Research On Traceability Method Of Digital Air Sampler

With the rapid development of China’s economy and the continuous improvement of people’s living standards,people pay more and more attention to environmental protection.Environmental protection is inseparable from the measurement of pollutant concentration in ambient air.Air sampler is a necessary sampling instrument for measuring the concentration of pollutants in the air.The flow conversion method in the national metrological verification regulation JJG956-2013 air sampler is only applicable to the air sampler controlled by rotameter.At present,in the actual environmental monitoring work,the digital display air sampler has occupied a dominant position,and its traceability method has been concerned by the majority of environmental protection workers.In this paper,the rotameter type air sampler and the digital display type air sampler are compared and tested,the difference between the two air samplers in flow control mode is clarified,and it is determined that even under the load state,the flow shown by the standard flowmeter and the digital display type air sampler are also in the same state,and the comparison can be carried out directly without considering the load conversion.In order to further ensure the accuracy of flow,the traceability method of temperature and pressure of digital display air sampler is also the focus of this paper.The influence of each parameter on flow is analyzed through single variable experiment to quantify the influence degree,so as to determine the technical indexes of each parameter.This paper studies the confirmation of various parameters and technical indexes of digital display air sampler,the selection of standard instruments and measurement methods,confirms the rationality of the selected standard instruments through uncertainty evaluation,and determines the ambient temperature range for measuring the value of digital display air sampler through environmental test.Technical indexes of various parameters of digital display air sampler: the maximum allowable error of flow is ± 5%;Maximum allowable error of ambient temperature ± 3 ℃;The maximum allowable error of the temperature in front of the flowmeter is ± 3 ℃;Maximum allowable error of atmospheric pressure ± 1.5 kPa;The maximum allowable error of the pressure in front of the flowmeter is ± 1 kPa.Standard instrument selected: electronic soap film flowmeter,grade 1.0;Thermometer,maximum allowable error ± 1 ℃;Digital barometer,maximum allowable error ± 0.5 kPa;Digital pressure gauge,(-30 ～ 30)kPa,class 0.5.Ambient temperature range(10 ～ 35)℃.According to the research results of this paper,a local metrological verification regulation of Hebei Province has been formed,which has been widely recognized by the environmental protection and metrological industry in the process of use.