Clean room testing

Clean room test cleanliness test

First, clean room cleanliness instructions

Cleanliness testing is the core of clean room performance testing. Airflow testing, stress testing, and leak testing are only to confirm that the clean room is not affected by external influences. Therefore, the cleanliness tests are all passed in the above tests. after that. After the cleanliness test is completed, the performance factors related to the dust fall are tested. Other tests have little effect on the cleanliness, or belong to other environmental tests.

Second, clean room cleanliness testing equipment

The cleanliness test uses a particle counter. The instrument must be calibrated and still within the validity period. A qualified calibration document must be attached to the report. The particle counter has different specifications. The common one is the flow rate of 1cfm. The small particle size of Zui can be measured to 0.3mm or 0.1mm. The unit is mostly cubic inches. As for which equipment should be used, it depends on the owner's specifications. Generally, in the industrial world, the particle counter is selected in the following manner. Class 1000 or higher: 0.5μm Class 100 : 0.3μm , 0.5um Class 1 to Class 10 : 0.1μm If the particle size range required by the owner exceeds the range of a single particle counter, two particle counters should be used. At present, there is a rare particle counter in the market, so if the cleanliness of the clean room is based on ISO, the result should be converted. The unit conversion does not affect the calculation procedure of the upper limit.

Third, clean room cleanliness detection steps:

(1) It is determined that the test adjustment and balance of the air conditioning system have been completed, the wind speed and leakage test of the filter have been completed, and the damaged part has been repaired.

(2) Confirm the test position and the number of test points.

(3) Sampling time: The sampling time per point varies according to grade and particle size. If the sampling time is less than one minute, it is one minute.

(4) The test position should be evenly distributed in the clean room, avoiding the vicinity of the large number of particles, and the test instrument should be supported by the appropriate gantry.

(5) The number of measurement points is calculated by the formula (same as 209E).

Fourth, clean room cleanliness testing acceptance criteria:

There are two acceptance criteria for cleanliness. First, the average of the particle measurements at each point must be lower than the specified value. The second acceptance criteria for cleanliness is that if any compartment is to use the upper limit of reliability analysis, the analytical value must also be less than the specified value.

5. Wind speed and balance test for clean room testing

First, the purpose of the test

Airflow is the main factor controlling the cleanliness and temperature and humidity, and it also has some impact on noise. Therefore, the wind speed measurement is placed in the clean room test. The purpose of wind speed measurement is to confirm that the airflow sent by the filter meets the design specifications, and secondly to confirm the uniformity of the airflow. In some cases, due to site restrictions, the amount of indoor air exchange must also be converted by the wind speed multiplied by the exit area.

Second, single * direction type clean room, many are designed as vertical laminar flow, so the uniformity of wind speed is very important, only uniform vertical laminar flow, can effectively eliminate particulate pollution. Non-single * direction type clean room, because the concept of particle control is dilution, not immediately excluded, in general, the amount of air exchange is far more important than the wind speed. However, it should be noted that it is a filter wind speed measurement or a clean room indoor wind speed measurement.

Third, the use of instruments

The HEPA/ULPA filter used in the clean room is mostly controlled at a speed of 0.5 m/s, so the anemometer used must be of a low speed type. The filter wind speed measurement can use a single-point anemometer such as an electronic pressure gauge with a picotube and an anemometer. Multi-point anemometers such as the Shortridge Velgrid 16-point anemometer can also be used. Flange anemometers are usually not used in clean rooms due to their different ranges of use. Although the high temperature response of the anemometer (Hot Wire) is low, the accuracy is less than <0.5m/s at low speed, so it is not very suitable. Generally, the thermal reaction anemometer is commonly used by the Thermeister anemometer. The rotary anemometer is not suitable for low speed due to its own weight problem. Inspection and balance testing . Pressure loss is generated, so its shape is important, and the original hood should be used as much as possible. If it is necessary to make the cover yourself, pay attention to the smooth airflow and make a detailed comparison. The calibration of the hood is very important and must be corrected with the main unit to obtain an accurate correction value. Instruments that have passed the calibration and are still valid shall be used for inspection. Qualified calibration documents shall be attached before the formal inspection and when the report is submitted.