试验室差压变送器计量检定中的问题研究

Research on the Problems in Metrological Verification of Differential Pressure Transmitter in the Lab

随着科研生产中差压变送器准确度等级越来越高,量程范围越来越小,现行JJG 882-2004《压力变送器检定规程》已不能很好地解决差压变送器计量与使用中量值传递的相关问题,对差压变送器小量程范围感压口余液影响、压力真空量程范围测量影响两个问题进行了试验研究。试验结果显示,如果不能剔除因差压变送器小量程范围感压口余液影响引入的误差,将会对测量结果产生较大的测量不确定度,尤其对于高精度差压变送器影响更为明显,造成测量误差超出最大允许误差;差压变送器压力真空量程范围影响同样是一个需要明确认识的测量问题,正确使用和计量是保证压力真空量程范围差压变送器输出量值准确的唯一途径。为使差压变送器更好地配合实际科研生产,保证其量值传递准确可靠,有必要对差压变送器的计量和使用制定更明确的规程规范,以对其进行指导。

With the development of scientific research and production, the accuracy of the differential pressure transmitter is higher and higher, while the range is smaller and smaller. The current verification regulation of JJG 882 - 200444 Verification Regulation of Pressure Transmitter” cannot well solve the related issue about quantitative value transfer in metering and use of the differential pressure transmitter. The experimental study onspecific problems of differential pressure transmitter is conducted, including the influence of two aspects,i. e. ,the pressure sensitive mouth affects residual liquid in small range and the vacuum pressure range affects measurement range. The experimental results show that,if the impact of pressure sensitive mouth on residual liquid cannot be clearly understood and reasonably eliminated, then significant measurement uncertainty may be introduced, especially for high precision equipment, the measurement errors may exceed the maximum allowable error. The influence of pressure vacuum range is also a problem shall be clearly understood, and the correct use and measurement is the only way to guarantee the accuracy of the output value. In order to ensurequantitative value transfer of the differential pressure transmitter is accurate and reliable, it is necessary to develop a more clear specification formetrology and use of differential pressure transmitter.