AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Design, Testing, and Validation of a Calibration Chamber for Particles
Wendy Merkley, KORI MOORE, Randy Martin, Michael Wojcik, Utah State University
Abstract Number: 315 Working Group: Instrumentation and Methods
Abstract A multi-port fixture has been developed to provide a controlled, uniform measurement environment for the cross calibration of particle point sensors. The system includes an inlet HEPA filter, a port for test particle introduction, four sampling ports in a plane perpendicular to the flow, an exhaust HEPA filter, and a vacuum system. The chamber consists of 10 cm diameter stainless steel tubing sections with custom ports for aerosol introduction, aerosol sampling, and flow measurement. Flow disturbances upstream of the sampling plane were designed to be sufficiently distant to achieve laminar flow before reaching the sampling plane. Flow uniformity across the plenum cross section just upstream of the sampling plane was verified using a hot wire anemometer prior to each sample period. Isokinetic sampling over a range of common flow rates was achieved through design of dedicated sampling nozzles. The uniformity of particle distribution across the sampling plane was assessed through measurements at multiple positions on the sampling plane using optical particle counters (OPCs). A powder with a polydisperse size distribution was utilized in all particle uniformity tests. Inter-OPC calibrations were derived using collocated ambient samples and applied to all measurements to minimize instrument bias. The results of this test demonstrated no apparent bias in particle distribution. Therefore, this plenum system may be used to inter-compare and calibrate aerosol sensing instrumentation and/or to characterize the microphysical properties of a test aerosol using various measurement techniques.