Editing Volumetric flask (section)

==Classes==

Calibration and toleration standards for volumetric flasks are defined in the following standard specifications and practices: [[ASTM International|ASTM]] E288,<ref>{{Citation
|title = ASTM E288 - 10 Standard Specification for Laboratory Glass Volumetric Flasks.
|url = http://www.astm.org/Standards/E288.htm}}</ref> E542,<ref>{{Citation
|title = ASTM E542 - 01(2007) Standard Practice for Calibration of Laboratory Volumetric Apparatus.
|url = http://www.astm.org/Standards/E542.htm}}</ref> E694,<ref>{{Citation
|title = ASTM E694 - 99(2010) Standard Specification for Laboratory Glass Volumetric Apparatus.
|url = http://www.astm.org/Standards/E694.htm}}</ref> [[International Organization for Standardization|ISO]] 1042,<ref>{{Citation
|title = ISO 1042:1998 Laboratory glassware – One-mark volumetric flasks.
|url = http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=25484}}</ref> and [[GOST]] 1770-74.<ref>{{citation
|title = GOST 1770-74 Laboratory volumetric glassware. Cylinders, beakers, measuring flasks, test tubes. General specifications.
|url = http://protect.gost.ru/document.aspx?control=7&id=165630}}</ref> According to these specifications, volumetric flasks come in two different classes. The higher standard flasks (Class A, Class 1, [[United States Pharmacopeia|USP]] or equivalent depending on the country) are made with a more accurately placed graduation mark, and have a unique serial number for traceability. Where this is not required, a lower standard (Class B or equivalent) is used for qualitative or educational work.