Study on the calibration and uncertainty evaluation of direct-reading atmospheric samplers by laminar flow differential pressure mass flowmeter

Abstract

Air sampler is an important measuring instrument for environmental monitoring. With the rapid development of environmental protection industry, the direct reading air sampler has been widely used and this is also related to the improved develop rate of new products. As it only aims at the situation that the standard meter is soap film flowmeter and the measured meter is rotor air sampler, the JJG 956-2013 metrological verification regulation for air sampler is not applicable to the direct reading air sampler. Meanwhile, the corresponding standard meters are also developing rapidly and more results showed that the laminar differential pressure mass flowmeter has more advantages than the soap film flowmeter in the regulation. It can not only improve calibration efficiency, but also realize automatic calibration or remote calibration. In this paper, the method of calibrating direct reading air sampler by laminar flow differential pressure mass flowmeter is studied. The mathematical model of flow rate and relative indication error used in the calibration condition is proposed, and the uncertainty of indication error is also analyzed in detail. In addition, the evaluation example is given accordingly, which fills the blank in the regulation.