瞬时流量法检测电子式燃气表计量性能

电子式燃气表通过传感器在采样周期测得瞬时流量,与采样周期相乘积得到累积流量。将各个采样周期内的数值累计,得到测试时间内的累积流量。按目前累积流量法测试误差,需要通过固定的脉冲当量计量累积流量,存在所采集累积值与实际值不一致、测试时间较长、标准装置累积值计算不够准确等问题。基于音速喷嘴气体流量标准装置和电子式燃气表输出瞬时流量的特点,标准装置通过光电头按照近红外通信协议与燃气表实现信息交互,实现瞬时流量法测试误差,有效解决了上述问题。描述瞬时流量法测试的方法原理,通过用0.5级音速喷嘴标准装置按两种方法测试G1.6规格超声波燃气表qmax、0.2qmax、qmin三个流量点误差各6次,两种方法测试误差的差异小于0.2MPE,瞬时流量法测试6次的标准偏差在0.12%以内,验证该测试方法的准确性;检测时间由30 min缩短为5 min,提升效率80%左右。该瞬时流量法值得推广使用,满足快速、准确、高效测试要求。

Testing the Metrological Performance of Electronic Gas Meter by the Instantaneous Flow Method

Electronic gas meters measure the instantaneous flow through the sensor in the sampling period,obtain the accumulated flow by multiplying the instantaneous flow with the sampling period,and obtain the accumulated total quantity during test period by cumulating the values in each sampling period.However,for the measurement of its performance,the cumulative flow method is commonly adopted,and the cumulative flow needs to be measured based on a fixed pulse equivalent.Therefore,there are some problems,such as inconsistency between the collected cumulative value and the actual value,longer testing time,inaccurate calculation of the cumulative value of the standard device.Based on the characteristics of the sonic nozzle gas flow standard device and the instantaneous flow output of the electronic gas meter,an error measurement method based on the instantaneous flow method was proposed,which can effectively solve the above problems by realizing information exchange of the standard device with gas meter through optical interface according to near infrared communication protocol.The principle and method of instantaneous flow measurement were described.Tests by two methods carried out on a G1.6 ultrasonic gas meter six times at qmax,0.2qmax and qmin flow points respectively with a class 0.5 sonic nozzle standard device showed that the difference between the two methods was less than 0.2 MPE,the standard deviation of 6 measurements by instantaneous flow method was within 0.12%,which verified the accuracy of the proposed test method.The test time was shortened from 30 min to 5 min,increasing the efficiency by about 80%.The instantaneous flow method meets the requirements of rapid,accurate and efficient and is worth popularizing.