The volume of fluid is a function of fluid temperature and pressure and is the dependent variable, while the mass of fluid is a quantity that does not change with time, space temperature and pressure. As mentioned above, the flow measurement value of commonly used flow meters, such as orifice flow meters, turbine flow meters, Vortex flow meters, electromagnetic flow meters, rotor flow meters, ultrasonic flow meters and elliptical gear flow meters, is the volume flow rate of the fluid. The quantity of fluid involved in scientific research, production process control, quality management, economic accounting, and handover of trade is generally the quality.

Using the above-mentioned flow meter to only measure the volume flow rate of a fluid often fails to meet people's requirements. It is usually necessary to try to obtain the mass flow rate of the fluid. In the past, only after measuring the temperature, pressure, density, volume and other parameters of the fluid, the quality of the fluid could be obtained indirectly through correction, conversion and compensation. This measurement method has many intermediate links and is difficult to ensure and improve the accuracy of mass flow measurement. With the development of modern science and technology, some measurement methods and devices that directly measure mass flow have emerged one after another, thus promoting the progress of flow measurement technology.

Mass Flow MeterIt directly measures the mass flow of the medium passing through the flow meter, and also indirectly measures the density and temperature of the medium. Since the transmitter is an intelligent instrument with a microcontroller as the core, more than a dozen parameters can be derived based on the above three basic quantities for users to use. The mass flow meter is a new generation of flow meter with flexible configuration, powerful functions and high cost performance.

A flow meter that measures the mass flow of a pipeline. When the measured fluid is in a situation where parameters such as pressure and temperature change greatly, if only the volume flow is measured, changes in fluid density will bring about large measurement errors.

In positive displacement flow meters and differential pressure flow meters, the density of the fluid being measured may change by 30%, which will result in a flow error between 30 and 40%. With the improvement of automation level, many production processes have put forward new requirements for flow measurement. The chemical process is controlled by the quality (rather than the volume) of the raw materials. The heating and cooling effects of steam and airflow are also proportional to the mass flow rate. Product quality, cost accounting, and fuel quantity control for aircraft and missiles are strictly controlled. Therefore, the mass flow meter is an important flow measurement instrument.