Process temperature controls

Temperature control is also important where microbial quality of the product is a concern. The processing of topical products at higher temperatures can destroy some of the objectionable microorganisms that may be present. However, elevated temperatures may also promote incubation of microorganisms. 

Temperature uniformity within a mixer should be controlled. In addressing temperature uniformity, one should consider the complex interaction among vat size, mixer speed, blade design, viscosity of contents, and rate of heat transfer. Where temperature control is critical, use of recording thermometers to continuously monitor and document temperature measurements is preferred to frequent manual checks. Where temperature control is not critical, it may be adequate to manually monitor and document temperatures periodically by use of handheld thermometers. 

It is current good manufacturing practice for a manufacturer to establish and follow written standard operating procedures to clean production equipment in a manner that precludes contamination of current and future batches. This is especially critical where contamination may present direct safety concerns, as with a potent drug such as a steroid (e.g., cortisone, and estrogen), antibiotic, or sulfa drug, where there are hypersensitivity concerns. 

The insolubility of some excipients and active substances used in the manufacture of topical products makes some equipment, such as mixing vessels, pipes, and plastic hoses, difficult to clean. Often piping and transfer lines are inaccessible to direct physical cleaning. Some firms address this problem by dedicating lines and hoses to specific products or product classes. 

It is therefore important that the following considerations be adequately addressed in a cleaning validation protocol and in the procedures that are established for production batches. 

The heat of reaction for the hydrolysis of epichlorohydrin was determined to be -17.6 kcal/mol by DSC measurement. With a value of this magnitude, the uncon- 

Based upon the complete model, the simulated behavior of the HKR reaction in a 50 L glass-lined vessel is shown for the following temperature control scenario (Fig. 25). Water flow-rate is adjusted to obtain 5°C in the medium (T) with a constant temperature of -5°C in the jacket (Tw) during the initial period of the HKR. The jacket temperature is then gradually increased to compensate for the reduced heat output when near reaction completion. 

At an industrial scale, heat removal is performed preferably under conditions of constant coolant temperature and flow-rate. Under these conditions, the rate of water addition is the only means of maintaining the reaction temperature within the desired range. To compensate for the diminished heat output as the reaction proceeds, the water addition rate can be increased accordingly. Ultimately, the coolant temperature must also be gradually increased when close to completion in order to maintain the desired working temperature. This mode of temperature control was demonstrated on a 50 L scale, and the temperature and rate of water addition profiles for this experiment are plotted in Fig. 27. Reaction completion is attained in 9 hours (ee=99%) with a potential yield of epichlorohydrin of 47% (94% of theory). These results are consistent with those predicted by the kinetic model (see Tab. 9). 

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Building or process temperature control fails high... 

Processes for Paraffin Nitrations. Propane is thought to be the only paraffin that is commercially nitrated by vapor-phase processes. Temperature control is a primary factor in designing the reactor, and several approaches have been investigated. A spray mtrator in which liquid nunc acid is spiayed into hoi propane is used industiially. Relatively small-diameter tubular reactors, fluidized-bed reactors, and molten salt reactors have all been successfully used in laboratory units. 

Instead of pH control for regulation of the dyeing process temperature control can be more convenient [104],... 

Process temperatures. The process temperature control is less critical in the hydraulic process than in the pneumatic system. 

Cooling within a reactor is typically provided by a reflux condenser. Since polymerization is a highly exothermic process, temperature control is a safety concern as well as a product integrity issue. Temperatiue control is primarily... 

Temperature control of a batch reactor In a particular batch reaction process, temperature control is critical to the safe operation of the process, as excess heat resulting from control failure could cause a mnaway reaction. The reaction kinetics are such that insufficient time is available for an operator to respond to a high-temperature alarm. It was also determined that any actions initiated by a high-temperature SIF would be inadequate to prevent an overpressure demand on the mpture disk due to the response time of the sensor. 

WATER-SOFTENER SELECTION AND ANALYSIS 19.20 COMPLETE DEIONIZATION OF WATER 19.22 COOLING-POND SIZE FOR A KNOWN HEAT LOAD 19.24 PROCESS TEMPERATURE-CONTROL ANALYSIS 19.26 CONTROL-VALVE SELECTION FOR PROCESS CONTROL 19.27 CONTROL-VALVE CHARACTERISTICS AND RANGEABILITY 19.29 CAVITATION, SUBCRITICAL, AND CRITICAL-FLOW CONSIDERATIONS IN CONTROLLER SELECTION 19.30 INDIRECT DRYING OF SOLIDS 19.34 VACUUM DRYING OF SOLIDS 19.36 ESTIMATING THERMODYNAMIC AND TRANSPORT PROPERTIES OF WATER 19.37... 

The shelf life of mixed compounds depends primarily upon the choice of curative, but is also very dependent upon the process temperature control and storage... 

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