Filtration accuracy. The selected filter cloth must meet the filtration requirements of the production process. Reflect the indicators of filtration accuracy of the bubble diameter, the maximum particle size and the initial filtrate turbidity (filtrate allows solids). There are two indicators of the bubble diameter, namely, the maximum bubble diameter and boiling bubble diameter. In general, the maximum bubble diameter is about 2 to 4 times the maximum particle size. Filtration requirements of high concentration is not too high material filtration, the selected filter cloth and the particle size of the maximum particle size to be retained in the particle size should not differ too much, so as to avoid short circuit. However, for filtration with high filtration precision or without filter cake formation, the maximum particle size of the selected filter cloth should not exceed the particle size to be retained in the material to ensure the filtration precision. In addition, the uniformity of the pore of the filter cloth is also very important. It can be described by the ratio of the boiling bubbling pore diameter to the maximum bubbling pore diameter. When the ratio is close to 1, the uniform pore size of the filter cloth is good.