There are many kinds of flow measurement methods and instruments, and many classification methods. There are 60 kinds of flow meters available for industrial use before 2011. The reason why there are so many kinds of flowmeters is that there is no flowmeter suitable for any fluid, any range, any flowing state and any operating conditions. But with the progress of the times, in the era of the explosion of science and technology, a new product, mass flowmeter, has finally emerged. The mass flowmeter is suitable for any fluid, any range, any flowing state and any term. What use conditions, but the price is more expensive, can not be popularized in all industries.
There are more than 60 old flow meters, each of which has its specific applicability and limitations. There are two categories of closed pipeline and open channel according to the object of measurement. According to the purpose of measurement, it can be divided into total measurement and flow measurement, whose instruments are called total meter and flow meter respectively.