我国石油液化气大多采用金属球罐储存，由于液化气的特殊性，决定了液化气只能储存在承压密闭的球罐内，因此在液化气计量时不能人工检尺和检温，只能依靠安装在金属球罐上的液位计和温度计作为检尺计量的依据。
Because of the particularity of liquefied petroleum gas, liquefied petroleum gas can only be stored in a confined spherical tank. Therefore, it can not be measured manually, but only by liquid level gauge and thermometer installed on the metal spherical tank.
而液位计和球罐相比，液位计易受环境温度的影响，使得球罐内液化气的温度和液位计内液化气的温度差别很大。因为液体的密度随温度的变化而变化，因此罐内密度和液位计内液化气的密度不一样，引起液位计实际测量值与罐内液位有偏差，从而造成计量误差。
Compared with the spherical tank, the level gauge is vulnerable to environmental temperature, which makes the temperature of liquefied gas in the spherical tank and the temperature of liquefied gas in the level gauge vary greatly. Because the density of liquid varies with temperature, the density of liquefied gas in the tank and the density of liquefied gas in the level gauge are different, which results in the deviation between the actual measurement value of the level gauge and the level in the tank, thus causing the measurement error.