IEST-RP-CC006.3: Cleanroom Testing

The primary purpose of testing cleanrooms and clean areas is to determine their operational performance. The existing "IEST RP-CC006.3: Testing of Cleanrooms" provides a set of proven and standardized test procedures that can determine the performance of cleanrooms and clean areas. The test procedures are divided into two categories: preliminary tests and intermediate tests. Preliminary tests are closely related to the classification or verification of the cleanliness of airborne particles in cleanrooms. The test content includes the following parts: airflow volume, velocity and uniformity test; HEPA and ULPA filter installation test; airborne particle counting test; room pressurization test. Intermediate tests include other characteristics related to cleanrooms or clean areas. The specified acceptance scope consists of the following: visual airflow characterization test; light intensity and light uniformity test; noise level test; temperature and humidity uniformity test; vibration test. We may need to perform one or more operating states, that is, empty, static or operating state.

Performance Tes

In general,  for unidirectional cleanrooms, the following order is recommended: airflow volume or airflow velocity test; visual airflow characteristic test; room pressurization test.

Recommended Practices (RPs) are expected to assist planners, designers, manufacturers, and users in preparing detailed specifications for Cleanroom Testing to ensure that the cleanroom is operating as intended. Under the agreement, the user will select appropriate tests for their cleanroom and establish the acceptance limits necessary for the cleanroom's use. RPs may also be used to write in-house test procedures for dedicated Cleanrooms.

RPs also recommend test equipment for various test methods. If the type of cleanroom (i.e., unidirectional or non-unidirectional) affects the test method, then alternative test procedures may be used. For some test procedures, more than two tests, methods, or test equipment may be used so that they meet the requirements of the end user's concerns. When using alternative methods, the end user should be aware that the results obtained by different methods may not be consistent. In general, RPs do not provide acceptance limits, but only standard terms for determining appropriate limits. In addition, RPs do not fully include all tests that can be used to characterize cleanroom operating parameters, such as particle settling rate, airborne molecular contaminants, microorganisms, electrostatic discharge (ESD), recovery tests, and contamination leakage tests, as well as other tests not mentioned.

Basic Test

Airflow, velocity, and uniformity tests. These tests determine the velocity and uniformity of airflow in unidirectional cleanrooms and clean zones, as well as the velocity and uniformity of the airflow in cleanrooms. Tests typically require either velocity or volume, and can be derived from average velocity, average flow, or total flow. From total flow, the number of air changes can be determined.

HEPA and ULPA filter installation leak tests. These tests can be used to determine the integrity of a HEPA or ULPA filter system. This test is accomplished by introducing a test aerosol upstream of the HEPA or ULPA filter and performing an integrity scan downstream of the filter, including from the filter to the frame seal. This recommended practice references "IEST-RP-CC034: HEPA and ULPA filter leak testing", which describes this part of the test in detail. County airborne particle count test. This test can determine whether A CleanRoom in a completely empty, static, or operating state meets the detailed classification of specific air cleanliness in "ISO 14644-1:1999". In general, it refers to the test methods documented in ISO Standards. Room pressurization test. This test verifies the ability of the cleanroom to maintain a specified static pressure difference with the surrounding environment, including the space above and below the cleanroom. Generally, cleanrooms have a positive pressure, however, for certain applications that require leakage prevention, such as those involving toxic, biological or radioactive materials, negative pressure must be specified.

Intermediate test

Visual airflow characteristics test. The purpose of this test is to visually describe the main airflow direction (flow vector) at multiple locations and adjacent locations throughout the work area. This test verifies the cleanroom's ability to control the spread of airflow to determine the source of air contamination. There are two test methods provided here: streamline test and aerosol dispersion test. Illuminance and uniformity test. The purpose of this test is to verify whether the illumination and uniformity of light in the cleanroom meet the specified requirements. Noise level test. The purpose of this test is to measure the sound pressure levels generated by the mechanical and Electronic systems of the cleanroom and by the adjacent external areas to verify whether they meet the requirements of the end user.

Temperature and humidity uniformity test. The purpose of these tests is to determine if the air conditioner can maintain temperature and humidity (expressed as Relative humidity or dew point) within the specified range for a period of time specified by the end user. These test methods are divided into two levels, namely routine testing and comprehensive testing. Comprehensive testing requires profiling the cleanroom to determine uniformity, while routine testing only requires setting up a test location in each temperature control zone. Vibration Testing. The purpose of this test is to determine the vibration level of the cleanroom structure and its composition to verify whether the cleanroom meets the requirements of the end user.