Investigation of Components for Flow Calibration in Particulate Matter Samplers

Particulate matter samplers serve as essential instruments for air monitoring, facilitating the sampling and assessment of air quality. Conventionally, orifice flowmeters utilized for flow calibration in these samplers have demonstrated inadequate linearity and long-term stability, exhibiting significant uncertainty in flow measurement within the prevalent range of 1-120 L/min. This research aims to unveil alternative components capable of enhancing the flow calibration of particulate matter samplers. An in-depth analysis was conducted, scrutinizing the merits and shortcomings of various flowmeters in relevance to their applicability in sampler flow calibration. Priority was given to the design of orifice plates and nozzle components that assure precise manufacturing and cost-efficiency. Employing Computational Fluid Dynamics (CFD), simulations were executed to evaluate the performance of these components across distinct flow ranges. Components manifesting superior linearity within the 1-120 L/min range were selected for further processing. Compliance with national standards for differential pressure flowmeters and adherence to simulation-derived structural parameters were ensured during the manufacturing of these components, followed by rigorous experimental validation. The study culminates in the design of orifice flowmeters optimized for flow ranges of 0.5-5 L/min, 5-10 L/min, and 10-120 L/min, proving instrumental for the flow calibration of particulate matter samplers. Within these ranges, the orifice flowmeters exhibit commendable mechanical processing consistency, an outflow coefficient linearity surpassing 1.0%, and long-term flow stability within a 1.5% margin. These findings are instrumental, providing pivotal theoretical insights for the future design of gas sampler flow calibration components and broadening the array of choices available for sampler flow calibration components.