Flowmeter is a kind of equipment that measures the flow of liquid or gas flowing through it, which is widely used in petrochemical, pharmaceutical, energy, environmental protection and other industries. There are various types of flowmeters, and according to the different measurement principles and application scenarios, they can be divided into two categories: volumetric flowmeters and mass flowmeters. The following is a comprehensive introduction to these two types of flowmeters:
Volumetric flowmeter
Volumetric flowmeters are instruments that calculate flow by measuring the volume of fluid passing through a pipe. Common volumetric flowmeters are as follows:
Positive displacement flowmeter: use a fixed volume volume to measure the time of fluid passage, so as to calculate the flow rate. Common types include elliptical gear flowmeters, waist-wheel flowmeters, piston flowmeters and scraper flowmeters. These flowmeters usually have high measurement accuracy and are suitable for applications where accurate measurement is required.
Velocity flowmeter: Calculate the flow rate by measuring the speed of the fluid in the pipe and the cross-sectional area of the pipe. Common velocity flowmeters are turbine flowmeters and vortex flowmeters. The turbine flowmeter uses the pulsating signal generated by the fluid as it rotates through the turbine to measure the flow rate and is suitable for measuring media with high viscosity or containing particles. The vortex flowmeter places a non-streamlined vortex generator in the fluid, and calculates the flow rate according to the proportional relationship between the vortex speed and the fluid speed, which is suitable for large pipe diameter and high pressure drop occasions.
Differential pressure flowmeter: Use the hydrostatic pressure difference and the function between the flow through the fluid to measure the flow. Common differential pressure flowmeters include throttling flowmeters (such as orifice flowmeters, venturi flowmeters) and uniform pitot flowmeters. These flowmeters have simple structure and wide application range, but the measurement accuracy may be affected by the change of fluid physical properties.
Float flowmeter: also known as the rotor flowmeter, the use of fluid flow to the float in the pipe to force, the size of the force is related to the size of the flow. The flow rate is determined by measuring the displacement or rotation speed of the float. Common float flowmeters include glass rotor flowmeters and metal tube float flowmeters, which are suitable for measuring small flow or low viscosity fluids.
Mass flowmeter
Mass flowmeter is an instrument that measures the mass flow of fluid to achieve flow measurement. Common mass flowmeters are as follows:
Thermal mass flowmeter: Measures flow based on the amount of heat lost as the fluid flows through the heating element. When the fluid flows through the heating element, it will take away some heat, and the mass flow rate of the fluid can be calculated by measuring the amount of heat lost. This flowmeter is suitable for measuring the flow rate of gases, especially in situations where a fast response is required.
Oscillating tube mass flowmeter: The use of fluid flowing through the pipe caused by the vibration frequency of the pipe to measure the flow rate. When the fluid flows through the pipe, it will cause the vibration of the pipe, and the mass flow rate of the fluid can be calculated by measuring the change of the vibration frequency. This flowmeter has high measurement accuracy and stability, and is suitable for measuring various fluids.
Coriolis Mass flowmeter: Measures the mass flow of a fluid based on the Coriolis effect. When the fluid flows in the pipe, it will be affected by the Coriolis force, and the mass flow rate of the fluid can be calculated by measuring the size of this force. This flowmeter is characterized by high accuracy, high stability and a wide range of applications, especially for the measurement of high viscosity, high pressure or corrosive fluids.
Ultrasonic flowmeter: Although the ultrasonic flowmeter can also measure the volume flow, its measurement principle is also applicable to the measurement of mass flow (calculated by measuring the density and speed of the fluid). Ultrasonic flowmeter uses ultrasonic propagation speed or time difference in the fluid to measure the flow, with a wide measurement range, high precision, not affected by fluid properties, temperature, pressure and other factors. However, because its price is more expensive, it is usually used for large-scale runoff measurement or high-precision measurement occasions.
Sum up
Different types of flowmeters have different measuring principles and application scenarios. When choosing a flow meter, it is necessary to take into account the specific measurement requirements, fluid properties and installation environment. The volume flowmeter is suitable for measuring the volume flow of fluids, while the mass flowmeter can directly measure the mass flow of fluids, with higher measurement accuracy and stability. In practical applications, the appropriate flowmeter type should be selected according to the specific needs to ensure the accuracy and reliability of the measurement results.
If you want to know more about the flow meter or flow meter selection, please consult the Aister flow meter manufacturer email: sales@aistermeter.com for help.