【国外标准】 Standard Specification for Laboratory Glass Volumetric Apparatus

This specification covers general requirements for laboratory glass volumetric apparatus of Class A and B. The volumetric apparatus shall be manufactured from glass of suitable chemical and thermal properties, and shall be as free as possible from visible defects. Glasswares with a flat base shall stand firmly without rocking when placed on a level surface. For those requiring stoppers and stopcocks, glass stoppers shall be interchangeable while plastic stoppers used as alternative to glass ones shall be of inert plastic material. Stopcocks, on the other hand, shall permit smooth and precise control of outflow. Glasswares shall have clean, permanent graduation lines of uniform thickness confined to the cylindrical portions of their cross section, with the graduations lines being of Pattern I, II, or III and the unit of volume being cubic centimetre. Units of cubic decimeter or cubic millimetre may be used in special cases; however, only one unit of volume shall be used on the same piece of apparatus. Aside from graduation lines, the glassware shall bear inscriptions of the capacity, the temperature at which it is to be used, the method of use (whether to contain or to deliver), and for those that deliver though an outflow nozzle, the time required to empty the total nominal capacity with unrestricted outflow. Per service requirement, additional provisions may be specified as well.1.1 This specification covers general requirements common to glass volumetric apparatus. Specific dimensions and tolerances for applicable instruments are given in other specifications as cited throughout this specification. Glass must conform to Specifications E438 and be calibrated in accordance with Practice E542.1.1.1 Class A—Each instrument shall be marked with the letter A to signify compliance with applicable construction and accuracy requirements. Instruments may be marked with an identification marker (serial number) at the option of the manufacturer.1.1.2 Class B—General purpose instruments are of the same basic design as Class A. However, volumetric tolerances for Class B instruments shall be within twice the specified range allowed for Class A unless otherwise specified.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.