Difference between mass flow meters and volume flow meters

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This post was last edited by A℡ Li Zixin on 2020-8-15 at 14:07. A mass flow meter can directly measure mass flow rate; it enables dynamic detection of density without the need for compensation, and it can also directly measure volume flow rate. In contrast, a volume flow meter can only measure volume flow rate. If mass flow rate is to be measured, a fixed density value must be specified during configuration, which prevents dynamic density detection and results in lower accuracy. Mass flow meters are expensive but offer higher measurement precision, while volume flow meters are cheaper. However, it is possible to convert between the two. If budget is a concern, it is advisable to choose a volume flow meter and convert the value to mass flow rate using software. Mass flow meters are not affected by temperature or pressure when measuring gases, as they detect density in real time, thus remaining unaffected by the temperature and pressure of the material. Based on the principle of mass conservation, typical processes prefer to use mass flow rate for evaluation; therefore, temperature and pressure compensation is required for all measurement points that are to be assessed, and this approach can be appropriately applied to liquids as well. Therefore, using a mass flow meter is the best option for instrumentation professionals, but the price is unaffordable. Moreover, the requirements for installation are also quite high. Flow meters that utilize the principle of thermal diffusion rely on a technology which offers excellent performance and high reliability under harsh conditions. A thermal mass flow meter has two temperature sensors placed in the medium; one of these sensors is heated to a temperature above the ambient temperature, while the other sensor is used to detect the temperature of the medium. As the flow rate of the medium increases, more heat is carried away by the medium, and the temperature difference between the two temperature sensors changes accordingly with the flow rate of the medium. Based on the proportional relationship between this temperature difference and the flow rate of the medium, it is possible to determine the flow rate Q of the fluid. At present, the vast majority of thermal mass flow meters are used for measuring gases, with only a small number being used to measure the flow rate of tiny liquids.