Clean room filter replacement

A clean room is an air purification device that can provide a locally high cleanliness environment. The clean room is mainly composed of a box, a fan, a primary air filter, a damping layer, lighting fixtures, etc., and the outer shell is sprayed with plastic. This product can be hung or supported on the ground, with a compact structure and easy to use. It can be used individually or connected in multiple ways to form a belt shaped clean area.

Precautions for replacing the clean room filter:
1. Regularly wipe the laminar flow air supply unit FFU, clean the interior of the dust-free room, anti-static curtains, and maintain cleanliness.
2. After regularly replacing the high-efficiency filter, the FFU technical parameters of the laminar air supply unit should be retested to meet the requirements before continuing to work. The cycle for replacing high-efficiency filters is generally one and a half years.
3. Regularly replace the primary filter. The primary filter installed in the clean room should be replaced every three months. If installed in a normal environment, it should be replaced every month.

As a component of different air purification equipment, the replacement time of high-efficiency filters also varies.
① The replacement of high-efficiency filters on the FFU fan filtration unit is carried out through prompts in the PLC control system or pressure differential gauge;
② The high-efficiency filter on the clean room can determine the optimal time for replacing the air filter by detecting the wind speed of the high-efficiency air filter;
③ We can replace the high-efficiency filter on the purification workbench by following the prompts on the differential pressure gauge on the workbench, and install the high-efficiency filter in the purification equipment;
④ The high-efficiency filter in the fully automatic air shower room, such as the well protected front-end primary filter, can have a service life of more than two years.

Common knowledge of air filtration in clean rooms

Filter material
Effectively intercepting dust particles without creating excessive resistance to the airflow. The disorderly interweaving of fibers forms countless barriers to particles, and the wide space between fibers allows airflow to pass smoothly.

efficiency
The ratio of the amount of dust captured by the filter to the amount of dust in the unfiltered air is called the "filtration efficiency". Particles smaller than 0.1 μ m (micrometers) mainly undergo diffusion motion, and the smaller the particles, the higher the efficiency; Particles larger than 0.5 μ mm mainly undergo inertial motion, and the larger the particle, the higher the efficiency.

resistance
Fibers cause airflow to bypass, resulting in minimal resistance. The sum of the resistance of countless fibers is the resistance of the filter. The resistance of the filter increases with the increase of air flow rate. By increasing the area of the filter material, the relative wind speed passing through the filter material can be reduced, thereby reducing the resistance of the filter.

dynamics
The captured dust creates additional resistance to the airflow, so the resistance of the filter gradually increases during use. The captured dust forms new obstacles, resulting in a slight improvement in filtration efficiency. The captured dust mostly accumulates on the windward side of the filter material. The larger the area of the filter material, the more dust it can accommodate, and the longer the lifespan of the filter. The more dust accumulates on the material during its service life, the greater the resistance. When the resistance reaches a level that is not allowed by the design, the lifespan of the filter comes to an end. Sometimes, excessive resistance can cause the dust already captured on the filter to scatter, and when this secondary pollution occurs, the filter should also be scrapped.

static electricity
If the filtering material or dust carries static electricity, the filtering effect can be significantly improved. Due to static electricity, dust changes its trajectory and collides with obstacles, and electrostatic forces participate in the adhesion process.

Filtration efficiency
Among the factors that determine filtration efficiency, the meaning of "quantity" of dust is diverse, and the calculated and measured values of filter efficiency are also different. In practice, the total weight of dust and the number of dust particles; Sometimes it refers to the amount of dust with a typical particle size, and sometimes it refers to the amount of all dust; There are also specific methods that indirectly reflect the concentration of light (colorimetric method) and fluorescence (fluorescence method); There is an instantaneous quantity of a certain state, as well as a weighted average of the efficiency values of the entire dust generation process. Testing the same filter using different methods will result in different efficiency values. Without testing methods, filtering efficiency cannot be discussed.

Filter resistance
Filters create resistance to airflow. The filter accumulates dust and resistance increases. When the resistance increases to a certain specified value, the filter is scrapped. The resistance of the new filter is called "initial resistance"; The resistance value at the time of scrapping the corresponding filter is called the "final resistance". The choice of final resistance is directly related to the service life of the filter, the range of changes in system air volume, and system energy consumption. In most cases, the final resistance is 2-4 times the initial resistance.