回转体积是膜式燃气表的关键计量指标,国家标准对此有明确规定,要求实际值在额定值的±5—之内.目前膜式燃气表回转体积的测试方法相对较少,对检测装置及软件都有较高要求,测试时间长,准确度低,且较难推广.为此,提出一种简单测试方法.具体方法是:安装18等分采样盘代替膜式燃气表计数;在音速喷嘴式燃气表检定装置上,运用摄像采样燃气表累计体积,根据额定回转体积、输出比、测试脉冲数以及临界流文丘里喷嘴气体的体积,建立运算公式,测出回转体积的误差.分别对G2.5燃气表4 m3/h、0.8 m3/h流量点进行回转体积误差测试,结果表明,该方法便捷、快速、准确度高,测试的重复性达到0.05—.回转体积误差及整表误差都与流量有关,将误差值与流量点绘制成曲线图,通过比较分析,可知两者误差值存在一一对应关系.利用该对应关系,可将该方法用于燃气表示值误差的初校,能有效提升3倍校准效率.%Cyclic volume is the pivotal measurement index of the diaphragm gas meter; in national standard, there is explicit stipulation for it,which is the actual value shall be within ± 5— of the rated value. At present,the test method for cyclic volume of diaphragm gas meter is relatively less,and requirements of the detection device and software are higher;the test time is long, the accuracy is low,and it is difficult to promote. Thus,a simple test method is proposed which the counter of diaphragm gas meter is removed and a sampling plate with 18 equal divisions is installed. In sonic nozzle gas meter calibration device, the camera sampling is used for gas meter cumulative volume,according to the rated cyclic volume,output ratio,test pulse number and the critical flow Venturi nozzle gas volume, the formula is established to measure the error of cyclic volume. Through testing the 4 m3/h and 0. 8 m3/h flow points of the G2. 5 gas meter,the test results show that the method is convenient,rapid and accurate, and the repeatability of the tests is 0. 05—. The error of cyclic volume and the error of meter are all related to the flow rate,and the error value and the flow point are drawn into a graph,they have one-to-one correspondence through the comparison and analysis. Based on this relationship,it can be used to test the indication error of meter;the calibration efficiency is improved up to 3 times.
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