The Main Classification of Filter

Nowadays, the filter is widely used in many fields of metallurgy, chemical industry, petroleum, paper making, medicine, food, mining, electricity and urban water supply such as the industrial wastewater, circulating water filtration, the emulsion regeneration, waste oil filtration treatment, casting water system in the metallurgical industry, blast furnace water system and so on. From the use of the filter, we can see that most are liquid equipments which use it to purify the oil or water etc. Generally the filter is used as the indispensible accessories of the valve for the liquid equipment, sanitary valve, stainless steel pipeline, vessel, pressure container. There are so many types, and the main classification includes gravity filter, vacuum filter, pressurized filter, precision filter according to the method of obtaining the driving force for filtration. Now we will separately give a brief introduction about four types.

 

1. Gravity filter

 

What is the gravity filter? It means that it is the push filter formed on the filter medium with the help of the gravity of the suspension and the pressure difference. Generally it is an intermittent operation, such as sand filtration.

 

2. Vacuum filter

 

The vacuum filter is formed at the outlet of the filtrate as a driving force for filtration, which can be divided into intermittent operation and continuous operation. The intermittent operation of the vacuum filter can separated various thicknesses of suspensions. The continuous operation of the vacuum filter is suitable for separating the thick suspensions which contain more solid particles, which is mainly used in the production of chemical medicine, petroleum and other industries. It has the advantages of light weight, easy installation and maintenance, and it has the characteristic of easy operation.

 

3. Pressurized filter

 

What is pressurized filter? It means that it is the filter driving force produced by the pressure at the inlet of the suspension or the mechanical pressing force to the wet materials, which is suitable for the suspensions required large filtration pressure difference. It also can be divided into intermittent operation and continuous operation. The tube type pressure filter and pressurized filter of intermittent operation are often used for the separation of low concentration suspensions, which has the wide applications. And the drum pressurized filter and round pressurized filter of continuous operation can filtrate in the closed housing. The structure is similar to the drum vacuum filter and round vacuum filter. Since the structure is complicated, the application is very few.

 

4. Precision filter

 

For the filtration accuracy, usually the precision filter is between the sand filtration, coarse filtration and ultra-filtration. It means that the raw water passes through the filter cartridge, the impurities are separated and trapped on the wall of the filter cartridge, and the water flows through it, which attains the purpose of filtration. At present, its precision range in the market is 0.2 – 100 microns, which can be used in food, wine, electronics and other industries.