1.1 This specification describes requirements for a tube that measures the erythrocyte sedimentation rate (ESR). ESR is the suspension stability of red cells in diluted, anticoagulated human blood.

1.1.1 The use of the term "rate" is, strictly speaking, not correct. The test measures the amount of settling of red cells after a specified time.

1.2 The tubes are used together with a special rack to ensure they remain in a vertical position during the test.

1.3 This specification includes many dimensional requirements that are, for the most part, in agreement with the British Standards Institution, German Standards Institute, International Committee for Standardization in Haematology, and the National Committee for Clinical Laboratory Standards publications on Westergren tubes. The clinical procedure using the tube described in this specification is known as the "Westergren Method."

1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.