August 27, 2024
The clean room has strict regulations on the humidity, temperature, fresh air volume, status, etc. of the environment to ensure the production quality of the products and the comfort of the personnel's working environment. The entire cleanroom system is equipped with a set of air purification system using primary, medium and high efficiency air filters of the three-stage filter, control the number of dust particles in the clean area as well as the number of settled bacteria and bacterial plankton number, etc., as the end of the filtration device HEPA filters determines the operation of the entire purification system, this article describes the application of hepa filters in the air filtration in the clean room.
1. What kinds of HEPA filters can be divided into in the cleanroom?
Types of HEPA filters for cleanrooms:
One type of HEPA filter with Mini pleat HEPA filter and separator HEPA filter, separator HEPA filter supply port for clean room end air supply filter, the industry said that the last filtration the three-stage filtration, the price is also one of the most expensive.
The frame of the separator hepa filter (optional aluminum profile, galvanized sheet folding frame, wooden frame) has a thickness of 150MM 220MM 292MM, the thicker the dust capacity and air volume will increase with the thicker the filter material is 99.99% of the glass fiber filter paper, filtering dust 0.3UM, temperature resistance of 80 degrees humidity resistance of 80%, the sealing of polyurethane adhesive, commonly used sizes and air volume.
(1) 1000 air volume size 610 * 610 * 150 484 * 484 * 220
(2) 1500 air volume size 630 * 630 * 220 915 * 610 * 150
3) The size of 2000 air volume has 1220*610*150
(4) 500 air volume size of 320 * 320 * 220
These specifications are the most used. Generally used in class 100,000 class 100,000 clean room filtration.
Mini pleat HEPA filters are commonly used in class 100 workshops, class 100 workstations, FFU supporting the use, also known as ULPA filters, the efficiency of up to 99.999% or more, Mini pleat air filters are made of ultra-fine glass fiber media, hot melt adhesive to do the separation, and various types of frames assembled. Design features: high efficiency, low resistance, lightweight, thin thickness, easy installation. Generally used in electronics, medicine, food, and other high-efficiency filter coverage of large purification occasions.
Frame: Aluminum profile Thickness 69MM, 80MM 96MM, Sealant: Polyurethane adhesive Separator: Hot melt adhesive Filter media: Glass fiber filter paper Maximum temperature: 80℃ Maximum humidity: 80% Seal: Neoprene rubber.
Commonly used several specifications
1170*570*69 This specification is used with FFU.
910*610*69 This specification is commonly used in a clean bench
2. Difference between the Mini pleat air filter and separator HEPA filter:
Separator HEPA filter is made of ultra-fine glass fiber as filter material, plywood paper, aluminum platinum as a separator, and wooden or aluminum alloy frame glued and become, with high filtration efficiency, low resistance, large air volume advantages, widely used in a variety of local purification equipment and clean plant.
The Mini pleat HEPA filter is made of ultrafine glass fiber as filter material, hot melt adhesive as the separator, assembled with various kinds of frames, with beautiful frames, and compared with the separator filter, it has the advantages of small volume, lightweight, compact structure, reliable performance and so on under the same air volume.
The main difference between the two is that in the case of the same size and air volume, the resistance of the Mini pleat hepa filter is smaller, the dust capacity will be higher, and the service life will be relatively long.
3. How to choose the HEPA filter and HEPA filter installation?
How to choose HEPA filters and the installation of HEPA filters is a problem that every workshop using air filters has to face.
How to choose HEPA filters
1, HEPA filters are mainly used to capture particles below 0.3um dust and a variety of suspended solids. Adopting ultra-fine glass fiber paper as filter material, each unit is tested by the Nano-flame method, featuring high filtration efficiency, low resistance, and large dust capacity. HEPA filters include Mini pleat HEPA filters and separator HEPA filters, HEPA filters with partition including separator HEPA filters, high-temperature resistant HEPA filters, high humidity resistant HEPA filters, Mini pleat air filters including compact HEPA filters, V type HEPA filter, Gel Seal HEPA Filters, HEPA Knife-edge Frame Mini-pleat Panel Filter, etc.
2, HEPA filters are at the end of the air supply, design selection of high-efficiency filters, should be selected from low to high, which can play a role in protecting the service life of filters at all levels. Such as G-level filtration → F-level filtration → H-level filtration → U-level filtration.
3. The commonly used frames of HEPA filters are wooden frames, plated zinc frames, aluminum frames, and stainless steel frames. The selection of materials for the outer frame of the high-efficiency filter directly affects the price of the high-efficiency filter, and the price quotes of different frames of the high-efficiency filter are not the same under the same conditions.
4, such as in the high-temperature sterilization production of clean equipment or ovens, etc., need to use high-temperature efficient filters. Glass fiber filter media, high temperature resistant special adhesive gasket, high-temperature resistance, instantaneous high temperature up to 300 degrees or more. Of course, the price cost of high-temperature-resistant high-efficiency filters is not the same as the price cost of ordinary high-efficiency filters, because it depends on the different rubber.
5, for the high-efficiency filters to be used in high humidity and high-temperature environments, high-temperature and high humidity resistant filter paper and divider, frame materials must be selected to meet the production requirements. For biological clean room and pharmaceutical clean room, the filter must be made of a metal frame and its surface should not be easy to rust, it is not allowed to use the filter with a wooden frame plate to prevent bacteria from being produced and affecting the qualified rate of the product.
Installation of HEPA filter
1, Before the installation of the HEPA filter manufacturer, the clean room must be comprehensively cleaned and wiped, and if there is any accumulation of dust inside the purified air-conditioning system, it should be cleaned and wiped again to meet the cleaning requirements.
2, The installation direction of the HEPA filter must be correct, and the filter should be installed according to the labeling of the import and export direction of the HEPA filter, and should not be reversed.
3, the HEPA filter should be held lightly during transportation to prevent violent vibration and collision, and should not be forced to load or unload.
4, The frame for installing the HEPA filter should be leveled.
5, the HEPA filter must be replaced only after stopping the air supply of the air conditioning system; the sealing gasket between the filter and the connecting frame must be tight and leak-free to ensure the filtering effect.
4. How long is the replacement cycle of the HEPA filter?
On the HEPA filter replacement standards are organized as follows:
1, we start with the HEPA filter, in the clean room, whether it is installed in the purification of air-conditioning units not end of the large air volume of high-efficiency air filters or installed in the high-efficiency air supply port of high-efficiency air filters, these must have accurate records of the operating time and cleanliness and air volume as a basis for replacement, such as in the case of the use of the norm, the service life of the HEPA filters can be up to one year or more, such as the front-end protection do If the front-end protection is done well, the service life of the HEPA filter can be up to two years or more without any problem, of course, this also depends on the quality of the high-efficiency air filter, perhaps longer.
2, such as the installation of HEPA filters in the purification equipment, such as the air shower room in the HEPA filter, such as the front-end primary filter protection to do a good job of HEPA filter service life can be up to two years or more; such as purification of HEPA filters on the workbench, we can be through the purification of HEPA filters on the table to replace the differential pressure meter prompts, the HEPA filter can be through the clean room on the high-efficiency air filter to detect the wind speed to determine the optimal time for air filter replacement. Decide the best time to replace the air filter, such as FFU fan filter unit on the high-efficiency air filter replacement is through the PLC control system in the prompts or differential pressure meter prompts to replace the high-efficiency air filter.
3, clean plant design specifications for the replacement of HEPA filter conditions are:
The airflow velocity is reduced to the lowest limit, generally lower than 0.35m/s. The resistance is 2 times the initial resistance value;
The resistance reaches 2 times the initial resistance value, and the general enterprise is set at 1.5 times;
For the occurrence of unrepairable leakage, the repair point is not more than 3 points, the total repair area is not more than 3%, and for a single point repair area should not be greater than 2cm X 2cm.
Some of our experienced air filter installers summarized the valuable experience, here to introduce to you, I hope to help you in grasping the air filter replacement time more accurately, in the air conditioning unit when the differential pressure table shows that the air filter resistance arrives at the initial resistance of 2 to 3 times, should be discontinued maintenance or change the air filter.
In the absence of differential pressure table, can be based on the following simple double pattern to choose whether to change:
Observe the color of the filter material on the upstream and downstream sides of the air filter, such as the color of the filter material on the air outlet side is blackened in preparation for replacement;
Touch the air filter outlet side of the filter media with your hand, such as more dust on your hand should be ready to change;
Record the replacement condition of the air filter several times and summarize the best replacement cycle;
If the high-efficiency air filter has not reached the final resistance under the premise of presenting a clean room and the adjacent room pressure difference decreased significantly, the lower middle-effect air filtration resistance may be too large, be prepared to change;
The clean room presents the cleanliness can't reach the design request, or presents the negative pressure, in the middle and lower efficiency air filter doesn't arrive at the time of change, then it is possible that the high efficiency air filter resistance is too big, to prepare for change.
4, HEPA filters in normal use, 1 to 2 years to replace one, but this data is very different. Empirical data can only be in a specific project, after the operation of the clean room verification, to find the clean room suitable for the empirical data, can only provide the clean room air shower room use.
If you expand the scope of application, life deviation is inevitable. Such as testing and replacement of high-efficiency filters in the food packaging plant, laboratory, and other clean rooms, the service life is more than three years.
Therefore, the empirical value of the filter life is not to arbitrarily expand the scope of application. If the system design is unreasonable, the new air treatment is not in place, the clean room air shower dust control program is not scientific, the service life of the high-efficiency air filter is certainly shorter, and some even use less than a year to be replaced.
