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Electronic Workshop Cleanroom HEPA Filter Maintenance Knowledge

2018-05-14

In the dust-free workshop of the electronics factory, various kinds of high-efficiency filters are widely used. In the daily maintenance of clean and clean rooms and various clean workshops, the maintenance of air filters is a big expense, but the air cleanliness Maintenance is necessary For production environment pollution requirements, what are the standards for high-efficiency filter maintenance and installation and replacement? In the packaging, transportation, installation, and use of air filters, especially high-efficiency air filters, According to the manufacturer's standard requirements, in order to ensure the use of high-efficiency air filters. After various types of air filters are used for a period of time, various dusts are trapped on the surface of the filter media, so that the air filter's filtration efficiency and air filter resistance are reduced, affecting the central air conditioning unit or the high efficiency of clean engineering. The air volume, cleanliness, and efficiency of use of the tuyere require that the air filter be replaced in time to ensure air cleanliness requirements. The following are some issues that should be noted in the maintenance of air filters:

1) Before the installation of various types of air filters, it is not allowed to tear or open the packaging bag or the packaging film by hand; the air filter should be stored strictly according to the direction indicated on the HEPA filter packing box; during the handling of the HEPA filter In the meantime, you should take it gently and gently to avoid violent vibrations and collisions.

2) For high-efficiency filters, the installation direction must be correct: when corrugated plate filter is installed vertically, the corrugated plate must be perpendicular to the ground; the connection of the filter between the vertical and the frame must not be leaky, deformed or damaged. And leakage of glue, etc., after installation must ensure that the inner wall is clean, no floating dust, oil, rust and debris and so on.

3) Test method: Observe or check with a white silk cloth.

4) Before the HEPA filter is installed, the clean room must be fully cleaned and wiped. If there is dust inside the air-conditioning system, it should be cleaned and wiped again to meet the cleaning requirements. If a high-efficiency filter is installed in a technical interlayer or suspended ceiling, full sweeping and wiping should also be performed in the technical floor or suspended ceiling.

5) Transport and storage of HEPA filters should be placed in the direction of the manufacturer's mark. During transportation, it should be handled gently to prevent violent vibration and collision, and it must not be forcibly handled.

6) Before installing the HEPA filter, the packaging must be unpacked at the installation site for visual inspection, including: whether the filter paper, sealant and frame are damaged; whether the length, diagonal and thickness of the filter meet the requirements; the frame has no burrs and Rust (metal frame); whether there is product certification, technical performance meets the design requirements. Then in accordance with the national standard "clean room construction and acceptance specifications" [JGJ71-90] for inspection methods, qualified should be installed immediately.

7) High-efficiency filters with cleanliness levels equal to or higher than Class 100 cleanrooms shall be leak tested before installation in accordance with the methods specified in the “Construction and Acceptance Specifications for Cleanrooms” [JGJ71-90] and shall meet the specified requirements.

8) When installing a high-efficiency filter, the arrow on the outer frame should be consistent with the airflow direction; when it is installed vertically, the folding direction of the filter paper should be perpendicular to the ground.

9) Install rough plate or folding filter, the galvanized mesh should be in the direction of the back of the wind. When bag filters are installed, the length of the filter bags should be perpendicular to the ground, and the filter bags should not be installed parallel to the ground.

10) Under normal conditions of use, the flat or foldable coarse or medium efficiency filter is generally replaced from January to March. If the area is not strict, the filter material can be replaced and can be soaked with clean water containing detergent. Rinse, then dry and replace; after 1-2 flushes, a new filter must be replaced to ensure filtration efficiency.

11) For bag rough or medium efficiency filters, under normal use conditions (average of 8 hours per day, continuous operation), generally 7-9 weeks should be replaced with new ones.

12) For sub-high efficiency filters, under normal use conditions (average 8 hours per day, continuous operation), generally 5-6 months, should also be replaced.

13) For the above filters, if there is a differential pressure gauge or differential pressure sensor before and after the filter, the rough filter must be replaced when the differential pressure is greater than 250 Pa; for the intermediate efficiency filter, the differential pressure is greater than At 330Pa, it must be replaced; for sub-high efficiency filter, when the pressure difference is greater than 400Pa, it must be replaced, and the original filter can not be reused;

14) For high efficiency filters, when the resistance of the filter is greater than 450 Pa; or when the airflow speed at the outlet is minimized, the airflow speed cannot be increased even after replacing the coarse and medium efficiency filters; or when Unrepairable leakage occurs on the surface of the filter, and new high-efficiency filters must be replaced. If there is no such condition, the filter can be replaced one or two years depending on the conditions of the environment.

15) In order to give full play to the role of the filter, in the selection and use process, the upstream wind speed of the filter, coarse and medium efficiency filter should not exceed 2.5m/s, and the sub-high efficiency filter and high efficiency filter should not exceed 1.5. m/s, this not only helps to ensure the efficiency of the filter, but also extends the service life of the filter and saves costs.

16) During the operation of the equipment, generally do not replace the filter; if the filter cannot be shut down due to the replacement period of the filter, the coarse and medium efficiency filters can only be replaced in the case of non-stop fan; the sub-high efficiency filter and high efficiency filter It must be stopped before it can be replaced.

17) The seal between the filter and the connecting frame must be tight and leak-free to ensure the filtering effect.

18) For high efficiency filters that need to be used in environments with high humidity and high temperatures, filters, partitions, and frame materials that are resistant to high temperatures and high humidity must be selected to meet production requirements.

19) Biological clean room and medical clean room must use metal frame filter, and its surface should not rust easily. It is not allowed to use wooden frame filter to prevent bacteria and affect the product's qualification.

In summary, the strict implementation of the filter maintenance and maintenance system and the application of reasonable maintenance measures can ensure the filter's service life and effectiveness, save the company's expenses and bring good economic benefits.

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