How to check the expiration date of high efficiency filters by leak detection?
- Author Huang Tianying
First, the use of high efficiency filters
1. Regularly monitor the air cleanliness of the cleanroom according to the monitoring regulations formulated by the company. If abnormal conditions are found, it should be replaced if it is considered to be a high-efficiency filter problem, such as a 70% drop in air supply and leakage.
2. Regularly verify according to the air conditioning purification system verification requirements, and replace them as required when abnormal conditions are found;
3. When abnormal conditions are found in the normal production process, if the pressure difference is unqualified, the air supply volume is not felt, etc., the analysis reason should be replaced when it is determined to be a high-efficiency filter problem;
4. The replacement period specified in the company's documents:
Generally, factors such as the amount of production, the amount of dust generated, etc. should be considered, and it should not be blindly regulated, nor can it be clouded.
Second, the test method for high-efficiency filter leakage uses the dust particle counter method:
Usually, a small sampling instrument such as 2.83 L/min is used, and the limit specified by the dust particle counting method is used as a criterion, or a significant change in the number of particles is found.
Operation method: the sampling port is 23cm away from the filter and the moving speed is 520mm/s. DOP or PAO method
Use the instrument: smoke generator, leak detector.
Method: The sampling head of the receiver is about 2 cm away from the filter, and the inspection speed is within 2~3 cm/s.
Standard: The leak rate should be less than 99.99%.
High efficiency filter leak detection
1, Objective: the amount of leakage through the detector efficiency filter, high efficiency filter and detect defects installed, in order to promptly take remedial measures.
2. Scope: Suitable for leak detection of high efficiency filters in clean areas.
3. Responsible: Quality Department, Production Department.
4, procedures:
4-1 Test method: dust particle counting scanning inspection method.
4-2 Test range: the filter material of the filter, the seal of the filter frame and the connection of the filter group support frame, the support frame and the fixed wall connection.
4-3 Testing equipment: dust particle counter.
4-4 Detection principle: According to the luminous flux principle that the floating particles are scattered under a certain intensity of illumination with a certain proportional relationship with the particle size, the particle scattered light is converted into an electrical signal by photoelectric conversion, and is displayed after being amplified and computerized. Diameter and the number of corresponding particles.
4-5 Test procedure:
4-5-l dust particle counter with a sampling head scanning the wind side of the filter, the sampling head about 2cm distance from the filter, the filter frame along the inspection and the like, the scanning speed is lower than 5cm / s.
4-5-2 When the detection period is 10min, the number of 0.5u m particles is >20, indicating that the leakage amount exceeds the standard. Need to be repaired or replaced.
4-5-3 After sealing or tightening the bolt with epoxy resin, scan inspection will be carried out.
4-6 detection cycle
It should be tested less once a year in normal use, and new high-efficiency filters should be tested.
Check the pressure difference between the two ends of the high-efficiency filter once a year. When the pressure difference reaches three times the initial resistance value, it should be replaced; the air flow speed is reduced to the low limit of Zui, even if the filter is not increased when the filter is replaced, it should be replaced. Efficient; high-efficiency air filter should be replaced when the air volume is 70% of the original air volume; when the high-efficiency air filter has unrepairable leakage, it should be replaced efficiently.
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