7 basic items that need to be tested in cleanroom

Testing items: air velocity and air volume, air exchange, temperature and humidity, differential pressure, suspended particles, planktonic bacteria, settled bacteria, noise, illumination and so on. Specifically, you can refer to the clean room testing standards.

The wind speed and air volume and the number of air changes

Clean room, clean area of the cleanliness is mainly by sending in a sufficient amount of clean air, in order to replace, dilute the indoor production of particulate contaminants to achieve. To this end, the determination of clean room or clean facilities air supply, average air velocity, air supply uniformity, airflow direction and flow type and other items is very necessary.

Unidirectional flow is mainly rely on clean airflow extrusion, replacement of indoor, area of contaminated air to maintain indoor, area of cleanliness. Therefore, its air supply section wind speed and uniformity is an important parameter affecting the cleanliness. Higher, more uniform cross-section wind speed can be faster, more effective exclusion of pollutants generated by indoor processes, so they are the main concern of the test program.

Non-unidirectional flow mainly relies on incoming clean air to dilute and dilute the pollutants in the room and area to maintain its cleanliness. Therefore, the greater the number of air exchanges, the airflow pattern is reasonable, the more significant dilution effect, cleanliness is also improved accordingly. Therefore, the volume of air supply and the corresponding number of air changes in non-single-phase flow clean rooms and clean zones are the main concern of the airflow test program.

In order to obtain repeatable readings, record the time average of the air velocity at each measurement point.

The number of air changes: according to the total air volume of the clean room divided by the volume of the clean room to obtain

Temperature and humidity

Clean room or clean facilities temperature, humidity measurement, usually divided into two grades: general testing and comprehensive testing. The first grade applies to the empty state of the completion of the acceptance test, the second grade applies to static or dynamic comprehensive performance test. This type of test is applicable to the temperature and humidity performance requirements are more stringent occasions.

This test is conducted after the airflow uniformity test and after the adjustment of the air conditioning system. When this test is performed, the air-conditioning system has been fully operated and the conditions have been stabilized. At least one humidity sensor is set up in each humidity control area, and the sensors are given sufficient time to stabilize. Measurements should be appropriate for the purpose for which they are to be used, and should be taken only after the sensors have stabilized, and for a period of not less than 5 minutes.

The purpose of this test is to verify the ability of the completed facility to maintain a specified pressure differential between the completed facility and its surroundings and between spaces within the facility. This test applies to all 3 occupancy states. Periodic performance of this test is required.

Differential pressure test should be in all the doors are closed under the condition, from high pressure to low pressure, from the plane layout and the farthest from the outside world in the room to start, in turn to the outside of the test; there are holes connected to different levels of adjacent clean room (area), the hole should be a reasonable airflow flow and so on.

The differential pressure test requirements

 1) the determination of static differential pressure requirements in the clean area of all the doors are closed.

 2) in the clean plane should be carried out in order from high to low cleanliness, has been detected to the room directly outside.

 3) Measurement of the mouth of the tube is located in the room without the influence of airflow anywhere, the measurement of the mouth of the tube surface parallel to the airflow line.

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

Differential pressure detection steps:

 1) Close all the doors first.

 2) Measure the differential pressure between clean rooms, between clean room corridors and between corridors and the outside world with a differential pressure meter.

 3) Record all data.

Differential pressure standard requirements

  According to the cleanroom design or process requirements to determine the maintenance of the measured cleanroom positive or negative pressure value.

  1) different levels of clean room or clean area and non-clean room (area) between the static pressure difference should not be less than 5Pa.

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

  3) for the air cleanliness level is less than 5 (100) of the unidirectional flow of the clean room in the door, the door 0.6m of the indoor work surface dust concentration should not be greater than the corresponding level of dust concentration limits.

  4) If the requirements of the above standards can not be achieved, should be re-adjusted to the new air volume, exhaust air volume, until qualified.

Suspended particles

A, indoor test personnel must wear clean clothes, not more than 2 people, should be located in the test point downwind side and away from the test point, and should remain stationary. The action should be light when changing the point of operation, and should reduce the interference of the personnel on the cleanliness of the room.

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

C. The equipment should be "zeroed" before and after the test.

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

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

The sampling point is generally about 0.8-1.2m from the ground, and should be evenly distributed scientifically and avoid the return air outlet. For any small clean room or local air purification area, the number of sampling points should not be less than 2, the total number of samples can be based on the area of the opening of the root of the second time to find. The minimum number of sampling points corresponds to the number of suspended particles sampling points, the work area measurement point location off the ground 0.8-1.2m or so, the air supply outlet measurement point location away from the air supply surface of 30cm or so, the key equipment or key work activities at the scope of the increase in the measurement point, each sampling point is generally sampling a. After all the sampling is completed, the incubator should be placed in a clean room or local air purification area.

After the end of all the sampling, the petri dish will be placed in a constant temperature incubator culture, time is not less than 48 hours, each batch of culture medium should have a control experiment to test whether the culture medium is contaminated.

Sedimentation bacteria

Work area measurement point location off the ground 0.8-1.2m or so, will have been prepared petri dishes placed in the sampling point, open the petri dish cover, so that it is exposed to the specified time, and then cover the petri dish, the petri dish will be placed in a constant temperature incubator culture, the time is not less than 48 hours, each batch of medium should have a control experiment, to test the medium is not contaminated.

Noise

Measurement height of about 1.2 meters from the ground, the clean room area of 15 square meters or less, you can only measure the center of the room 1 point; area of 15 square meters or more, should also be measured diagonally 4 points, 1 meter from the side walls, measuring points toward the corners.

Illumination

Measuring point plane about 0.8 meters from the ground, according to the 2-meter spacing points, 30 square meters of the room within the measuring point from the side wall 0.5 meters, more than 30 square meters of the room measuring point from the wall 1 meter.