An Automatic Particle Sampler with Beta Gauging

Performance test results and operating characteristics of the Wedding & Associates' (W&A) PM10 Beta Gauge Automated Particle Sampler (Sampler), a U.S. EPA Designated Equivalent Method (Designation No. EQPM-0391-081), are reported. The custom, computer-controlled Sampler utilizes BETASOFT?, a multitasking operating system running the high level language application program. The Sampler employs the Wedding PM10 Inlet (Inlet) and Critical Flow Device (CFD). Analysis, calculations and mechanical control are achieved by use of analog sensing and digital logic. The development and testing program included wind tunnel and field tests to verify experimentally its conformity with theoretical calculations of the relationship of collected mass to 3- particle penetration. Use of a ¹⁴C source and a fast-response detector leads to high sensitivity and precision. The instrument has been tested against the Wedding Reference Method Sampler (Reference Method). The 24-hour means of mass concentration values determined by the Sampler, regressed against 24-hour samples collected with the Reference Method, yielded slopes within 1.2 percent of unity, with intercepts less than 1.5 μg/m³ and coefficients of determination (R²) of 0.99 or higher. Resolution is less than 3 μg/m³.