(ISO International Standard 4793 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEXAYHAPOAHAR OPTAHW3AUMA NO CTAHAAPTW3AUMWORGANISATION INTERNATIONALE DE NORMALISATION ANSI International Unit Laboratory sintered (fritted) filters - Porosity grading, classification and designation Filtres frittés de laboratoire-Echelle de porosite-Classification et designation First edition - 1980-10-01 OCT 0 2 1980 S04793-19807E) UDC 542.67.07 :539.217.1 Ref. No. ISO 4793-1980 (E) Descriptors : glassware, laboratory glassware, sintered glass, filters, graduations, porosity, pores, permeability, tests, dimensions, designation classifications Price based on 7 pages Foreword ISo (the International Organization for Standardization) is a worldwide federation of national standards institutes (Iso member bodies). The work of developing Inter- national Standards is carried out through Iso technical committees. Every member body interested in a subject for which a technical committee has been set up has the right to be represented on that committee. International organizations, governmental and non-governmentail, in liaison with iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the Iso Council. International Standard ISO 4793 was developed by Technical Committee ISO/TC 48, Laboratoryglasswareandrelated apparatus,andwas circulatedto the memberbodies inMarch1979. Australia Israel South Africa, Rep. of Canada Italy Spain Czechoslovakia Libyan Arab Jamahiriya Turkey France Mexico United Kingdom Germany, F. R. Netherlands USSR Hungary Poland India Romania No member body expressed disapproval of the document. International Organization for Standardization, 1980 Printed in Switzerland ISO 4793-1980 (E) INTERNATIONALSTANDARD Laboratory sintered (fritted) filters - Porosity grading, classification and designation 1 Scopeandfieldof application 4 Grading of filters This International Standard specifies a system of porosity Filters shall be graded according to their pore size index in one grading, classifying and designating laboratory sintered (fritted) of the eight grades specified in table 1. filters by the determination of pore size index. The designation allotted to each grade consists of the upper It is applicabletolaboratory filters madeof glass, vitreous silica, limit of its pore size index range, expressed in micrometres ceramics, metals and plastic materials. preceded by the letter "p". Test methods are included in annexes B and C for the deter- Filters may be provided in certain materiais or for special pur- mination of air permeability and uniformity of pore size, but poses with pore size indexes falling within narrower ranges these characteristics do not form part of the requirements of than those given in table 1; if so, this should be indicated by this International Standard. stating both the minimum and maximum limits of the range. Table 1 -- Grading of filters 2 Definitions Designation Pore size index, μm 2.1 sintered (fritted) filter : A filter produced from porous of grade > V material formed by the thermal bonding of particles. P1,6 一 1,6 P4 1.6 4 2.2 pore size index : A characteristic of a filter related to P10 4 10 pore diameter. P16 10 16 P 40 16 40 2.3 permeability:A characteristic of a filter related to the P100 40 100 rate of flow through it under specified conditions. P160 100 160 P 250 160 250 Quality 5 Limits forpore size index Filters shall not shed particles under conditions of normal use and shall withstand a working pressure differential of 1,013 bar When the filter is tested in accordance with the method applied in the normal direction of use. specified in annex A, the pore size index shall be within the limits specified in table 1 for its grade. When tested for pore size index by the method specified in annex A, there shall be no evidence of faults in the filter NOTE - It is recom