美国标准局目前正研究用一种新的连续闭环测量方法对环境温度下的气体流量与质量流量标准进行直接对比。当前虽然还没有完善的气体流量标准,但六年来已证实液化气体的准确度可达0.2%以上。近年研究的低温流量标准就是液化系统。可以相信,当装置改进后,液化气体系统的准 The United States Bureau of Standards is currently investigating a direct comparison of gas flow to mass flow at ambient temperatures with a new continuous closed-loop measurement. At present, although there is no perfect gas flow standard, the accuracy of liquefied gas has been confirmed to be over 0.2% over the past six years. In recent years, research is the standard low-temperature flow liquefaction system. It is believed that when the device is improved, the liquefied gas system is the standard