10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
New Test Method for the Low Cost Dust Sensors
KANG-HO AHN, Yong-Hee Park, Woo-Young Kim, Hee-Sang Kim, Hanyang University, R. of Korea
Abstract Number: 609 Working Group: Low-Cost and Portable Sensors
Abstract Why do we need a new test method for the low cost dust sensors? The low cost dust sensors have widely been used recently for the detection of atmospheric particles. The operating principle of these sensors is based on the light scattering of the particles either by a LED or a Laser light. However, the measurement accuracy of the sensors has always been questioned by many users. Two types of test methods are known for the evaluation of the sensors, i.e., a chamber method and a continuously flowing low speed wind tunnel method with several different types of test particles. A cigarette smoke, Arizona Road Dust, KCl, and many other types of materials have been used for the sensor performance evaluation. In this test method, KCl has been used not only because of the easiness of the size distribution control, but also the easiness of handling. The density and the purity of the KCl are also well defined.
Experimental method KCl solution is sprayed in order to generate droplets, and then mixed with clean dry air to evaporate droplets. This process will make solid KCl particles. The static charge of the particles will be neutralized by a soft X-ray. These particles are diluted with clean dry air again. And then particles are introduced into the test duct. The cross section of the test duct is a regular quadrilateral. The flow velocity at the test section in the duct should be 0.1 ± 0.05 m/s at all 5 measurement points. The flow velocity measurement points are the centers of the each quadrant of the cross-section of the test duct. In addition, the particle concentration uniformity in the test duct at the 5 sampling points should not exceed 15% of the mean value of the 5 measurement points. The 5 flow uniformity measurement points are identical to the 5 particle sampling points. The 3 test specimens are place in the test duct with a research grade reference particle counter sampling probe that is inserted into the test duct. And then KCl particle concentration is exponentially decreased as a function of time in the test duct. The low cost dust sensor readings and the reference particle counter data are plotted on a semi-log graph as a function of time. From this test results one can easily figure out not only the dynamic performance of the low cost sensors but also the accuracy of the sensors with very short sensor evaluation time. The sensor test time usually takes less than 10 minutes. More detailed test procedure and some of the test results will be presented at the conference.