How do you measure liquid flow ?

What is flow meter?

The instrument of measuring fluid flow is collectively referred to as the flow meter.
The flowmeter is one of the important instruments in industrial measurement. It is widely applicable to metallurgy, power, coal, chemical, petroleum, transportation, construction, light textiles, food, medicine, agriculture, environmental protection, and people's daily life. It is an important tool for developing industrial and agricultural production, saving energy, improving product quality, and improving economic benefits and management levels. It occupies an important position in the national economy. In order to adapt to various purposes, various types of flowmeters came out one after another. There have been more than 60 kinds flowmeters that have been put into use to measure liquid flow, such as water, diesel, waste water, brine, sea water, fuel, chemical solution.,etc. Most common use flow meters: differential pressure flowmeter, vortex flowmeters, turbine flowmeters,rotameter,digital target flowmeters, electromagnetic flowmeters, ultrasonic flowmeters.

Electromagnetic flow meter for liquid flow measurement

Magnetic flow meter is a normal used flow meter device for liquid measurement, it measure conductive liquid, such as water, salty wastewater, utility water, slurry, pulp, juice , brine , caustic soda, slaked line,NaOH, sulfuric acid, wort.,etc.
Electromagnetic flowmeter has two constructions, remote display and compact display. The flow meter output can easily match the PLC, DCS.,etc to achieve the functions such as recording, control and adjustment . At the same time, the mag meter is possible equipped with the RS-485 /MODBUS communication interface to interconnect with the computer. The working principle of electromagnetic flowmeters is the law of Faraday electromagnetic induction. The conductive liquid flows the magnetic force line in the magnetic field to generate an inductive potential. Expression: E = KBLV, in the formula, B is the magnetic induction strength; L is the distance between the measurement of the electrode; V is the average speed of exercising in the magnetic field in the magnetic field; K is the proportional constant.

Electromagnetic flowmeters are mainly composed of two parts: sensor and converter. The sensor converts the flow of the liquid to the corresponding induction potential. The role of a flow converter is to amplify and convert the millivolvoral voltage signal of the output of the electromagnetic flow sensor and the proportion of the flow into a standard DC current, voltage or pulse signal output that can be received by the industrial instrument.

Advantages of electromagnetic flowmeters are:

• (1) Measuring liquid volume flow with certain conductivity such as solid particles, suspension or acid, alkali, corrosive liquid, aggressive liquid, salt solution, etc. can also do bi-directional liquid flow measurement.
• (2) There are no motion components and streams in the sensor tube, so there is no pressure loss, no mechanical inertia, and the response is very sensitive.
• (3) The measurement range is large, for example 1/2 inch magnetic flow meter, 1” liquid flow meter, 2 inch liquid flow meter, 4 inch liquid meter, 6 inch magnetic flow meter, 8” and DN200 flow meter for liquid.,etc
• (4) The volume flow measured by electromagnetic and flowmeters is actually not affected by liquid density, viscosity, temperature, pressure, and conductivity
• (5) Digital liquid flow meter with 24V or 220V AC or even battery operated liquid flow meter.
• (6) Liquid flow measurement unit can be m3/h, LPH,LPM, CFM,GPM, GPH.,etc

Disadvantages for magnetic flow meters are:

• (1) The electromagnetic flowmeter cannot measure liquid with low conductivity, it can not measure pure water, organic liquid, diesel, fuel .,etc
• (2) Mag liquid flow meter cannot measure gas, vapor and liquid containing more bubbles.
• (3) Magnetic flow meter cannot be used for liquids with very high temperatures.

Liquid Turbine flow meter

Liquid turbine flow meter is a very economical liquid flow metering device; it can measure clean liquid with viscosity less than 40 cps. We often use liquid turbine flow meter to measure water, portable water, refined palm olien, vegetable oil, fuel, diesel, biodesel, kerosene, milk.,etc
Turbine flow meter is composed of turbine, bearing, preamplifier, and display instrument. The liquid flow impact rotor, the turbine rotates, the speed of the turbine changes with the changes of the liquid flow, that is, the liquid flow is large, the speed of the turbine is also large, and then the turbine speed is converted to the electrical pulse of the corresponding frequency. After the front amplifier is amplified, the electronic display is sent to count and display. According to the number of pulse and total pulse number of the unit time, you can find liquid flow rate and cumulative flow.
Features of liquid turbine flow meter are highly accurate, repetitive, no drift, and high -range ratio. The turbine flow meter has high -quality bearing and specially designed diversion films, so it greatly reduces wear and is not sensitive to its peak. The measured liquid cannot contain particles. Solids or particles could cause damage on the turbine flow sensor. Turbine flow sensors has many choices, such as 6mm( 1/4”) low flow liquid flow meter, 10mm, 1/2”, 1”, 2”, DN50 liquid turbine flow meter, 3 inch turbine meter, 4 inch , 6 inch , 8 inch turbine meter and 10 inch turbine flow meter.

Vortex flow meter for liquid volume flow measurement

Vortex flowmeters are mainly used in the flow measurement of industrial pipeline fluids, such as gas, liquid, steam and other media. It can measure liquid like hot water, RO water, DI water, fuel, and diesel. Vortex shedding flow sensor is characterized by small pressure loss, large measurement range, high accuracy, and good repetitiveness. When measured the liquid volume flow of the working conditions, it is almost unprecedentedly affected by parameters such as fluid density, pressure, temperature, and viscosity. Vortex flow sensor has no moving parts, so the liquid measurement performance reliability is high and the maintenance is little needed. The vortex shedding flow instrument parameters can be stable for a long time.

Vortex flow meter is a new type of flowmeter measured according to the principle of Kamen vortex. Because of its good fluids adaptability, it can directly measure the volume flow of steam, air, gas, water, and liquid without the need for temperature and pressure compensation. It is equipped with temperature and pressure sensor to measure the volume flow and mass flow of gas and steam.

Variable area flow meter, also known as (rotor flow meter), it is the volume flow instrument. VA flow meter has long history, and can indicate liquid flow rate without any power supply. Rotameter can measure large range clean liquid, such as water, fuel, chemical solution, chlorhydric acid, Enzyme Solution, Glycerin, Toluene,soy oil,ethyl acetate., etc
The structure of VA flow meter is simple. The flow detection element of the float flowmeter is composed of a vertical cone tube expanded from bottom to top and a float that moves up and down along the cone pipe shaft.
Variable area flowmeters have many advantages such as simple structure, reliable work, small pressure loss, and measured low –flow liquid . Floating flow meters have a wide range of flow range, generally 10: 1. the lowest is 5: 1.The output of the flow detection element is close to linearity.

Ultrasonic flow meter

Ultrasonic flow meter is a speed flow measuring instrument that uses ultrasonic pulse to measure fluid flow. The ultrasonic transmitter converts electrical energy to ultrasonic energy and transmits it to the measured fluid. Ultrasonic flowmeters are generally divided into: inserted sensor ultrasound flowmeters, clamp on ultrasound flowmeters,, etc.
Advantages of ultrasonic flowmeter:
(1) Ultrasonic flow meter is non -contact liquid flow measurement, which is suitable for large tube diameter, large flow measurement, and is not affected by parameters such as the temperature, viscosity, density of the fluid.
(2) The ultrasonic flowmeter can measure various mediums of water or oil.
(3) The energy consumption of ultrasonic flowmeters is very small, which can easily achieve long -term battery power supply.

Disadvantages:

Transit time ultrasonic flow meter can only measure very pure liquid, such as clean water or diesel.

Summary

There are many types of liquid flow measurement methods and instruments. Each product has its specific applicability and its limitations. It is hoped that in the future, liquid flow meter develops more convenient, economical, practical, and applicable to measure the flowmeter of various conditional fluids to better meet the requirements of the industry and benefit humanity.Currently more and more people like to use Coriolis mass flow meter to measure liquid mass flow rate and total mass. It is directly mass flow measurement meter , it has high accuracy and can be used to measure high viscosity liquid , such as resin, heavy oil, glue,paste.,etc