This Standard is modified in relation to ISO 13521:1999 "Laboratory Sintered (Fritted) Filters — Porosity Grading, Classification and Designation".
1 Scope and field of application
This Standard specifies a system of porosity grading, classifying and designating laboratory sintered (fritted) filters by the determination of pore size.
This Standard is applicable to laboratory sintered filters made of glass, vitreous silica, ceramics, metals and plastic materials.
2 Quoted Standards
GB/T 5249 Permeable Sintered Metal Materials — Determination of Bubble Test Pore Size
GB/T 5250 Permeable Sintered Metal Materials — Determination of Fluid Permeability
3 Definitions
3.1 Sintered (fritted) filter: A filter produced from porous material formed by the thermal bonding of particles.
3.2 Pore size: measured maximum equivalent capillary diameter. Measures the pressure at which the first air bubble breaks away from the filter under specified conditions (test gas is passed through the test specimen which had been immerged into test solution); this pressure is then used to calculate the maximum equivalent capillary diameter.
3.3 Permeability: A characteristic of a filter related to the rate of flow through it under specified conditions.
4 Grading and Designation of Filters
Filters shall be graded according to their pore size in one of the eight grades specified in Table 1. For special requirements, pore size may less than those specified Table 1, however, pore size range shall be indicated.
The designation allotted to each grade consists of the upper limit of its pore size range, preceded by the letter “P”.
Table 1 Grading and Designation of Filters
Designation Pore size (μm)
> ≤
P1.6
P4
P10
P16
P40
P100
P160
P250 —
1.6
4
10
16
40
100
160 1.6
4
10
16
40
100
160
250
5 Technical Requirements
5.1 Filters shall not shed particles under conditions of normal use and shall withstand a working pressure differential of 1.013 × 105 Pa applied in the normal direction of use.
5.2 Limit of pore size
When the filter is tested in accordance with the method specified in Appendix A, the pore size shall be within the limits specified in Table 1 for its grade and near the centre of the range of the appropriate grade.
5.3 Uniformity of pore size
If it is required to assess the uniformity of the filter over its working area, the method of test described in Appendix B should be used.
5.4 Permeability
If it is required to measure the permeability of the filter, it should be tested in accordance with the method described in Appendix C, and should not have a permeability less than the value specified in Table 2 for its grade.
