ASTM International Standard Practice for Calibrating Gaseous Reference Leaks ASTM E908-98(2004)

This practice establishes the standard procedures for calibrating leak artifacts of a specified gas, that may be used for determining the response of leak detectors, or in other situations where a known small flow of gas is required. The purpose of this practice is to establish calibration without reference to other calibrated leaks in as straightforward a manner as possible using the likeliest available equipment. The two types of leaks considered here are Type I, which is pressure to vacuum, and Type II, which is pressure to atmosphere. Three calibration methods are described under each type of reference leak, as follows: Method A-accumulation comparison using a known volume of tracer gas at specified conditions of temperature and pressure as a reference; Method B-accumulation comparison using a reference leak artifact calibrated using Method A; and Method C-direct measurement of leak rate by timing the movement (displacement) of a liquid slug, by the leak, in a capillary tube of known dimensions.