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  • Writer's pictureBona House Materials

7 basic items to be tested in clean rooms

Updated: May 22, 2023

Qualified third-party clean room testing institutions generally require comprehensive cleanness-related testing capabilities, including GMP pharma workshops, electronic dust-free workshops, food and drug packaging materials workshops, sterile medical equipment workshops, hospital clean operating rooms, biological universal laboratories, health food GMP workshops, cosmetics/disinfectants workshops, animal laboratories, veterinary drug GMP workshops, drinking barreled water workshops, and other clean rooms. The clean workshop provides professional technical services such as third-party testing, debugging, and consulting.

GMP pharma workshops

The scope of clean room testing generally includes: clean room environmental grade assessment, engineering acceptance testing, including food, health products, cosmetics, bottled water, milk production workshops, electronic product production workshops, GMP workshops, hospital operating rooms, animal laboratories, bio safety laboratories, bio safety cabinets, ultra-clean workbenches, dust-free workshops, sterile workshops, etc.

Test items: wind speed, air volume, ventilation frequency, temperature and humidity, pressure difference, suspended particles, floating bacteria, settling bacteria, noise, illuminance etc. For details, please refer to relevant standards for clean room testing.

1、 Wind speed, air volume, ventilation rate

The cleanliness of clean rooms and clean areas is mainly achieved by feeding sufficient clean air to displace and dilute the particulate pollutants generated in the room. Therefore, it is necessary to measure the air supply volume, average wind speed, air supply uniformity, air flow direction, and flow pattern of a clean room or clean facility.

Unidirectional flow mainly relies on clean air flow to push and displace polluted air inside the room and area to maintain the cleanliness of the room and area. Therefore, the wind speed and uniformity of its air supply section are important parameters that affect cleanliness. Higher and more uniform cross-sectional wind speeds can quickly and effectively remove pollutants generated during indoor processes, so they are the main detection items of concern.

Non unidirectional flow mainly relies on incoming clean air to dilute and dilute indoor and regional pollutants to maintain their cleanliness. Therefore, the greater the number of air changes, the more reasonable the airflow pattern, the more significant the dilution effect, and the corresponding improvement in cleanliness. Therefore, the air supply volume and corresponding air change times of non-single-phase flow clean rooms and clean areas are the main air flow testing items of concern.

To obtain repeatable readings, record the time average of the wind speed at each measurement point.

Air exchange rate: calculated by dividing the total air volume of the clean room by the volume of the clean room.

2、 Temperature and humidity

The measurement of temperature and humidity in a clean room or clean facility is usually divided into two levels: general testing and comprehensive testing.

The first level is applicable to the completion acceptance test in the empty state, and the second level is applicable to the static or dynamic comprehensive performance test. This type of test is suitable for occasions where temperature and humidity performance requirements are relatively strict.

This test is performed after the airflow uniformity test and after the air-conditioning system is adjusted. At the time of this test, the air conditioning system was fully operational and all conditions were stable. At least one humidity sensor is provided in each humidity control area, and sufficient stabilization time is allowed for the sensor. The measurement should be suitable for the purpose of actual use. The measurement should not be started until the sensor is stable, and the measurement time should not be less than 5 minutes.

clean-room-cosmetics-disinfectants- workshops- animal- laboratories

The purpose of this test is to verify the ability to maintain a specified pressure difference between the completed facility and the surrounding environment, as well as between spaces within the facility. This test applies to all three occupancy states. This test needs to be carried out regularly.

The pressure difference test should be conducted from high pressure to low pressure, starting from the interior room farthest from the outside on the plane layout, and sequentially outward with all doors closed; For clean rooms (areas) with holes connected at different levels and adjacent to each other, there should be a reasonable airflow direction at the opening.

3、 Differential pressure detection requirements:

1) The measurement of static pressure difference requires that all doors in the clean area be closed.

2) On the clean plane, the cleanliness shall be sequentially measured from high to low, until it reaches the room directly leading to the outside.

3) The measuring pipe orifice can be located anywhere in the room without the influence of airflow, and the measuring pipe orifice surface is parallel to the airflow flow line.

4) The measured and recorded data should be accurate to 1.0 Pa.

  • Differential pressure detection steps:

1) Close all the doors first.

2) Use a micro differential pressure gauge to measure the pressure difference between clean rooms, between clean room corridors, and between corridors and the outside world.

3) Record all data.

  • Differential pressure standard requirements

Determine whether to maintain the positive or negative pressure value of the clean room under test according to the clean room design or process requirements.

1) The static pressure difference between clean rooms or clean areas of different levels and non-clean rooms (areas) should not be less than 5 Pa.

2) The static pressure difference between the clean room (area) and the outdoor should not be less than 10 Pa.

3) For unidirectional flow clean rooms with an air cleanliness level higher than Level 5 (Level 100), when opening the door, the dust concentration on the indoor working surface 0.6 m inside the door should not be greater than the dust concentration limit of the corresponding level.

4) If the requirements of the above standards are not met, the fresh air volume and exhaust air volume should be readjusted until they are qualified.

4、 Suspended particle

A. Indoor testers must wear clean clothing, not more than 2 people, be located on the downwind side of the test point, away from the test point, and remain stationary. When performing point change operations, the action should be light and personnel interference with indoor cleanliness should be reduced.

B. The equipment should be used within the calibration period.

C. Equipment "reset" before and after testing

In the unidirectional flow area, the selected sampling probe should be close to isokinetic sampling, and the deviation between the wind speed entering the sampling probe and the wind speed of the sampled air should not exceed 20%. If this is not possible, align the sampling port with the main direction of the airflow. For non-unidirectional flow sampling points, the sampling port should be vertically upward.

E. The connecting pipe from the sampling port to the particle counter sensor should be as short as possible.


The sampling point is generally about 0.8-1.2 m from the ground, and it should be uniformly and scientifically distributed, and avoid the return air vent. For any small clean room or local air purification area, the number of sampling points shall not be less than 2, and the total sampling number can be obtained by dividing the area by 2 roots. The minimum number of sampling points corresponds to the number of suspended particle sampling points. The location of the measurement points in the work area is about 0.8-1.2 m from the ground, and the location of the measurement points at the air supply outlet is about 30 cm from the air supply surface. Additional measurement points can be added at key equipment or key work activity areas, and each sampling point is typically sampled once.

After all sampling is completed, place the culture dish in a constant temperature incubator for cultivation for not less than 48 hours. Each batch of culture media should have a control experiment to check whether the culture media is contaminated.

5、 Sedimentation bacteria

The measuring point in the working area is about 0.8-1.2 m above the ground. Place the prepared culture dish at the sampling point, open the cover of the culture dish, expose it to the specified time, and then cover the culture dish. Place the culture dish in a constant temperature incubator for cultivation for not less than 48 hours. Each batch of culture medium should have a control experiment to check whether the culture medium is contaminated.

6、 Noise

The measurement height is about 1.2 meters from the ground, and if the clean room area is less than 15 square meters, only 1 point in the center of the room can be measured; If the area is over 15 square meters, four additional diagonal points should be measured, one meter away from each side wall, with the measurement points facing each corner.

7、 Illuminance

The plane of the measuring points is about 0.8 m from the ground, and the points are arranged at a spacing of 2 m. The measuring points for rooms within 30 m2 are 0.5 m from the side wall, and the measuring points for rooms exceeding 30 m2 are 1 m from the wall.

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