Gas Sampling Measurement - Sample Probe Minimum Insertion Depth Requirement

March 30, 2017

Research has been completed on assessing the required sample probe insertion depth into the pipeline. Most gas sampling standards state that the probe should be inserted into the center 1/3 of the pipe diameter, but the origin of this requirement is unknown. Long sample probes can lead to mechanical failure of the probe due to fatigue induced by vortex shedding. When a gas stream is free of liquid, the length of the sample probe has little effect on the error in measuring the gas composition as the gas stream is relatively uniform. However, when the gas has small qualities of liquids, the sample probe should avoid being placed in areas of high liquid concentration to avoid over estimation of the heating value of the gas and damage to gas chromatograph equipment.

This research showed that the length of the sample probe can be significantly shorter than the guidance from the standards, which helps to avoid the ingestion of liquids into the sampling system. The results will be presented in an upcoming webinar. PRCI members can find the associated research report on the project page. (PRCI Project MEAS-3-1)