基于质量流量法的吸阻及通风率标准棒校准系统的设计

Calibration system for draw resistance and ventilation rate standards based on mass flow

为解决传统的体积流量法校准装置在校准吸阻及通风率标准棒时容易受环境温度、大气压力及管路压降等因素影响的问题,搭建了一种基于质量流量法的吸阻及通风率标准棒校准系统。该系统以吸阻及通风率标准棒的下游气体压力、测试环境的大气压力和温度作为修正参数,通过质量流量可调的molbox测量主机、molbloc-S音速喷嘴和自动调节控制单元,产生校准所需的恒定体积流量。采用不同规格吸阻和通风率标准棒对该系统的重复性及稳定性进行测试,并与体积流量法校准装置进行比对,结果表明:①吸阻及通风率标准棒校准结果的稳定性及重复性均优于体积流量法校准装置;②吸阻标准棒校准结果相对偏差的绝对值均≤0.21%,通风率标准棒校准结果绝对偏差的绝对值均≤0.05%,与体积流量法校准结果基本一致。该技术可为提高吸阻及通风率标准棒的校准结果准确性提供支持。

In order to avoid the effects of environmental temperature,atmospheric pressure and pipeline pressure drop when calibrating draw resistance and ventilation rate standards based on volume flow,a calibration system for draw resistance and ventilation rate standards was developed based on mass flow.The system takes the downstream gas pressure of draw resistance and ventilation standards and the atmospheric pressure and temperature of the test environment as correction parameters,and generates the constant volume flow required by calibration through a mass flow-adjustable molbox flow terminal,a molbloc-S sonic nozzle and an automatic control unit.The repeatability and stability of the system were tested with the draw resistance and ventilation standards of different specifications and compared with the calibration device based on volume flow.The results showed that:1)The stability and repeatability of the calibration results of draw resistance and ventilation standards were better when calibration based on mass flow.2)The absolute value of relative deviation of calibration results of draw resistance standards was no more than 0.21%,and that of ventilation rate standards was no more than 0.05%,which were basically consistent with the calibration results based on volume flow.This technique provides a support for promoting the accuracy of calibration results of draw resistance and ventilation rate standards.