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    ISO 17


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    ISO 17:1973 Guide to the use of preferred numbers and of series of preferred numbers

    ISO 17 replaced ISO Recommendation R 17-1956 drawn up by Technical Committee ISO/TC 19, Preferred numbers after the approval from the member bodies from the countries like Norway, United Kingdom, Chile, Pakistan, Ireland, France, India, Austria, Japan, Mexico Netherlands, Poland Etc
    Captain Charles Renard 1877, an officer in the engineer corps, made a rational study of the elements necessary in the construction of lighter-than-air aircraft. He calculated the specifications for cotton rope according to a grading system, such that this element could be produced in advance without prejudice to the installations where such rope was subsequently to be utilized. Recognizing the advantage to be derived from the geometrical progression, he adopted, as a basis, a rope having a mass of grams per meter, and as a grading system, a rule that would yield a tenth multiple of the value an after every fifth step of the series, i.e. :
    a X q5 = 10a or
    whence the following numerical series :
    a 10a
    the values of which, to 5 significant figures, are :
    a 1,5849 a 2,5119 a 3,9811 a 6,3096 a 10 a
    Renard’s theory was to substitute, for the above values, more rounded but more practical values, and he adopted a power of 10, positive, nil, or negative. He thus obtained the following series :
    10 16 25 40 63 100
    which may be continued in both directions.
    From this series, designated by the symbol R 5, the R 10, R 20, and R 40 series were formed, each adopted ratio being the square root of the preceding one :

    The first standardization drafts were drawn up on these bases in Germany by the Normenausschuss der Deutschen Industrie on 13 April 1920, and in France by the Commission Permanente de standardization in document X of 19 December 1921. These two documents offer few differences, the commission of standardization in the Netherlands proposed their unification. An agreement was reached in 1931 and, in June 1932, the International Federation of the National Standardizing Associations organized an international meeting in Milan, where the ISA Technical Committee 32, Preferred numbers, was set up and its Secretariat assigned to France.
    Later, the ISA Technical Committee 32 held a meeting in Stockholm; sixteen nations were represented: Austria, Belgium, Czechoslovakia, Denmark, Finland, France, Germany, Hungary, Italy, Netherlands, Norway, Poland, Spain, Sweden, Switzerland, U.S.S.R.
    With the exception of the Spanish, Hungarian, and Italian delegations which, although favorable, had not thought fit to give their final agreement, all the other delegations accepted the draft which was presented. Furthermore, Japan communicated by letter its approval of the draft as already discussed in Milan. As a consequence of this, the international recommendation was laid down in ISA Bulletin
    The Technical Committee ISO/TC 19, Preferred numbers, was set up and France again held the Secretariat. This Committee at its first meeting, which took place in Paris in July 1949, recommended the adoption by ISO of the series of preferred numbers defined by the table of ISA Bulletin 11, i.e. R 5, R 10, R 20, R 40. This meeting was attended by representatives of the 19 following nations : Austria, Belgium, Czechoslovakia, Denmark, Finland, France, Hungary, India, Israel, Italy, Netherlands, Norway, Poland, Portugal, Sweden, Switzerland, United Kingdom, U.S.A., U.S.S.R.
    During the subsequent meetings in New York in 1952 and in the Hague in 1953, which were attended also by Germany, the series R 80 was added and slight alterations were made. The draft thus amended became ISO Recommendation R 3.

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