The specification provides the standard dimensional requirements for obtaining, within practical limits, interchangeability in stopcocks and stoppers for ordinary laboratory and industrial applications. It solely covers ground surfaces dimensional interchangeability, and does not involve design characteristics of the item except where specified. Materials shall be tested and shall conform to the specified values of design, dimension, designation, tolerances, taper, and master gages; as stated in the requirements for Single Straight-Bore Taper-Ground Stopcocks, Single Oblique-Bore Stopcocks, Double Oblique-Bore (Three-Way) Stopcocks, T-Bore and 120-deg Bore Stopcocks, Taper-Ground Flask Stoppers, and Taper-Ground Bottle Stoppers.

1.1 The specification provides standard dimensional requirements for obtaining, within practical limits, interchangeability in stopcocks and stoppers for ordinary laboratory and industrial applications. It covers dimensional interchangeability of the ground surfaces only and does not involve design characteristics of the item except where specified.

Note 1: The dimensions pertaining to stopcocks and stoppers were taken from the Commercial Standard CS 21 of the U.S. Department of Commerce.

Note 2: Although glass is the most commonly used material for stopcocks and stoppers, other materials may be used as specified. Stopcocks and stoppers constructed from glass should conform to Specifications E438 and E671.

1.2 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.