Tech Zone

Understanding Cleanroom Performance Testing

The majority of the cleanroom owners have started demanding third party cleanroom performance testing to certify their cleanrooms to hide errors and presentation of false documents. This practice not only helps owners to cross verify the system's performance but also in preparation and presentation of documents for regulatory compliance. Bipin Patil, Founder, Aerience, Institute of Air Science and Contamination Control, Pune gives some pointers on cleanroom performance testing

the Cleanroom Performance Testing must be performed for certification of cleanroom to ensure that it complies with all the cleanroom acceptance criteria. Cleanroom Performance Testing (CPT), this term and trend is widely accepted in pharmaceutical and biotech industries internationally but is yet to be accepted in India. One should understand that CPT is a part of system validation. In the current practices, most of the cleanroom owners or HVAC (heating, ventilating, and air conditioning) installation contractor call local parties and carry out individual tests called Validation. Now the trend has changed and majority of the cleanroom owners have started demanding third party cleanroom performance testing to certify their cleanrooms to hide errors and presentation of false documents. This practice not only helps owners to cross verify the system performance but also in preparation and presentation of documents for regulatory compliance. Abroad there are many companies that provide the CPT services and they are usually accredited by NEBB / S2C2 / AABC etc. These accredited companies have the sophisticated and calibrated instruments to perform the testing. In additional, they have at least one qualified supervisor who conducts and witness CPT in accordance to the international recognised standard and recommended practices.

Today's need is to create awareness among the Indian Cleanroom Owners about CPT and also create certified CPT firms. In addition, it is always recommended that the CPT firm must have the knowledge of HVAC Testing, Adjusting and Balancing (TAB). This will certainly help Cleanroom owners to tune HVAC system to its optimum level for energy savings.

Cleanroom Performance Testing and Certification

All Cleanroom performance tests are mostly based on the following internationally accepted standards and recommended practices:

These standards and recommended practices assist in the initial formulation of the guidelines and parameters under which the Cleanroom facility can be certified and qualified. However, deviations are normally made and incorporated in the test procedures, specifications and acceptance criteria by the builder and the owner based on specific final product/process requirement. Most of the acceptance criteria are based on the mutual agreement between the builder and the owner, with some input and recommendations from the testing agency. The independent testing firm can usually advise appropriate testing procedures based on the type of Cleanroom facility being built. A good practice is to involve independent testing firm right from the start when the test procedures, specifications and acceptance criteria for the various parameters are being worked out. The independent testing firm serves as a check, a referee or a moderator between the builder and the owner. Having defined the need for CPT, the actual type of tests to be carried often depends on the type of cleanroom design and the user's specified requirement (usually from the product/process consideration)

Cleanroom types

A Unidirectional Airflow Cleanroom is one in which the filtered air entering the room makes a single pass through the work area in a parallel-flow pattern, with a minimum of turbulent flow areas. Unidirectional airflow rooms typically have high efficiency particulate air (HEPA) or ultra low particulate air (ULPA) filter coverage of 80 percent or more of the ceiling (vertical flow) or one wall (horizontal flow). In a non-unidirectional airflow cleanroom, the filtered air entering the room or passing through the work zone is characterised by non uniform velocity or turbulent flow. Such rooms exhibit non uniform, random airflow pattern throughout the enclosure. A mixed airflow cleanroom is a hybrid cleanroom containing both unidirectional and non-unidirectional types of airflow within the same enclosure.

Choice of Tests

The choice of tests for Cleanroom certification may be based on factors such as the design of the Cleanroom and/or its operational status, and the required level of certification. The tests can also be classified as primary or secondary. Primary tests are related to airborne particulate cleanliness classes as required by ISO 14644. A thorough operation performance evaluation employing these tests will assist in identifying the current cleanliness classification. These tests deal with airflow volume and uniformity, airflow velocity and uniformity, filter installation leaks, airborne particle count cleanliness classification and room pressurisation tests

Secondary tests are user optional and relate to particle and air movement and other ancillary cleanroom systems. They are tests dealing with airflow direction and visualisation (parallelism test), enclosure integrity, recovery tests, particle fallout, lighting level and uniformity, sound level, vibration level, temperature uniformity tests, humidity uniformity, electrostatic tests, Conductivity Tests and Electromagnetic Interference (EMI) Test.

Responsibilities

The successful completion and final certification of any cleanroom project depends upon an understanding and a commitment by everyone involved in the project. Quality assurance and quality control procedures established and followed throughout the construction phase of the project are as important to the final result as the components selected for use in the cleanroom and cannot be overstated. It is important to verify that all aspects of the cleanroom system, which contribute to its operational integrity, are complete and functioning before performing CPT.

Checklist

1. All the systems, sub-systems, and system components qualifies the installation. A fully verified installation that complies with the documented designs.

2. Air Handling System is commissioned following design qualification and user requirements and specifications. components of the air handling unit (AHU) like fan performance, (speed, pressure and flow), coil performance (fluid flows, pressure drops, capacity evaluation), pressure drop (across each components), electrical measurements and safety checks, available external static, evaluation of reserve capacity.must be thoroughly checked before proceeding to CPT. The disqualification of the above tests may result in to failure of some of the primary tests and secondary tests. The evaluation of reserve capacity of AHU is the most neglected subject in the current practices. The purpose of finding the air handling unit reserve capacity is to determine the amount of excess design capacity available in the AHU. The tuning of AHU as per the requirement helps in energy savings.

3. Duct Leakage Test: This is a very important test to be carried out confirming applicable seal class and leakage class. The leakages in the ducting are a direct energy loss and which cannot be recovered once ducting is installed and covered with insulation. In the cleanroom HVAC, loss of 1000 cfm cool air (through duct leakages) consumes 5-8 tons of refrigeration capacity, this result in to huge energy wastage. One must remember that one kilowatt savings is equivalent to saving of Rs 43,800.00 (at Rs 5.00 per kW/hr). Disqualification of duct leakage test may result in failure of some of the primary and secondary tests.

4. HVAC Testing Adjusting and Balancing (TAB) of all the systems, sub-systems, and system components are accomplished and reported.

5. Installation of clean filters, all diffusers and grilles properly installed.

6. Control components calibrated and operational, etc.

7. Standard Operating Procedures (SOP's) for each test are written and accepted by the cleanroom owner. Most of the times, in spite of selection of right test instruments; the test readings fail due to inadequate knowledge of handling test instruments / operation / limitations and SOP's.

If acceptable performance cannot be achieved because of design or system deficiencies, the test data must be documented in writing and distributed to the appropriate parties for resolution. Likewise, if certain tests cannot be performed due to improper installation of equipment or if system components have not yet been installed, this must also be documented in writing and distributed to the appropriate parties for resolution before CPT can begin.

The author is founder, Aerience, Institute of Air Science and Contamination Control, Pune