Revised Standard from Last Update.

NATIONAL FOREWORD

This draft Indian Standard (Part 7) (Third Revision) which is identical with ISO 506 : 2020 ‘Rubber latex, natural, concentrate - Determination of volatile fatty acid number’ issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on recommendation(s) of the Methods of Test for Rubber and Rubber Products Sectional Committee and approval of the Petroleum, Coal and Related Products Division Council.

The second revision of this standard was published in 2005 under dual numbering by adopting ISO 506 : 1992.

The third revision of this standard has been undertaken to align it with the latest published ISO 506 : 2020. The main changes in this revision are as follows:

— in 5.3,the recommendation for re-standardization of the standard solution has been added;

— in 5.5, silicone antifoaming agent has been added;

— in 6.6, qualitative filter paper has been added;

— two new sub clauses, 5.6 and 6.7 have been added;

— a sentence has been added in 8.2 to precise the change of colour according to the indicator used;

— precision data have been added in Annex A.