1.1 This specification covers requirements for glass volumetric flasks of precision and general-purpose grades suitable for laboratory purposes.

1.1.1 Class AEach flask of precision grade shall be marked with the letter "A" to signify compliance with applicable construction and accuracy requirements. Flasks may be marked with an identification number (serial number) at the option of the manufacturer.

1.1.2 Class BGeneral purpose flasks are of the same basic design as Class A flasks. However, volumetric tolerances for Class B flasks shall be within twice the specified range allowed for Class A flasks. These flasks need not be marked with their class designation.

Specifications for micro volumetric flasks in sizes from 1 mL to 25 mL, inclusive, are given in Specification E 237.

The Twelfth General (International) Conference on Weights and Measures redefined the litre as a "special name for the cubic decimetre," but agreed to permit continuance of the terms litre, millilitre, and mL, except in association with measurements of the highest precision. For volumetric glassware the difference between the old and new meanings of litre is negligible. Therefore, either mL or cm³ may be marked on ware covered by this Specification.

1.1.3 Product with a stated capacity not listed in this standard may be specified class A tolerance when product conforms to the tolerance reange of the next smaller volumetric standard product listed in .

1.1.4 Wide MouthRequirements for insertion of tablet or capsule for assay dilution and to accommodate access of larger diameter pipets have created demand for introduction of volumetric flasks provided with larger opening. Product with a stated capacity with a wider mouth, not previously listed in this standard, may be specified class A tolerance when product conforms to the tolerance range of the volumetric standard product listed in . In order to avoid confusion, wide neck flask tolerance must be marked on each flask as a requirement.