- May 10, 2018 -
The type of air filter can be divided into Non-woven fabric filter media, synthetic fiber filter media, glass fiber filter media, activated carbon filter media, imported cotton fiber, and long fiber series.
1. Non-woven fabric filter media :
The scientific name of polyester fiber, commonly known as non-woven fabric, and non-woven fabric has extensive use , technology maturity, good stability and other technical characteristics,so it is widely used in coarse, medium efficiency panel filter, bag filter in China now.
The manufacturing process includes meltblown, acupuncture, spunlace, spunbond and multiple processes. Compared with other filter media of the same grade, it has stable quality, large dust content, strong moisture resistance, long service life, economy, durable and other advantages. However, non-woven fabrics also have some disadvantages, that is, large resistance, no environment-friendly (can not be burned or broken down). Non-woven fabrics are also the earliest filter materials used, and the technology is mature and the production cost is low. Although new filter materials emerge continuously in recent years, due to high production costs and high technical standards, it is difficult to popularize. Thus, non-woven filter material in the lower coarse and medium-efficiency filtration environment still has an irreplaceable position due to its low price and high quality. In recent years, due to the continuous progress of technology, the emergence of composite nonwovens has greatly improved the image of cheap and low-grade nonwoven fabrics, and it has been able to achieve sub-HEPA in terms of efficiency.
2. Synthetic fiber filter
Synthetic fiber filter can completely replace non-woven fabric and glass fiber convering coarse, medium and high efficiency (G3-H13) full range of filtration products in general filtration environment. It is a new filter material and the main development direction of future filter media . Compared with other filter media of the same grade, it has the advantages of low resistance, light weight, large capacity, environment-friendly (burnable), and moderate price.
Due to the relative backwardness of domestic processing technology and technical craft in the 1990s, synthetic fiber filters at that time were mainly imported. Although imported filters have excellent performance and high quality, they are expensive. In recent years, with the rapid development of China's domestic air purification industry and rapid growth in market demand, some domestic synthetic fiber filters have the characteristics of good performance, environmental protection, and strong stability, meanwhile enable our customers to enjoy cost-effective performance.
3. Glass fiber filter media:
Glass fiber filter is mainly made of various thickness and length of glass fiber by special processing technology. As glass fiber has high temperature resistance, high efficiency, long service life, environmental protection and other characteristics, it is widely used for in general ventilation system bag filter and high efficiency filter in general ventilation system.
Raw material of glass fiber are mainly imported. Although they have good performance, it has actually high prices. However, glass fiber filters are still widely used in places and environments where air filtration is demanded because of their stable performance, high efficiency, large capacity, high temperature resistance, and long service life.
4. Mported cotton fiber media:
Imported cotton fiber media is actually a new type of filter material made of mixed chemical fiber and cotton fiber. It is mainly used for coarse filtration and pre-filtration of general air-conditioning systems. It is a totally imported filter material imported from abroad. It has the characteristics of low resistance, large dust content, light weight, stable performance, economical and environment protection. It is the ideal product to replace the non-woven fabric in the filter equipment in the future.
5. Activated carbon filter media :
The characteristic of activated carbon is to remove the odor from the air.
Activated carbon filter material refers to activated carbon used combied with coarse, medium and hepa air filters. There are two main forms of activated carbon filter material - granular and activated carbon cotton. As the effect of activated carbon is to remove odors, there is no emphasis on filtration efficiency. In practice, it should generally be used togehter with independent coarse and medium efficiency filters.
Some activated carbon materials can be regenerated. Although the price is more expensive than ordinary coarse filters the use of a reasonable cycle can still reduce the cost of filter operation.
6. Long fiber series:
Polyester fiber, synthetic and fiberglass filter media have corresponding long fiber varieties, and are mainly used for filtering large particles (such as dust of 10 μm) in special occasions e.g. painting workshops. With large dust holding capacity and high catching rate, it can be made into a filter pad or panel filter type structure which is easy to be replaced with pavement. Glass fiber and a small amount of chemical fiber varieties can withstand high temperatures.
Medium efficiency filter
It is essential for general ventilation and air conditioning systems and is the main force for filtering air.
The bag filter type is mainly to meet the requirements of high air volume and low resistance. The correct use of the bag filter is to install a pre-filter device on the front of the bag filter. Generally, a disposable paper frame or a metal frame panel filter is used. The metal panel filter is durable and can be repeatedly cleaned. It is widely used today. This can effectively avoid the bag filter from directly contacting the harsh environment.
During our regular visits to customers, we discovered that in order to save costs and reduce times of installations, some users commonly use bag filters as the first-stage filter after the life-end of the pre-filter on the front end of the bag filter. The bag filter used in a harsh environment will shorten its service life, and could not be used in accordance with the original design requirements of this product. This situation should be avoided as much as possible. On the surface, although the purchase cost of one additional filter is increased, the installation of the pre- filter can extend the replacement cycle of the bag filter through the actual operation of the air conditioner. In the long run, the total maintenance cost will instead Reduced.
High efficiency filter-HEPA filter
The scope of application of HEPA filters is mainly in the electronics, semiconductors, precision machinery, pharmaceuticals, hospitals, food and other industries with high requirements for cleanliness.
Since HEPA filters are generally used as the filtering ends, the requirements for HEPA filters are also the most stringent; Of course, additional “care” is required.
First of all, we must remind customers to extend the lifespan of high-efficiency filters. The most fundamental and simplest method is to keep dust our with the pre-filter. That is, the air passing through the HEPA filter is the air that is already filtered by the pre-filter, the rough filter, and the intermediate-effect filter. At this time, the air should reach the standard of 99. 95% of air with the dust particles smaller, lower pollution.
It should be noted here that replacing a prefilter generally does not require stopping other normal work plans and arrangements. After installation, the normal operation of air-conditioning and fresh air equipment can be operated without debugging. Therefore, experienced customers will pay attention to the pre-filter. For highly clean areas such as Class 10,000 and Class 100,000 clean rooms or operating rooms, F8 filtration (colorimetry test 95%) is suitable for prefiltration. In this way, the service life of the end HEPA filter can generally reach 5 years. In foreign projects and domestic new projects, F8 filter is the most common prefilter for non-uniform flow cleanrooms. For the clean room of the Class 100, Class 10 or higher level of the chip factory, the prefilter has a common efficiency level of H10 (MPPS 85%), and many new projects simply use HEPA (filter efficiency of 0. 30um particles ≥ 99. 97% ). In the past domestic clean room air conditioning system design, the common configuration of the filter is: rough → medium efficiency → high efficiency, in this case high-efficiency filter had a service life of only 1-3 years, and the worst was a few months. It can be seen that the pre-filtering efficiency determines the service life of the end filter.
In some cases, the regulations for the use of high-efficiency filters are not based on consideration of resistance, but other factors. If there is hydrofluoric acid in the plant and the workshop air conditioning is not a fresh air system, the glass fiber filter paper of the high-efficiency filter will be affected by retun air. For safety, HEPA filters must be replaced regularly. At present, some domestic Grade-A hospitals and pharmaceutical plants will actively replace high-efficiency filters after the rainy season every year. The main purpose is to prevent any possible contamination of molds in the filters. Some national First-class three-level hospitals, biological laboratories of pharmaceutical factories, and laboratories dealing with dangerous goods will use new high-efficiency filters to ensure safety and reliability before launching a new vital project.