Effective change control system

An effective change control system must allow a firm to proactively evaluate proposed changes to a method before they are implemented. 

Associated project documentation used by other engineering disciplines is also essential, and it is important that an effective change control system is in place to communicate changes made to Engineering Lines Diagrams (ELDs/P IDs), I/O Schedules, and Process Descriptions. 

Conhrmation that change control systems have operated effectively... 

Reviewing the system by establishing appropriate accountability systems within the organization to monitor and report quality data and system status to management and assure that appropriate corrective and preventive actions are taken in response to quality problems using effective change control procedures and documented... 

Utility and HVAC systems are among the easiest to address with respect to revalidation. Their performance is evaluated on a near continuous basis through the collection and testing of samples taken from the system. This affords a direct and ongoing assessment of the system s acceptability for use. Coupled with effective change control, calibration, and preventive maintenance programs, the collected data from the system should support its continued use. The preparation of summary reports on results from the system on a monthly or quarterly basis precludes the need for further evaluation. 

Computer validation should not be undertaken unless fundamental validation controls have been fully understood and implemented within the pharmaceutical or healthcare company s organization. Here we allude to properly qualified personnel, effective document management and change control systems, internal audit procedures, methods of managing the deviations from standard practice thereby exposed, and a culture of continuous improvement (see Chapter 4 for more details). Senior management must not fall into the trap of assuming through complacency or idleness that these controls have been fully instituted In most firms there is usually much that still needs to be done in these areas. Let us examine these controls a little more closely. 

A formal change control system should be established to evaluate the potential effects of any changes on the quality of the herbal medicines, particu-larly content of the active ingredients. Scientific judgement should be used to determine which additional testing and validation studies are appropriate to justify a change in a validated process. 

Well-designed and engineered systems can rapidly become ineffective, inefficient, and/or hazardous without effective change controls. 

Some of these changes have resulted in the need for more effective foam control systems, whereas the soaps traditionally used have been largely replaced by other options. 

Open-Loop versus Closed-Loop Dynamics It is common in industry to manipulate coolant in a jacketed reacdor in order to control conditions in the reacdor itself. A simplified schematic diagram of such a reactor control system is shown in Fig. 8-2. Assume that the reacdor temperature is adjusted by a controller that increases the coolant flow in proportion to the difference between the desired reactor temperature and the temperature that is measured. The proportionality constant is K. If a small change in the temperature of the inlet stream occurs, then depending on the value or K, one might observe the reactor temperature responses shown in Fig. 8-3. The top plot shows the case for no control (K = 0), which is called the open loop, or the normal dynamic response of the process by itself. As increases, several effects can be noted. First, the reactor temperature responds faster and faster. Second, for the initial increases in K, the maximum deviation in the reactor temperature becomes smaller. Both of these effects are desirable so that disturbances from normal operation have... 

A cocurrent evaporator train with its controls is illustrated in Fig. 8-54. The control system applies equally well to countercurrent or mixed-feed evaporators, the princip difference being the tuning of the dynamic compensator/(t), which must be done in the field to minimize the short-term effects of changes in feed flow on product quality. Solid concentration in the product is usually measured as density feedback trim is applied by the AC adjusting slope m of the density function, which is the only term related to x. This recahbrates the system whenever x must move to a new set point. 

The traditional design method normally makes use of overall values even when resistance to transfer lies predominantly in the liquid phase. For example, the COg-NaOH system most commonly used for comparing the Kg< values of various tower packings is a liqiiid-phase-controlled system. When the liqiiid phase is controlling, extrapolation to different concentration ranges or operating conditions is not recommended since changes in the reaction mechanism can cause /cl to vary unexpectedly and the overall values do not explicitly show such effects. 

The new control systems must be monitored for effectiveness and your operations monitored to make sure you respond to any changes that bring your operations under the requirements of existing regulations and policies. The monitoring program is designed to determine the effectiveness of the controls. If these are found to be inadequate, they must be modified. 

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