines methods of transfer-line insulation, the problems of metal degassing, and line storage life. 

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