一、概述密度是指单位体积中物质的质量,它是表征物质特性的一个基本物理量。密度测量不仅在物理学、化学、计量学、海洋学等学科中对各种物质(气、液、固三种状态)性质的研究起着重要的作用,而且国外在石油、化工、冶金、轻工、材料、食品等工业部门中的应用已经十分广泛。尤其是流程密度计已成功地用于对加工的半成品和产品的质量和数量进行连续控制和闭环控制;通过密度测量以控制连续调合工序中各组成部分的比例。随着精确计 I. INTRODUCTION Density refers to the mass of a substance in a unit volume. It is a basic physical quantity that characterizes a substance. Density measurement not only plays an important role in the study of the properties of various substances (gas, liquid and solid) in physics, chemistry, metrology, oceanography and other disciplines, but also in foreign countries in the petroleum, chemical, metallurgy, light Workers, materials, food and other industrial sectors has been very wide range of applications. In particular, flowmeters have been used successfully for the continuous control and closed-loop control of the quality and quantity of processed semifinished products and products; the density measurement has been used to control the proportions of the components in the continuous blending process. With precise meter