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To investigate the characteristics and selection principle of filter
Date：2014/4/1 Information Source：本站 Hits：10246
The filter is indispensable processing method to purify the process fluid, mainly used for the removal of fluid or other particles in suspension. The principle is the use of filter media with holes, from a fluid (liquid or gas) to remove contaminants, the fluid to achieve the required level of purity. Filters are often thought to be a simple network or through a sieve, filter or separation is carried out on a surface. This is the way of the past, and now most of the filter wall filter is a certain thickness, namely has the depth filtration equipment, in order to "bend channel" form to the assistant role on the removal of pollutants. Filter is to remove a small amount of solid particles in liquid equipment, when the fluid enters the filter cartridge has a certain size, the impurities are blocked, and clean filtrate from the filter outlet, when cleaning, unscrew the pipe bottom plug, drain fluid, remove the lower flange, remove the cartridge, processing after the re the mount to. As everyone knows, the core of the original filter is a filter, which is a preparation of the microporous supporting layer (support) covered with film more micro pores. There are a lot of making membrane material, divided into the organic membrane (such as polysulfone hollow fiber membrane) and inorganic membrane (such as Tao Cimo). Membrane filter filtration precision is high, size control is relatively stable, and easy backwash recovery performance. Therefore, maintenance is extremely easy to use.
1 filtering mechanism and influencing factors
1.1 filtering mechanism
There are 2 main types of filtration mechanism of fluid. One is based on the size of the particle separation, such as interception, screening and surface capture; another is the adsorption, the particles in the chemical / charge under the action of adhesion in the filter. This requires that all pharmaceutical companies to choose a different filter membranes according to the actual needs of their own.
1.2 factors affecting the filtration
Characteristics of 1.2.1 fluid
Associated with the characteristics of the fluid. For example, the viscosity of the fluid and chemical / ion composition, the greater the viscosity of the fluid velocity and pressure in the same conditions more slowly, more contact between the fluid and the membrane, good filtering effect; moreover, mixing / contact time, fluid and the film also has a great influence on the filtering effect, mixing / contact time the filter the better. In addition, the need to pay attention to is, the characteristics of the fluid only affect the adsorption film on fluid retention effect and not exclude the influence of particle size.
The 1.2.2 operating conditions
Related to the actual operating conditions, such as particle velocity and filtration pressure. To achieve good filtering effect, generally choose low flow velocity, the lower the better retention. Practice has proved that the structure of mobile film is unfavorable to the filter, once the membrane structure changed in the filtering process, then the particles and fibers can be precipitated from the depth filters, affecting the filtering effect. However, the speed / pressure only to retain an important influence on the adsorption, size exclusion effect is quite small.
1.2.3 particle types
Types of particles and the filtering effect is also has the very big relations, particles as variable shaped particles and non deformable particles 2. Under pressure, the deformable particles will enter the filter structurecausing filter mesh more jam, which affect the filtration effect, such as gel filtration. However, no variable particle filter will form a layer cake shaped object in the membrane.
1.2.4 filter type
And filter membrane, different aperture and structure of membrane structure with different, some membrane structure is rigid, some film is moving. The pre nominal pore size membrane does not have a unified national standard, different manufacturers, definitions and methods of their own, so the selection and replacement of merchants need immediate attention, also is 0.22 μ m pre filter, the filtering effect of different manufacturers are different. But the public aperture filtering is regulations defined, each business is the implementation of the same standard, in the selection and replacement is relatively simple.
1.2.5 filtering material
Associated with the filter material, the filter material according to the relationship with the water into the water (water infiltration dear) and hydrophobic (water can not infiltrate) 2. Hydrophilic filter is mainly used in water or mixed aqueous / organic solution, filtering and removing bacteria filter, such as cellulose materials (regenerated cellulose, mixed cellulose ester), PVPP polycarbonate, PVDF two modified polyvinylidene fluoride; hydrophobic filter is through the water by intercepting or "lead" into the membrane, mainly used in solvent, acid, alkali and chemical filtration, tank / equipment apparatus, process for air intake / exhaust filter, fermentation, such as PTFE polytetrafluoroethylene, PVDF polyvinylidene fluoride, two PP, PS, PC.
The 2 filter characteristics and structure
Generally divided into deep filter (primary filter), surface filter (filter membrane filter (middle) and 3 kinds of depth filter). Deep filter fiber off, cannot give an exact aperture, thickness 3 ~ 20mm, usually with adsorption, and the bearing capacity of the larger; surface filter fibers by thermal bonding or film coating into, can give a nominal pore size, relatively thin (< 1 mm), the adsorption capacity is small; the main characteristics of membrane filter is hard texture, not easily broken, there are twists and turns of the channel and a very high internal surface area, there are holes in certain ratio, can do integrity test, commonly used in the deep level filter, such as sterile filter.
1 filtering mechanism and influencing factors
1.1 filtering mechanism
There are 2 main types of filtration mechanism of fluid. One is based on the size of the particle separation, such as interception, screening and surface capture; another is the adsorption, the particles in the chemical / charge under the action of adhesion in the filter. This requires that all pharmaceutical companies to choose a different filter membranes according to the actual needs of their own.
1.2 factors affecting the filtration
Characteristics of 1.2.1 fluid
Associated with the characteristics of the fluid. For example, the viscosity of the fluid and chemical / ion composition, the greater the viscosity of the fluid velocity and pressure in the same conditions more slowly, more contact between the fluid and the membrane, good filtering effect; moreover, mixing / contact time, fluid and the film also has a great influence on the filtering effect, mixing / contact time the filter the better. In addition, the need to pay attention to is, the characteristics of the fluid only affect the adsorption film on fluid retention effect and not exclude the influence of particle size.
The 1.2.2 operating conditions
Related to the actual operating conditions, such as particle velocity and filtration pressure. To achieve good filtering effect, generally choose low flow velocity, the lower the better retention. Practice has proved that the structure of mobile film is unfavorable to the filter, once the membrane structure changed in the filtering process, then the particles and fibers can be precipitated from the depth filters, affecting the filtering effect. However, the speed / pressure only to retain an important influence on the adsorption, size exclusion effect is quite small.
1.2.3 particle types
Types of particles and the filtering effect is also has the very big relations, particles as variable shaped particles and non deformable particles 2. Under pressure, the deformable particles will enter the filter structurecausing filter mesh more jam, which affect the filtration effect, such as gel filtration. However, no variable particle filter will form a layer cake shaped object in the membrane.
1.2.4 filter type
And filter membrane, different aperture and structure of membrane structure with different, some membrane structure is rigid, some film is moving. The pre nominal pore size membrane does not have a unified national standard, different manufacturers, definitions and methods of their own, so the selection and replacement of merchants need immediate attention, also is 0.22 μ m pre filter, the filtering effect of different manufacturers are different. But the public aperture filtering is regulations defined, each business is the implementation of the same standard, in the selection and replacement is relatively simple.
1.2.5 filtering material
Associated with the filter material, the filter material according to the relationship with the water into the water (water infiltration dear) and hydrophobic (water can not infiltrate) 2. Hydrophilic filter is mainly used in water or mixed aqueous / organic solution, filtering and removing bacteria filter, such as cellulose materials (regenerated cellulose, mixed cellulose ester), PVPP polycarbonate, PVDF two modified polyvinylidene fluoride; hydrophobic filter is through the water by intercepting or "lead" into the membrane, mainly used in solvent, acid, alkali and chemical filtration, tank / equipment apparatus, process for air intake / exhaust filter, fermentation, such as PTFE polytetrafluoroethylene, PVDF polyvinylidene fluoride, two PP, PS, PC.
The 2 filter characteristics and structure
Generally divided into deep filter (primary filter), surface filter (filter membrane filter (middle) and 3 kinds of depth filter). Deep filter fiber off, cannot give an exact aperture, thickness 3 ~ 20mm, usually with adsorption, and the bearing capacity of the larger; surface filter fibers by thermal bonding or film coating into, can give a nominal pore size, relatively thin (< 1 mm), the adsorption capacity is small; the main characteristics of membrane filter is hard texture, not easily broken, there are twists and turns of the channel and a very high internal surface area, there are holes in certain ratio, can do integrity test, commonly used in the deep level filter, such as sterile filter.
