The flow rate of a fluid refers to the amount of fluid that flows through a certain section of a pipeline per unit time. The quantity of fluid, expressed in volume, is called volumetric flow rate, and in mass, is called mass flow rate. Fluid detection is very important in modern production and life.
The automated instrument used to measure the flow rate of fluids such as liquids, gases, and vapors is called a flow meter.
There are various types of flow meters, which can be classified into multiple types based on different measurement principles. Here are some common types of flow meters and their characteristics:
Elliptical gear flowmeter
Elliptical gear flowmeter
Definition: Elliptical gear flowmeter (also known as displacement flowmeter or gear flowmeter) is a type of volumetric flowmeter with high accuracy.
Working principle: Using a pair of elliptical gears to rotate inside the flowmeter, the measured fluid is continuously divided into individual known volume parts, and the flow rate is measured by measuring the number of times these volume parts are measured.
Features: High measurement accuracy, especially suitable for measuring the flow rate of high viscosity media, but not suitable for fluids containing solid particles.
Waist wheel flowmeter
Definition: The waist wheel flowmeter, also known as the Roots flowmeter, is a type of volumetric flowmeter used for high-precision measurement of flow in pipelines.
Working principle: The measured fluid is divided into individual volume parts by rotating one or two pairs of tangential waist wheels (actually gears with a modulus of 2) inside the flowmeter, and the flow rate is calculated by measuring the number of times these parts are measured.
Characteristics: Commonly used for measuring the flow rate of large-diameter gas, liquid, and steam media.
piston type flowmeter
Definition: A piston flowmeter is an instrument that measures flow by the movement of a piston in a fluid.
Working principle: The mechanical piston flowmeter uses the movement of the piston in the volumetric tube to calculate the flow rate and flow rate of the fluid by measuring the pressure difference required by the piston.
Features: Can measure flow rates from small to large ranges, with high measurement accuracy
Scraper flowmeter
Definition: Scraper flowmeter is an instrument that measures flow by rotating a scraper and rotor.
Working principle: The liquid being measured drives the scraper and rotor to rotate, forming a fixed volume measuring space. The flow rate is calculated based on the amount of liquid in the measuring space.
Features: Unique structure, high measurement accuracy.
Membrane flowmeter
Definition: Membrane flowmeter uses the motion of the membrane to measure the flow rate of a fluid.
Working principle: Gas is introduced into a metering chamber with a certain volume, and the gas is discharged through the repeated movement of the membrane. The flow rate is calculated by counting the number of membrane movements.
Features: Suitable for measuring gases such as gas.
Throttling flowmeter
Definition: A throttling flowmeter calculates flow rate by measuring the differential pressure generated when fluid flows through a throttling device.
Working principle: Install throttling devices (such as orifice plates) in pipelines to generate differential pressure when fluid flows through, which is proportional to the flow rate.
Features: Simple structure, widely used in various fluid measurements.
elbow flow meter
Definition: Bend flowmeter is a differential pressure flowmeter that measures flow rate by utilizing the centrifugal force generated when fluid flows through a bend.
Working principle: The fluid undergoes circular motion inside the bend to generate centrifugal force, and the flow rate is calculated by measuring the pressure difference between the inside and outside of the bend.
Features: Large range ratio, strong adaptability, suitable for measuring high flow rates and large pipe diameters.
Constant velocity pipe flowmeter
Definition: The averaging tube flowmeter is a measuring instrument that uses the pitot tube measurement principle to measure the flow rate by measuring the pressure difference between the dynamic pressure upstream of the baffle and the static pressure downstream. Anuba flowmeter (also known as flute shaped averaging tube flowmeter and Toba tube flowmeter) belongs to this category.
Features: Easy installation, low pressure loss, high strength, not affected by wear and tear, no leakage, it is an ideal product to replace orifice flow meters.
Target flowmeter
Definition: When a fluid flows through a target flowmeter, it impacts the target plate and generates a force proportional to the flow velocity. As the traffic increases, the impact force on the target board increases, resulting in a larger signal output. By measuring the magnitude of this signal, the flow rate of the fluid can be calculated.
Features: Suitable for measuring the flow rate of various fluid media (including liquids, gases, and vapors), and can adapt to different temperature and pressure conditions. The structure is relatively simple, easy to install and maintain.
Rotor flowmeter
Definition: A rotor flowmeter is an instrument that measures fluid flow based on the principle of throttling, also known as a float flowmeter or a variable flow area constant differential pressure flowmeter. By changing the flow area of the fluid to maintain a constant differential pressure between the upper and lower parts of the rotor, the measurement of fluid flow rate can be achieved.
Features: Simple structure, intuitive and easy to read, low pressure loss, wide applicability, and convenient maintenance.
float flowmeter
Definition: A float flowmeter is a common flow measurement device used to measure the velocity or flow rate of liquids or gases. Its working principle is based on the principles of buoyancy balance and resistance balance.
Features: Using the balance relationship between buoyancy and resistance of the float in the fluid to measure flow velocity or flow rate, the working principle is simple and intuitive, suitable for general flow monitoring and control needs.
Orifice flowmeter
Definition: Orifice flowmeter is a common flow measurement instrument that determines fluid flow by measuring the pressure difference inside the pipeline based on Bernoulli’s theorem.
Features: Simple structure, precise and reliable, widely used in flow measurement of various industrial fluid pipelines.
venturi meter
Definition: The Venturi flowmeter is a commonly used device for measuring the flow rate of pressurized pipelines. It belongs to the differential pressure flowmeter and includes three parts: the “contraction section”, “throat section”, and “diffusion section”.
Features: Simple structure, wide range of applicable working conditions, easy real-time monitoring, wear-resistant, long service life, and low maintenance.
Turbine Flowmeter
Definition: Turbine flowmeter is the main type of velocity flowmeter, which uses a multi blade rotor (turbine) to sense the average flow velocity of the fluid and deduce the flow rate or total amount of the instrument.
Features: High precision, among all flow meters, it is the most accurate flow meter; Good repeatability; Compact structure.
Vortex Flowmeter
Overview: Vortex flowmeter is a new type of flowmeter developed based on the Karman vortex principle, mainly used for flow measurement of industrial pipeline media fluids, such as gas, liquid, vapor and other media.
Its characteristics are small pressure loss, large range, high accuracy, and almost unaffected by parameters such as fluid density, pressure, temperature, viscosity, etc. when measuring volumetric flow rate under working conditions.
Electromagnetic Flowmeter
Definition: Electromagnetic flowmeter is a flowmeter based on Faraday’s law of electromagnetic induction, used to measure the volumetric flow rate of conductive liquids.
Features: High measurement accuracy, not affected by changes in fluid density, viscosity, temperature, pressure, and conductivity; Large measurement range, with a range ratio of up to 1:100; There are no mechanical moving parts or throttling components that hinder fluid flow, so there is no pressure loss, wear, blockage, or other issues.
ultrasonic flowmeter
Definition: Ultrasonic flowmeter is an instrument that measures flow by detecting the effect of fluid flow on an ultrasonic beam (or ultrasonic pulse).
Features: Non contact measurement, capable of measuring fluids that are difficult to contact and observe, as well as large pipe flow rates; The measurement accuracy is very high, almost unaffected by parameters such as temperature, pressure, viscosity, density, etc. of the measured fluid; It can measure bidirectional fluids as well as pulsating fluids.
Coriolis Mass Flowmeter
Definition: Coriolis mass flowmeter is an instrument that directly measures the mass flow rate of a fluid, based on the principle of Coriolis force.
Features: High measurement accuracy, capable of measuring various fluids such as gases and liquids; Without temperature or pressure compensation, directly measure mass flow rate; Suitable for measuring fluids with high viscosity and low flow rate.
Thermal gas mass flow meter
Definition: A thermal gas mass flowmeter is an instrument that measures gas flow based on the principle of thermal diffusion.
Features: High measurement accuracy and fast response speed; Capable of measuring small flow rates and corrosive gases; No temperature or pressure compensation is required.
impulse flowmeter
Overview: Impulse flowmeter (also known as water hammer flowmeter) is an instrument that uses the impulse (momentum) generated by the flow of fluid in a pipeline to measure flow rate. Its working principle is similar to the water hammer effect, which calculates the flow rate by measuring the impact force of the fluid on a fixed object.
Gas Roots flowmeter
Definition: Gas Roots flowmeter is a volumetric flowmeter that calculates flow rate by measuring the number of times a fluid passes through a fixed volume.
Features: High measurement accuracy, suitable for gas flow measurement; Simple structure and easy maintenance
Wedge Flow meter
Definition: Wedge flowmeter is a differential pressure flowmeter that calculates flow rate by measuring the pressure difference generated by the fluid before and after the wedge-shaped throttling element.
Features: Wide measurement range, strong adaptability to fluids; Easy installation and simple maintenance.
V-Cone flowmeter
Definition: The V-cone flowmeter is a high-precision differential pressure flowmeter that calculates flow by measuring the pressure difference generated by the fluid before and after the V-cone throttling element.
Features: High measurement accuracy and good repeatability; Low pressure loss and significant energy-saving effect; Suitable for measuring various fluids and working conditions.
The above is a brief introduction to various flow meters, each with its unique working principle and applicable range. In practical applications, suitable flow meters should be selected based on factors such as the properties of the fluid being measured, measurement requirements, and environmental conditions.