What is a velocity flow meter?

Velocity Flow Meter is a flow meter that obtains flow parameters by directly measuring the flow rate of the full pipe in the closed pipe section. The flow rate can be calculated by measuring the velocity of the flow by using a velocity flow meter. Velocity flow meters mainly include-electromagnetic, ultrasonic, turbine, vortex, precessing vortex, rotor, etc.

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Flow Meter Types

There are many types of flow meters. Basically, there are the following types of flow meters

Why are there so many types of flow meters? This starts with the working conditions of the factory. The three elements of working conditions, medium, temperature, pressure, and conditions are ever-changing. Create thousands of types of working conditions. It requires different principles and different types of flow meters.

Extended reading: Integral DP Flow Meter|Gas, liquid, steam|Compact structure

Velocity Flow Meter Types

Electromagnetic flowmeter

A magnetic Flow Meter is a flow meter that measures the flow of conductive fluids. Abbreviated as EMF, also called Electromagnetic flowmeters. It is a kind of Volumetric flow meter. A magnetic flow meter measures the velocity of conductive liquids moving through a pipe or conduit. In the wastewater treatment industry, a Magnetic Flow Meter is the best flow meter choice.

Advantages of using Electromagnetic Flow Meters.

• High precision and stability
• Self-check
• Two-way measurement
• No pressure loss
• No moving parts
• May be for sanitary purposes
• Large size available
• Dirty liquid and mixed fructose are ok

Disadvantages of using Magnetic Flow Meters

• Can not be used to measure gas, steam and liquids containing a lot of gas;
• Cannot be used to measure liquid media with very low conductivity.
• Cannot be used to measure high temperature media. At present, it is restricted by the lining material and electrical insulation material of the measuring tube of the electromagnetic flowmeter for general industry;
• The electromagnetic flowmeter is easily affected by external electromagnetic interference.

Ultrasonic Flow Meter

The ultrasonic flow meter measures the liquid flow rate quickly and effectively. There are two types of ultrasonic flowmeter technology: Doppler frequency shift and transit time.

Transit time ultrasonic flow meter is most suitable for measuring the flow of cleaning liquid. Therefore, it is the most popular type of ultrasonic meter.

Doppler ultrasonic flow meter can measure the frequency difference of sound waves reflected from bubbles or particles in the airflow. It is suitable for aerated or dirty liquids.

Extended reading: Ultrasonic flow detectors types

Advantages of Ultrasonic Flow Meters

• Ultrasonic flowmeter is a non-contact measuring instrument, which can be used to measure the flow of fluids and large pipe diameters that are not easy to contact and observe. It does not change the fluid flow state, does not produce pressure loss, and is easy to install.
• It can measure the flow of strong corrosive media and non-conductive media.
• Ultrasonic flow meters have a large measuring range, with pipe diameters ranging from 20mm to 6m.
• Ultrasonic flowmeter can measure the flow of various liquids and sewage.
• The volume flow measured by the ultrasonic flowmeter is not affected by the temperature, pressure, viscosity and density of the fluid being measured. It can be made into fixed and portable forms.

Disadvantages of Ultrasonic Flow Meters

• The temperature measurement range of an ultrasonic flowmeter is not high, and generally it can only measure fluids with a temperature lower than 200°C.
• Poor anti-interference ability. It is susceptible to the interference of bubbles, fouling, pumps and other sound sources mixed with ultrasonic noise, which affects the measurement accuracy.
• The straight pipe section has strict requirements, 20D in the front and 5D in the back. Otherwise, the dispersion is poor and the measurement accuracy is low.
• Uncertainty in installation will bring large errors to flow measurement.
• The fouling of the measuring pipe will seriously affect the accuracy of the measurement and bring about significant measurement errors. Even in severe cases, the meter has no flow display.
• Reliability and accuracy are not high (generally around 1.0-2.5), and repeatability is poor.

Extended reading: Make Ultrasonic Open Channel Flow Meter Work for You

Turbine flow meter

Turbine flow meters are velocity flow meters, also called impeller flow meters. Can be used to measure the instantaneous flow and cumulative flow of liquids and gases.

Turbine flowmeters are widely used in flow measurement: petroleum, organic liquids, inorganic liquids, liquefied gas, natural gas, coal gas, and cryogenic fluids. Turbine flowmeter signals can be divided into pulse signals or current signals (4-20mA). It is suitable for use with secondary display, PLC, DCS, and other computer control systems.

Turbine Meter Advantages

• The cost is moderate.
• Very good at clean, low viscosity fluids of moderate velocity and a steady rate.
• Turndown is very good as it can read very low compared to the greatest flow.
• They are reliable if put in a clean fluid especially if it has some lubricity.
• AGA and API approved for custody transfers.
• They do cause some pressure drop where that may be a factor such as gravity flows.
• High accuracy. Among all flowmeters, it is the most accurate flowmeter.
• No zero drift, good anti-interference ability.
• High accuracy. Among all flowmeters, it is the most accurate flowmeter.
• No zero drift, good anti-interference ability.

Turbine Meter Disadvantages

• Not reliable for steam.
• Bearings wear out.
• Requires constant backpressure to prevent cavitation.
• Accuracy adversely affected by bubbles in liquids.
• Turbine meters can be used with clean liquids and gases only (may need to install a strainer upstream to prevent damage from particulates).
• Not applicable for measuring corrosive fluids.
• May not function properly with high viscosity fluids where the flow profile is laminar.
• Cannot maintain calibration characteristics for a long time.

Extended reading: Turbine Insertion Flow Meter for Large Diameter Pipeline

Vortex flowmeter

A vortex flow meter is also called Vortex shedding flow meter. Vortex Flow Meter is suitable for flow measurement of steam and various liquids and gases.

The vortex flowmeter is a volume flow meter that measures the volume flow of gas, steam, or liquid, the volume flow of standard conditions, or the mass flow of gas, steam, or liquid-based on the Karman vortex principle. When the fluid flows through the dust collector rod of the vortex flowmeter, a vortex is formed. The frequency of vortex shedding is proportional to the fluid velocity. Temperature and pressure compensation can be configured.

Extended reading: Vortex Steam Flow Meter

Advantages of vortex flowmeter

• The pressure loss is small, about 1/4 to 1/2 of the throttling differential pressure flowmeter.
• Output a pulse signal proportional to the flow rate, without zero drift.
• The structure is simple, firm, easy to install and maintain. There is no need for pressure guiding pipe and three-valve group, etc., reducing leakage, blockage and freezing. The measuring element has simple structure, reliable performance and long service life.
• The accuracy is high, generally ±(1～1.5)%R.
• The measuring range is wide, the vortex flowmeter with a reasonable caliber is determined, and the range can reach 20:1.
• Within a certain Reynolds number range, the output frequency of the orifice flowmeter is not affected by the physical properties (density, viscosity) and composition of the fluid, that is, the meter coefficient is only related to the shape and size of the vortex generator and the pipeline.
• The volume flow of the vortex flowmeter is not affected by thermal parameters such as the temperature, pressure, density or viscosity of the fluid being measured. Generally, no separate calibration is required. It can measure the flow of liquid, gas or steam.

Understanding the relationship between Flow Rate and Pressure may help you calculate mass or volume flow.

Disadvantages of vortex flowmeter

(1) The volume flow of the vortex flowmeter is not affected by the temperature, pressure, density and other thermal parameters of the measured fluid, but the final measurement result of liquid or steam should be the mass flow. For gas, the final measurement result Should be the standard volume flow. Both the mass flow rate or the standard volume flow rate must be converted by fluid density, and changes in fluid density caused by changes in fluid working conditions must be considered.

(2) The main factors that cause flow measurement errors are: measurement errors caused by uneven flow velocity of the pipeline; the density of the medium when the fluid working condition changes cannot be accurately determined; the wet saturated steam is assumed to be dry saturated steam for measurement. If these errors are not limited or eliminated, the total measurement error of the vortex flowmeter will be very large.

(3) Poor vibration resistance. External vibration will cause measurement errors of the vortex flowmeter, or even fail to work normally. The high-velocity impact of the channel fluid will cause additional vibration to the cantilever of the vortex generator, which will reduce the measurement accuracy. The influence of large pipe diameter is more obvious.

(4) Poor adaptability to measuring dirty media. The generating body of the vortex flowmeter is very easy to be dirty by the medium or entangled by the dirt, and the change of the geometric body size has a great influence on the measurement accuracy.

(5) High requirements for straight pipe sections. Experts pointed out that the straight pipe section of the vortex flowmeter must ensure the front 40D and the 20D to meet the measurement requirements.

(6) Poor temperature resistance. Vortex flowmeters generally can only measure the fluid flow of media below 300°C.

Extended Reading: Collection of Industrial Insertion Flowmeter Type

More about Different Types of Flowmeters – Technical and Application Analysis.

Area Velocity Flow Meter

Variable area flow meters are flow meters in which the fluid must pass through a restricted area. Because the flow cross-sectional area of ​​the flow meter varies with the height of the float. Therefore, this type of flowmeter is called variable area flowmeter or equal pressure drop flowmeter. The typical instrument of this type of flowmeter is a rotameter. This is in contrast to flow meters such as orifice plates and venturi tubes, where the area of ​​the flow element remains fixed. Variable area flowmeters can measure of gas and fluid flow.

Variable area flow meter advantages and disadvantages

• The advantages of the variable area flow meter are simple structure and easy testing, suitable for measuring small flow.
• The disadvantage of variable area flow meter is that it is easily affected by factors such as fluid density, pressure, and viscosity. When testing the flue gas flow, because the flue gas contains dust, the area flowmeter cannot be used.

Extended reading: Fuel Flow Meter for Boat-Selection & Application

Mechanical Flow Meter

Mechanical flow meters are a type of flow meters that use arrangement moving parts to measure flow. The fluid passes through a series of gears or chambers (positive displacement or PD) or through a rotating turbine or rotor. Mechanical flowmeter is different from electromagnetic and ultrasonic in principle. Mechanical flow meters easily monitor liquid flow rates for water, fuels, viscous fluids and more.

Guess you like: What is Reynolds number?

Extended reading: Mechanical flow meter types

Extended Reading: Inline Ultrasonic Flow Meter

A wide variety of Velocity Flow Meters options are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of Velocity Flow Meters, located in China.

The top supplying country is China (Mainland), which supply 100% of the Velocity Flow Meters respectively.

Sino-Inst sells through a mature distribution network that reaches all 50 states and 30 countries worldwide. Velocity Flow Meters products are most popular in Domestic Market, Southeast Asia, and Mid East.

You can ensure product safety by selecting from certified suppliers, with ISO9001, ISO14001 certification.

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KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects.

Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.

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What is Strap on Ultrasonic Flow Meters?

Strap on Ultrasonic Flow Meter is also often called Clamp On Type Flow Meter. The unique feature of Strap on Ultrasonic Flow Meter is that the sensor does not need to be in contact with the medium, which is different from other flow meters.

• Clamp on type, No need to cut the pipe or do any other changes.
• No professional product knowledge required, installation and measurement can be done based on the guide.
• No moving parts or pressure changes involved, installation can be done without stop provide.

Get a Quote Ultrasonic Flow Meters

Featured Strap on Ultrasonic Flow Meters

Strap on Ultrasonic Flow Meter Working Principle

The strap-on ultrasonic flow meters supplied by Sino-Inst are based on the working principle of the time difference method.

Transit Time Ultrasonic Flow Meter adopts the measurement principle of the time difference method. It uses the ultrasonic wave emitted by the sensor to propagate in the flowing fluid. The sound wave propagation speed in the downstream direction will increase, and the backward direction will decrease. In the same propagation distance, there will be different transmission times. According to the difference between the transmission time and the measured The relationship between fluid velocity measures the fluid velocity.

The flow rate of the fluid is different in different positions in the tube. The flow rate in the center of the tube is faster than the flow rate near the wall of the tube. The flow velocity distribution of the fluid in the pipeline can be represented by the flow velocity cross-sectional distribution diagram.

By setting the flowmeter and considering the cross-sectional distribution of the flow velocity, the average flow velocity can be calculated. Then the volume flow of the fluid can be obtained according to the cross-sectional area of the pipe.

Notes:
V measure fluid velocity
M ultrasonic reflection times
D pipe diameter
θ The angle between the ultrasonic signal and the fluid
T up The time when the downstream sensor transmits the signal to the upstream
T down Time from upstream sensor to downstream
ΔT = T up – T down

Guess You’ll Like: Ultrasonic flow meters types & technical guide

Strap on Ultrasonic Flow Meters Application

Sino-Inst concentrates on the development of flow measurement technology. The products serve real-time flow measurement and participation process control in the production process. The main customer industries are the chemical production process, fine chemical production, cleaning industry, beverage industry, etc.

With the world’s most advanced time measurement chip (time resolution of 50ps), Sino-Inst has developed a series of straps on ultrasonic flow meters.

It takes only 2-3 minutes to complete the whole process from installation to measurement. It also adopts the current popular OLED display, which makes it easy to read in low light conditions.

Strap on Ultrasonic Flow Meters is widely used in the production process flow measurement and monitoring. The application of the product continuously and effectively controls the flow of the fluid, so as to improve the yield of the product and even save the input of the personnel, bringing benefits to the production enterprise.

Strap on Ultrasonic Flow Meters can meet different pipe requirements: stainless steel pipe, carbon steel pipe, copper pipe, plastic pipe(PVC, PVDF, PPR, PPH, HDPE, etc.).

Extended reading: non contact flow meter

Strap on Ultrasonic Flow Meters also satisfies different clean fluid measurements: various acids, alcohols, chemical solvents, alcohol, beverage water, Coca-Cola water, etc. Strap on Ultrasonic Flow Meters output signal, such as 4-20mA. The flow signal can be connected to a paperless recorder. Carry out multi-channel flow signal monitoring. What Is A Paperless Recorder?

Extended reading: Fluid flow meter types

Extended reading: Battery operated electromagnetic flow meter-GRPS-new irrigation water flow meter

Installation Guidelines

Frequently
Asked
Questions

Help Center

How accurate are clamp-on flow meters?

Ultrasonic Clamp-on Flow Meter is composed of an integrated host and external clamp-on sensors. Clamp-on Flow Sensors are available at room temperature and high temperature.

High Accuracy measuring:

Linearity: better than 0.5%, Repeatability: better than 0.2%, Accuracy: better than ±1% 

Extended reading: Ultrasonic flow detectors types

What are the different types of ultrasonic flow meters?

Classification of ultrasonic flowmeters.

1. According to the measurement principle

(1) Time difference method ultrasonic flowmeter;
(2) Frequency difference method ultrasonic flowmeter;
(3) Phase difference method ultrasonic flowmeter;
(4) Doppler ultrasonic flowmeter;
(5) Ultrasonic flowmeters for partially full pipes and river channels that combine liquid level measurement and average flow velocity measurement.

More about Different Types of Flowmeters – Technical and Application Analysis

2. According to the way of use

(1) Portable ultrasonic flowmeter;
(2) Fixed (standard pipe section) ultrasonic flowmeter.

3. According to the installation method of the transducer

(1) Standard pipe section ultrasonic flowmeter;
(2) Clip-on ultrasonic flowmeter;
(3) On-site hole-opening plug-in ultrasonic flowmeter.

Read more: Insertion Type Ultrasonic Flow Meter Applications

4. According to whether the transducer is in contact with the fluid

(1) Immersion (contact) ultrasonic flowmeter;
(2) Non-invasive (non-contact) ultrasonic flowmeter.

5. According to the nature of the measured fluid

(1) Liquid ultrasonic flowmeter;
(2) Gas ultrasonic flowmeter.

6. According to the number of transducer channels

(1) Mono ultrasonic flowmeter;
(2) Two-channel ultrasonic flowmeter;
(3) Multi-channel ultrasonic flowmeter.

Extended reading: High Pressure Rotameter for Liquids/gas-Upto 25 Mpa

What is the main function of the ultrasonic Doppler meter?

Doppler ultrasonic flowmeter is widely used in industry, water conservancy, irrigation, and other industries. It is suitable for flow measurement of full pipe, partial pipe, open channel, etc.

(1) Branch channel flow monitoring (narrow channel)

Water distribution in the irrigation area requires real-time monitoring of the branch canal water level and flow. The traditional method is to measure the water level method. This method has high civil construction costs. The monitoring efficiency is low. The measurement accuracy is not enough.

Doppler ultrasonic flowmeter solves the problem of water measurement in-branch canals in irrigation areas.

Just fix the probe at the bottom of the channel. The device automatically measures the channel water level, flow area, and flow rate in real-time and calculates the instantaneous flow and cumulative flow. The flow rate measurement accuracy can reach ±1%+±1cm/s.

(2) Main channel flow monitoring (wide channel)

The difference between the main canal and the branch canal is that the width of the main canal is wider. Therefore, it is necessary to install multiple sets of Doppler ultrasonic flowmeters to accurately measure the flow velocity at different positions of the section during the operation.

The flow of the entire channel can be accurately measured through the integration method. This method is also applicable to some wide rivers.

(3) Monitoring of urban drainage pipeline flow

With the implementation of smart municipal administration, in order to monitor the operation of urban drainage pipe networks, municipal departments need to monitor the water level and flow of drainage pipes in real-time.

Through the analysis of the water level and flow data, the problems of siltation, overload, overflow, and abnormal water infiltration in the pipeline can be distinguished.

Extended reading: Make Ultrasonic Open Channel Flow Meter Work for You

Extended reading: metal tube flow meter

Sino-Inst, Manufacturer for Strap on Ultrasonic Flow Meters. It can measure a single sound-conducting liquid medium of DN 5—6000mm. It can measure even liquids such as water, seawater, oil, and slurry.

Sino-Inst’s Strap on Ultrasonic Flow Meters, made in China, Having good Quality, With better price. Our flow measurement instruments are widely used in China, India, Pakistan, the US, and other countries.

KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects.

Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.

drurylandetheatre.com

What is 4-20ma Flow Meter?

4-20mA Flow Meters are those flow meters with 4-20mA current signal output function. The signal current of general instruments is 4-20mA. This means that the minimum current is 4mA and the maximum current is 20mA. Our commonly used electromagnetic flowmeters, turbine flowmeters, mass flowmeters, gas flowmeters, etc. all have the function of 4-20mA signal output.

Get a Quote Digital Flow Meters

What is a 4-20mA Output？

The signal current of general instruments is 4-20mA, which means that the minimum current is 4mA and the maximum current is 20mA.

The industry generally needs to measure various non-electrical physical quantities. For example, temperature, pressure, speed, angle, etc. They all need to be converted into analog electrical signals before they can be transmitted to the control room or display equipment hundreds of meters away. This device that converts physical quantities into electrical signals is called a transmitter. The most widely used in the industry is to use 4-20mA current to transmit analog quantities.

In the industrial field, to complete signal conditioning and long-term transmission, the following problems will occur:

1. Since the transmitted signal is a voltage signal, the transmission cable will be interfered by noise;
2. The distributed resistance of the transmission cable will produce a voltage drop;
3. How to provide the working voltage of the instrumentation amplifier in the field is also a problem.

In order to solve the above problems and avoid the influence of related noise, we will use current to transmit signals. Because the current is not sensitive to noise.

The 4-20mA current loop uses 4mA to represent the zero signal. Use 20mA to represent the full scale of the signal. The signals lower than 4mA and higher than 20mA are used for various fault alarms.

Why Choose 4-20mA Instead of 0-20mA for the Flowmeter?

Many people will certainly ask: Why choose 4-20mA instead of 0-20mA?
Very simple, if 0 is the smallest, then the open circuit fault will not be detected!

So, why is it 4mA?
During normal operation, the current signal will not be lower than 4mA.
When the transmission cable is broken due to a fault, the loop current drops to zero. 2mA is often used as the disconnection alarm value.
There are two reasons. One reason is to avoid interference. Another reason is that a two-wire system is used at 4-20mA. That is, the two wires are the signal wires. It is also a power cord. And 4mA is to provide the static working current of the circuit to the sensor.

Extended Reading: Mechanical flow meter for diesel

How Does This 4-20mA Control Loop Work?

4-20mA constitutes the basic elements:

• 24V power supply
• The transmitter controls the 4-20mA signal to change in proportion to the process variable
• The indicator converts the 4-20mA signal into the corresponding process variable
• Indicator or controller I/O input resistance 250Ω shunt generates 1-5V input signal (Ohm’s law: voltage = current * resistance, 4-20 mA X 250 ohms = 1-5V)

Usually:

1. They convert the temperature signal of the thermocouple or thermal resistance sensor into a 4-20mA signal and then output;
2. The controller then translates 4-20mA into a specific temperature value;
3. Based on this temperature value. The control loop realizes the control of the process terminal control element.

Similarly, the pressure transmitter is in the control loop. Usually used to measure the pressure value of the process medium:

1) The sensor senses pressure. The transmitter converts the signal into 4-20mA signal;
2) The controller then reversely translates the 4-20mA signal into a pressure value;
3) The controller is based on the pressure value. Send instructions to the valve. Control valve opening to realize safety valve control. Ensure that the container does not generate dangerous pressure.

Extended reading: Orifice Plate Flow Meter

Water Flow Meter 4-20ma Output

A Digital Water flow meter is a flow meter that can display the water flow rate, and have the output for the flow rate. Like 4-20mA output, HART, RS 485, and so on. Digital Water Flow Meter is also called Electronic Water Flow Meter. Digital Water Flow Meter is widely used in industrial water and household water measurement. Most of the Sino-Inst flow meters are digital water flow meters. Like the electromagnetic flowmeter, Portable ultrasonic flow meter, Turbine flow meter…..

No matter which WaterFlow Meters you choose. The signal output by WaterFlow Meters, such as 4-20mA. The flow signal can be connected to a paperless recorder. Carry out multi-channel flow signal monitoring.

Read More About: Paperless Recorder Working Principle

Flow Meter with Analog Output

The analog flow meter is a flowmeter with the analog output signal. Analog output is a common function of flow meters. The analog signal is mainly used to output the flow signal to the next control system.

The analog signal refers to the continuous signal of the information parameter in a given range. The characteristic quantity of the information of the analog signal can be transformed into an arbitrary numerical signal in an instant. In the process of transmitting analog signals, the information signals need to be converted into electric wave signals, which are then transmitted through wired or wireless methods.

Analog signal: poor confidentiality, weak anti-interference ability.

Digital signal: strong anti-interference ability and good communication confidentiality.

Read more about Analog Flow Meters.

Turbine Digital Flow Meter

Turbine flow meters are velocity flow meters, also called impeller flow meters. Can be used to measure the instantaneous flow and cumulative flow of liquids and gases.

Turbine flowmeters are widely used in flow measurement: petroleum, organic liquids, inorganic liquids, liquefied gas, natural gas, coal gas, and cryogenic fluids. Turbine flowmeter signals can be divided into pulse signals or current signals (4-20mA). It is suitable for use with secondary display, PLC, DCS, and other computer control systems.

Turbine Flow Meter reference price: USD 200-1700/pc.

4-20ma Air Flow Meter

A digital air flow meter refers to a flow meter that can accurately measure air or compressed air inline. Industrial Digital air flow meters can be divided into mass flow meters or volume flow meters.

Read more about Digital air flow meters.

Related Blogs

Looking for 4-20ma flow meters? The flow meter is a fast, accurate, and reliable permanent linear motion. In Sino-Inst, you can also find other good deals on measurement and analysis instruments and tools! Keep an eye out for promotions and deals, so you get a big saving of 4 20ma flow meters. You can shop for 4 20ma flow meters at low prices.

Extended reading: How to convert a 4-20mA to 0-10V /1-5V signal?

There is a wide variety of 4-20ma flow meter items you can buy, such as turbine water flow meters, ultrasonic flowmeters. Common materials used for 4 20ma flow meters are stainless steel and carbon steel.

Sino-Inst offers over 50 4-20ma flow meters for flow measurement. About 50% of these are differential pressure flow meters, 40% are the liquid flow sensor, and 20% are Ultrasonic Level Transmitter and mass flow meters.

A wide variety of flow meters options are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of flow measurement instrumentation, located in China.

Request a Quote

KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects.

Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.

drurylandetheatre.com

what is a venturi tube?

The Venturi Tube is a tubular device commonly used to measure fluid flow rates. It is based on a physical principle, the Venturi effect. This effect states that as a fluid passes through a narrow section of a pipe, its velocity increases and its pressure decreases. The design of the Venturi Tube takes advantage of this principle, with a gradually narrowing entrance and a subsequently expanding exit. As fluid enters the narrowed portion of the venturi, it accelerates, causing the pressure to decrease. This change in pressure can be measured by pressure measuring points on the pipe wall and calculated to determine the flow rate of the fluid.

Venturi Tube is a common flow measurement tool in industry. It is widely used in the measurement of various fluids because of its simple structure, good stability and high accuracy.

Get a Quote More Flowmeters

Venturi Effect

The Venturi effect describes the increase in velocity and decrease in pressure as a fluid passes through a narrow section of a pipe. When fluid enters a narrow section of a pipe, the flow rate increases and the corresponding pressure decreases. This effect was discovered by Italian physicist Giovanni Battista Venturi, hence its name.

This effect can be explained by Bernoulli’s equation. This equation is a fundamental law of fluid dynamics. Show that in an incompressible fluid without viscosity, the energy of the fluid along the streamline is conserved.

P + 1/2 ρ v^2 + ρ gh = constant

P represents the pressure of the fluid
ρ is the density of the fluid
v is the velocity of the fluid
g is the acceleration due to gravity
h is the height of the fluid

In practical applications, the Venturi effect allows the venturi tube to be used to measure the velocity of a fluid in a pipe, since the velocity of the fluid is proportional to the pressure difference in the pipe.

The Venturi effect is not only used in measurement tools, but is also widely used in many fields such as aircraft wing design, chimney airflow design, and underwater piping systems. It is a very important principle in fluid mechanics and has a profound impact on many branches of engineering and physics.

Venturi tube working principle

The venturi tube is composed of the following parts:

1. Entrance section: a short cylindrical section with a diameter of D;
2. Contracting section: the shape is a tapered tube, the cone angle is about 21°±2°;
3. Throat: a short straight pipe section with a diameter of about 1/3～1/4D and a length equal to the pipe diameter;
4. Diffusion section: Conical tube with a cone angle of 8°～15°. There is a pressure measuring ring at 0.25-0.75D from the end of the inlet section, with at least 4 pressure measuring holes on it, and the pressure ring leads to the pressure gauge.

In addition, in the center of the throat, there is also a multi-channel pressure measuring ring leading to the pressure gauge. The pressure difference between the inlet section and the smallest section (that is, the throat section) can be measured through the scale of the pressure gauge or the automatic recorder.

Suppose the average velocity, average pressure, and cross-sectional area at the entrance section and the throat are v1, p1, S1, and v2, p2, S2; the fluid density is ρ.

Applying Bernoulli’s theorem and the continuity equation and noting that the streamlines of average motion are of the same height, we can get:

The formula for calculating the flow rate Q can be obtained:

After knowing ρ, S1, S2 and measuring p1-p2, the flow rate Q can be obtained according to the above formula.

The main advantage of the venturi tube is its simplicity of installation. Secondly, due to its diffusion section, the fluid gradually decelerates, reducing the turbulence (see turbulence). Therefore, the pressure head loss is small, no more than 10-20% of the pressure difference between the inlet and the throat.

Venturi tube design

According to the manufacturing process and use, the venturi is divided into standard venturi, general venturi, venturi flow tube, small diameter venturi, rectangular venturi, and other structures. The detailed structure is as follows:

Structure type:

The standard (classic) Venturi tube is composed of an inlet cylindrical section A, a conical contraction section B, a cylindrical throat C, and a conical diffusion section E. The diameter of the cylinder section A is D, and its length is equal to D; the contraction section B is conical and has an included angle of 21º±1º; the throat C is a circular cylinder section with a diameter d, and its length is equal to d; the divergent section E It has a conical shape with a spread angle of 7º～ 15º.

The general-purpose venturi, like the standard venturi, is composed of an inlet cylindrical section A, a conical contraction section B, a cylindrical throat C, and a conical diffusion section E.

The general-purpose venturi adopts the method of changing the contraction angle of the standard venturi and the length of the diffusion section to make it have the advantages of venturi, greatly shortening the length of the body, and effectively reducing the pressure loss.

The Venturi flow tube is also composed of an inlet cylindrical section A, a conical contraction section B, a cylindrical throat C, and a conical diffusion section E. The Venturi flow tube adopts a special pressure method to make it widely used in the flow measurement of dirty media and mixed-phase flow.

The small diameter venturi is composed of an inlet cylindrical section A, a conical contraction section B, a cylindrical throat C, and a conical diffusion section E. The small diameter venturi adopts an integrated mechanical processing method to measure the fluid flow of small diameters. At the same time, it can use a variety of materials to meet the requirements of the on-site working conditions and can meet various connection methods such as welding, flange connection, and threaded connection.

The rectangular venturi is composed of an inlet cylindrical section A, a conical contraction section B, a cylindrical throat C, and a conical diffusion section E. Main technical parameters of rectangular venturi:

• Nominal diameter: DN=1.13×(WH)0.5≤6000mm
• Inlet diameter ratio W/H: 0.5≤W/H≤2.0
• Throat diameter ratio w/h: 0.5≤w/h≤2.0
• Equivalent β value: 0.44≤β=(w/h)0.5/(W/H)0.5≤0.74
• Reynolds number range: 2×105≤ReD≤2×107
• Accuracy: ±1%
• Repeatability: ±1%
• Working pressure: 0～25Mpa
• Working temperature: -100℃～500℃
• Turndown ratio: 1:10

Rectangular venturi is mainly used in power plant air supply and suction, heating furnace air supply, and suction occasions.

Extended reading: Pitot Tube vs Venturi Meter

How does a Venturi tube measure flow?

Using the Venturi Effect to measure flow, the simple steps are as follows:

• Install the venturi: First install the venturi in the pipe where the flow is to be measured.
• Connect the differential pressure sensor:
  • Install a pressure sensor at the wide end and the narrow end of the venturi tube. These sensors measure the pressure difference between the two ends, which is directly related to the fluid velocity.
• Reading the pressure difference:
  • As fluid passes through a venturi, its velocity increases in the narrow section, causing the pressure there to drop. The differential pressure sensor reads the pressure values at the wide end and narrow end and calculates the pressure difference between the two.
• Calculate flow velocity:
  • Use Bernoulli’s equation and continuity equation to calculate the velocity of the fluid. v = sqrt(2(P1 – P2)/ρ). where P1 is the pressure at the wide end, P2 is the pressure at the narrow end, and ρ is the density of the fluid.
• Determine the flow rate:
  • Calculate the flow rate (Q), the formula is: Q = A2 × v. where A2 is the cross-sectional area of the narrow portion of the venturi tube and v is the fluid velocity calculated in the previous step.
• Recording and monitoring: Continuously monitor pressure difference and flow, and record data for analysis or monitoring system status.

Venturi tube flow meter

A Venturi flow meter is a differential pressure flowmeter. The Venturi flow meter is a combination of a Venturi tube, a differential pressure transmitter, and a valve block. It is often used to measure the flow of pressure pipes.

Venturi flow meters are often used to measure the flow of fluids such as air, natural gas, coal gas, and water. It includes three parts: “constriction”, “throat” and “diffusion”. Install on the pipe where the flow rate needs to be measured.

Venturi flowmeter is a new generation of differential pressure flow measuring instruments. The basic measurement principle is a flow measurement method based on the law of conservation of energy-Berlier equation and flows continuity equation.

The throttling process of fluid flowing through the inner venturi tube is basically similar to the throttling process of fluid flowing through a classic venturi tube and an annular orifice plate.

Extended reading: Fluid flow meter types

Venturi flow meters types:

Classic Venturi:

It is applied to the flow measurement of various media and has the characteristics of small permanent pressure loss, the required long and short front and rear straight pipe sections, and long service life.

Casing type venturi:

It is mainly used in the flow measurement and control of various large-caliber and high-pressure or dangerous media in the petrochemical industry.

Venturi nozzle:

It is suitable for the measurement occasions of various media. It has the characteristics of small permanent pressure loss, a short length of the front and rear straight pipes required, and long life. The installation length of the body is shorter than that of the classic venturi.

Extended reading​: What is a flow nozzle?

Read more about: 5 Factors Affecting Pressure Drop

Venturi tube application

Since its development, venturi products have been successfully applied to the measurement of high-humidity natural gas, low-pressure dirty biogas, coke oven gas, gas, steam, hot water, high-temperature hot kerosene, etc., And the practical application range is rapidly expanding.

Besides, the venturi tube has a unique measurement advantage, for measuring conditions such as long straight pipe installation conditions, special high temperature, high pressure, strong corrosive and dirty media, and non-single phase flow measurement.

Of course, in the sewage and wastewater treatment industry, in addition to venturi flowmeters, electromagnetic flowmeters are also the first consideration for many users.
For example, if you need to measure the flow of wastewater in a 2-inch pipe. Then you can refer to Magnetic Flow Meters Guides.

Extended reading: Hot Water Flow Meters Improve Heating-Boiler System

Related blog

Related DP flowmeters

Sino-Inst offers over 50 flow meter products. About 50% of these are differential pressure flow meters (like the Orifice flowmeter), 40% are Magnetic Flow Meters, and 40% are Thermal mass flowmeters.

A wide variety of Annubar flow meter options are available to you, such as free samples, paid samples. 

Sino-Inst is a globally recognized supplier and manufacturer of flow measurement instrumentation, located in China.

The top supplying country is China (Mainland), which supply 100% of the turbine flow meter respectively. Sino-Inst sells through a mature distribution network that reaches all 50 states and 30 countries worldwide.

You can ensure product safety by selecting from certified suppliers, with ISO9001, ISO14001 certification.

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KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects.

Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.

drurylandetheatre.com

You may have heard of flow transmitters and flow meters. Are flow transmitter and flow meter the same? What is the difference and relationship between them before? Should you buy a flow meter or a flow transmitter? What kind of one to buy?

Let us discuss both flow meter and flow transmitters individually to you understand their concepts thoroughly.

Get a Quote More Flow Meters

What is a Flow Meter?

A flow meter is an instrument used to measure the flow of fluid in a pipeline or open channel. It measures the flow of fluids, liquids, or gases through a closed transmission system.

Flow meters are divided into differential pressure flow meters, rotor flow meters, throttling flow meters, slit flow meters, volumetric flow meters, electromagnetic flow meters, and ultrasonic flow meters. Classified by medium: liquid flow meter and gas flow meter.

Extended reading: Ultrasonic Flow Meters Types & Technical Guide

These different flow meters have different functional principles. For example, an orifice flowmeter calculates the fluid flow at the entrance cross-section of a narrow, restricted opening (called an orifice) and the exit cross-section of the orifice. On the other hand, a rotameter-type flow meter can measure the volume flow inside multiple tubes placed in different areas of the transfer tube.

The above is a general introduction to the flowmeter. simply put. We can think that the flow meter is composed of two parts: the sensor and the signal processor. This structure can be installed separately or as a whole.
So, the signal processing part here is the Flow Transmitter we are going to talk about next.

Extended reading: How does a rotameter work

What is a Flow Transmitter?

The flow transmitter is an important part of the flowmeter. It is a flow meter with an integrated circuit as its operating system. In the flow transmitter, the flow measurement activity is executed by the electronic circuit after receiving the command from the operator. Since flow transmitters have electronic circuits, these devices can be used to control and monitor fluid flow.

Read more about: Flow Meters With GPM Units

For example, the following picture group is the flow transmitter of our common electromagnetic flowmeter.

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Working Principle of Flow Transmitters

A transmitter (transmitter) is a converter that converts the output signal of the sensor into a signal that can be recognized by the controller. It can also convert the non-electricity input from the sensor into an electrical signal and amplify the signal source for remote measurement and control.

There are many types of transmitters. The transmitters used in industrial control instruments mainly include temperature transmitters, pressure transmitters, flow transmitters, current transmitters, voltage transmitters, and so on. Among various types of instruments, transmitters have the most extensive and common applications.

Therefore, the flow transmitter converts the flow signal collected from the flow sensor into an electrical signal. The various electrical signals that have been converted are used to facilitate the reception and transmission of other instruments or control devices. Through the electronic circuit again. Unify the electrical signals from the sensors. Converted to standard 4-20MA.

For example:
The mass flow meter directly measures the mass value. The flow transmitter displays the volume value. This is the biggest difference! The output of the flow transmitter is 4~20MA, and the pressure can be directly displayed by connecting to the secondary meter.

Read more about What is a Flow Transmitter? on Instrumentation Forum.

Extended reading: rotameter applications

Differences between the Flow Meter and Flow Transmitter

The following are some important differences between flow transmitters and flow meters.

Extended Reading: Magnetic Battery Operated Flow Meter

Flow transmitter types

In fact, there is no strict classification of flow transmitters. The flow transmitter can be configured according to the customer’s functional requirements.
For example, customers need a digital display, 4-20mA output, integrated.
Or, the customer needs battery power. Digital display. No signal output.

Extended reading: Gas Rotameter Tips

Extended Reading: What Is Metal Tube Flow Meter? Rotameter Manufacturer

Flow transmitter calculation

The calibration methods and calibration requirements of flow transmitters with different functions are different. It is recommended that you check with the manufacturer before calibrating the flow transmitter. For example, the flow transmitter supplied by Sino-Inst has a key calibration function. Simple and easy to operate.

For another example, there are two calibration methods for common electromagnetic flowmeters. You may be reading: Magnetic flow meter calibration

Extended reading: Make Ultrasonic Open Channel Flow Meter Work for You

Applications of Flow Transmitters

Flow transmitters are commonly used in various industries, including but not limited to:

• Food & Beverage
• Industrial production process
• Environmental protection project: Water and wastewater
• Pulp & paper
• Pharmaceutical
• Biotechnology
• Oil & Gas
• Energy metering
• Metals and Mining
• Marine
• Power & Utilities
• Transportation
• Chemical
• Textile
• Building Automation
• Micro Electronics
• Biotechnology
• Marine meteorology, rivers and lakes

Extended reading: Food grade flow meters for Food & Beverage industry

Extended reading: High Pressure Rotameter for Liquids/gas-Upto 25 Mpa

Related blogs

Sino-Inst offers over 50 Flow Transmitters, with the Best Price.

A wide variety of Flow Transmitters options are available to you, such as free samples, paid samples.

About 13% of these are magnetic flow meters, 14% are Insertion Magnetic Flow Meter, 25% are Venturi flow meters, 13% are ultrasonic flow meters, and others are Liquid Turbine Flow Meters.

Sino-Inst is a Flow Transmitter supplier, located in China. Flow Transmitter s products are most popular in North America, Mid East, and Eastern Europe. The United States, and India, which export 99%, 1%, and 1% of Flow transmitters respectively.

Request a Quote

KimGuo11

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects.

Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.

drurylandetheatre.com