ASTM D7278-11

1.1 This guide covers the application of routine calculations to estimate sample system lag time, in seconds, for gas, liquid, and mixed phase systems.

1.2 This guide considers the sources of lag time from the process sample tap, tap conditioning, sample transport, pre-analysis conditioning and analysis.

1.3 Lag times are estimated based on a prediction of flow characteristics, turbulent, nonturbulent, or laminar, and the corresponding purge requirements.

1.4 Mixed phase systems prevent reliable representative sampling so system lag times should not be used to predict sample representation of the stream.

This standard does not purport to address all of the safety concerns, 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.