Design controls

Safety is a critical aspect in the design of phenol plants. Oxidation of cumene to CHP occurs at conditions close to the flammable limits. Furthermore, the CHP is a potentially unstable material which can violendy decompose under certain conditions. Thus, phenol plants must be carefully designed and provided with weU-designed control and safety systems. 

Bioprocess Control An industrial fermenter is a fairly sophisticated device with control of temperature, aeration rate, and perhaps pH, concentration of dissolved oxygen, or some nutrient concentration. There has been a strong trend to automated data collection and analysis. Analog control is stiU very common, but when a computer is available for on-line data collec tion, it makes sense to use it for control as well. More elaborate measurements are performed with research bioreactors, but each new electrode or assay adds more work, additional costs, and potential headaches. Most of the functional relationships in biotechnology are nonlinear, but this may not hinder control when bioprocess operate over a narrow range of conditions. Furthermore, process control is far advanced beyond the days when the main tools for designing control systems were intended for linear systems. 

Model Development PreHminary modeling of the unit should be done during the familiarization stage. Interactions between database uncertainties and parameter estimates and between measurement errors and parameter estimates coiJd lead to erroneous parameter estimates. Attempting to develop parameter estimates when the model is systematically in error will lead to systematic error in the parameter estimates. Systematic errors in models arise from not properly accounting for the fundamentals and for the equipment boundaries. Consequently, the resultant model does not properly represent the unit and is unusable for design, control, and optimization. Cropley (1987) describes the erroneous parameter estimates obtained from a reactor study when the fundamental mechanism was not properly described within the model. 

Design control room to withstand blast overpressure... 

As a result of these poorly designed control systems, users experience significant operational problems, including machine and process shutdowns. As with any process plant, the first objective is to achieve reliable production from the FCCU. Only with reliable production will operators start optimizing the unit. Users, therefore, are not using the... 

Conduct work in designated controlled areas (e.g. in UK these are areas in which instantaneous dose rates >7.5 pSv/hour occur, or where employees may exceed 6 mSv annual dose limit, or where air concentration or surface contamination exceeds specified levels). 

Design control strategy for acceptable systems in order to handle different situations (seasonal, process variations). 

If you subcontract design, you must be able to demonstrate you have the appropriate capability to ensure your subcontractor meets the design control requirements of ISO/TS 16949. 

Is product design controlled in accordance with documented procedures ... 

Do the design controls ensure that design inputs are documented and reflect customer needs and expectations ... 

The standard requires product safety to be addressed in the supplier s design control and process control policies and practices with special attention to due care and means to minimize potential risks to employees, customers, users, and the environment. 

The standard doesn t require a procedure for Management Review and while it does require procedures for Design Control it does not specify that a Design Review Procedure is required. The phrases consistent with and in accordance with have the same meaning as both imply compatibility and agreement. If you restrict yourself to a literal interpretation of the standard, you need produce no more than 43 documented procedures - possibly less if some aspects do not apply to your business. You can combine several procedures in one document, the size of which depends on the complexity of your business. The more complex the business the greater the number of quality system documents. The more variations in the ways that work is executed, the larger the quality system will need to be. If you have a small business and only one way of carry-... 

This is a very sensible requirement and should have been included in ISO 9001 (see Part 2 Chapter 9). However, it should have been placed either under the heading Design control or under Process control, since the feasibility review in this context is not concerned with the feasibility of the project before commencing design but the feasibility of manufacturing the product following completion of design. 

Figure 4.1 Clause relationships with the design control element...

This general requirement for procedures introduces uncertainty into what particular procedures are actually required. The standard does not require the design control procedures to address each requirement of this clause but were they not to, you would need to demonstrate that the absence of such procedures had no adverse affect on the quality of design. 

This requirement appears low down in the list of requirements and should ideally have been the first requirement that the standard addressed under design control. Until you have a design input you cannot carry out your design and development planning. 

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