Acceptance testing or qualification?

In any case, the specification provided by the user – e.g. in the form of a "User Requirements Specification" (URS) – is decisive for the criticality of the systems. In this specification, therefore, the product’s critical quality attributes (CQA) and the related critical process parameters (CPP) that have an influence on product quality must be defined (see Figure 3.J-2).

Figure 3.J-2 Levels of influence for critical parameters

In the process, the relevant measurable parameters must be defined with the permitted tolerances. This forms the basis for the qualification.

In addition to the systems subject to qualification, there are many other systems for which proper performance must also be ensured and proven. For this purpose, the required parameters are tested by qualified personnel within the scope of technical acceptance testing.

Deciding when to take which approach can be made, for example, by classification of the systems and definition of the critical components. The impact on the quality of the product can be used as a criterion for this classification. Two categories are usually distinguished:

• direct impact system and
• no impact system

Some guidelines also describe a third category; however, the boundaries are somewhat fluid:

• indirect impact system

Systems with direct impact are systems with direct product contact and/or critical components, the failure of which affects the product quality. These systems are subject to qualification on the basis of a URS. For the other systems, technical acceptance testing according to GEP (Good Engineering Practice) based on a general user specification is sufficient.

Examples of classification:

With a compressed air supply, a distinction must be made between compressed air in contact with the product (direct impact) on the one hand and technical compressed air (no impact) on the other (3.H Pharmaceutical gases):

• For compressed air in contact with the product, a qualification is required in addition to the technical acceptance testing, as it represents a potential contamination risk for the product (result of the risk assessment) and contains critical components (e.g. sterile filters).
• For utility-grade compressed air without direct impact technical acceptance testing according to the rules of Good Engineering Practice (GEP) is sufficient, since it cannot directly contact the product.

An AHU that supplies a filling plant such as in an isolator (the air is "in contact with the product") must therefore be evaluated differently from an AHU that supplies a room where a closed process is performed:

• In the air supply of the aseptic zone, the final HEPA air filter is the critical component that, together with the downstream air flow pattern, requires the unit to be classified as a system with direct impact.
• The ventilation components of the supply air and exhaust air system (fan, preliminary filter stages, etc.) have no direct impact and can also be described as an "indirect" system, whereby the HEPA filter represents the boundary.
• Air coolers and heaters can only be classified as critical if temperature and humidity have an influence on the product quality.

Examples of direct impact systems:

• Pharmaceutical gases for production purposes
• Purified water and clean steam for production purposes
• Air supply for aseptic sectors
• CIP/SIP systems (in some cases classified as indirect impact systems)
• Process monitoring
• Environmental monitoring (while here only those parameters are concerned which have a direct impact on a critical process parameter (CPP) or on product quality (CQA). Thus, temperature and humidity do not apply if only controlled for the comfort of the employees)

The terms “Commissioning and Qualification” (C&Q) are often used in this field to describe work performed to enable usage of technical equipment. “Commissioning” refers to the documented process of initiating operational start-up and hand-over of the plant or system to the user in sense of technical acceptance testing. It goes without saying that during the commissioning of an AHU it is necessary to perform measurements to document that the requirements are met within specified tolerances. These are the user-specific design requirements (e.g. those provided in the URS), such as maintaining air flow in the specified direction, upholding temperature, humidity, noise level and contaminant concentration targets. These are checked as part of the acceptance testing and the documented results may be used as part of the qualification – the same parameter does not need to be re-confirmed as part of different processes (acceptance testing and qualification).

This convention should prevent the “overqualification” of plants. Parameters which were tested during the technical acceptance testing but have no direct impact on production quality should not be included in the qualification documentation, or at least the parameters should be given sufficiently wide tolerance ranges. This serves to avoid unnecessary deviations which in the end are categorized as “not relevant to quality”.

Example for the delimitation of acceptance testing from qualification:

During acceptance testing the requirement placed by the user to maintain a relative air humidity both in summer and winter of 50% ±10% is to be tested. This specification serves to maintain the comfort of the employees in the defined cleanroom apparel and performing the defined activities.

• If the humidity is not classified as having an impact on the product quality the parameter does not need to be qualified and does not need to be included in the monitoring programme, or
• It is given a broader tolerance range, such as 30% to 70%.

Conclusion: Technical acceptance testing can be seen as a preliminary stage and supplement to qualification, since the same objectives are pursued in both procedures. The boundaries between technical acceptance and qualification are to be clearly defined on plans and functional diagrams.