电子式温度补偿膜式燃气表计量性能测试

Metrological performance test for diaphragm gas meter with electronic temperature compensation

电子式温度补偿膜式燃气表不改变原来膜片正常计量方式,仅仅通过数据修正转换,较好地实现标准温度下的气体体积计量,但由于其显示分辨力过低,导致测试准确性很差,影响该产品的市场推广。该文在不改变燃气表结构的基础上,提出一种用户模式与检测模式的解决方法,两种电路分别对应这两种模式下的显示方案,通过按键控制电路,达到切换具体模式的目的。用户模式下显示分辨力为10 L,满足平时贸易结算的需求;在检测模式下达到0.01 L,符合检测时的准确度要求。以音速喷嘴作为测试标准器,采用图像摄像采样方式读取温补表的标准温度下的体积读数,利用流过音速喷嘴的气体达到临界流状态时,流过喷嘴的气体质量流量保持不变的原理,获得标准温度下的实际体积值。在不改进测试装置的前提下,对温补表进行-20℃温度下的示值误差测试,测试结果重复精度0.11%,缩短检测时间96%。

The electronic temperature compensation diaphrag gas meter does not change the normal measurement mode of the original film. Only through the data correction conversion,it is better to realize the gas volume measurement under the standard temperature. However,because of its low display resolution,the accuracy of the test is very poor,which affects the market promotion of the product. On the basis of not changing the structure of the gas meter,a solution of the use mode and the test mode is put forward.The two circuits correspond to the display schemes under the two modes,and the specific mode is achieved through the key control circuit. The display resolution is 10 L in use mode,which meets the demand of normal trade meter reading,and reaches 0. 01 L in test mode,which accords with the accuracy requirement in testing. The sonic nozzle is used as a standard device,using the image sampling method to read the volume value of the gas meter under the standard temperature,the gas mass flow through the nozzle remains the same principle when the gas flow through the sonic nozzle reaches the critical flow state,obtain actual volume at standard temperature. Under the premise of not improving the test device,the indication error is tested at the temperature of-20 ℃,the repeatability of the test results is 0. 11%,and the detection time is reduced by 96%.