Particulate Matter Sampling Performance of High-Pressure Natural Gas Pipelines Based on Pressure Gauge Ports: A Study of a Safe and Practical Alternative Sampling Approach

Addressing the safety limitations and operational challenges associated with online particulate matter sampling in high-pressure natural gas pipelines, this paper proposes and systematically investigates a non-intrusive, safe sampling alternative utilizing existing pressure gauge tapping ports. Through experimental and Computational Fluid Dynamics (CFD) numerical analyses, the influence of velocity ratio R (ratio of sampling velocity to pipeline gas velocity), pipeline flow velocity V0, and port orientation on sampling efficiency η (ratio of sampled concentration to true concentration) was examined. Results show that sampling via a pressure gauge port exhibits a trend contrary to traditional isokinetic sampling: efficiency increases significantly with R. At R = 2, particles below 10 μm are effectively collected, with notably improved capture for larger particles. Flow field analysis reveals that efficiency enhancement originates from a recirculation zone upstream, expansion of the high-pressure zone downstream, and a “wall impaction–bounce–recapture” mechanism under high R conditions. An empirical efficiency formula was established based on experimental data, with prediction errors below 15%. In field tests at a gas transmission station, applying this correction increased the evaluated filtration efficiency from 9.4% to 50.2%, effectively restoring true operating conditions. This study provides a reliable theoretical basis and practical technical solution for safe, convenient, and accurate particulate monitoring in natural gas pipelines.