Q: What are the types of flow meters?

Flow Metering Principles Differential Pressure Flowmeters Velocity Flowmeters Positive Displacement Flowmeters Mass Flowmeters For Open Channel Flowmeters – weirs, flumes, submerged orifices, current meters, acoustic flow meters and more For different working principle, We offer different types of flow meters, like: Differential Pressure Flow Meters Orifice Plate Venturi Tube Flow Nozzles The Sonic Nozzle – Critical (Choked) Flow Nozzle Calorimetric Flowmeter Ultrasonic Doppler Flowmeter Positive Displacement Flowmeter Variable Area Flowmeter or Rotameter Velocity Flowmeters Pitot Tubes Electromagnetic Flowmeter Turbine Flowmeter Vortex Flow Meter Thermal Flowmeter Coriolis Flowmeter Mass Flowmeters Open Channel Flowmeters

Question 1

Velocity flowmeter

Accepted Answer

Velocity gas flow meters generally consist of a flow sensor and a display.

For occasions where temperature and pressure change, a pressure gauge (sensor or transmitter), a thermometer (sensor or transmitter), a flow totalizer (temperature and pressure compensation) or a flow computer (temperature, pressure and compression factor compensation) are required.

For occasions with higher accuracy requirements (such as trade natural gas), an online chromatograph is also configured to continuously analyze the components or physical properties of the mixed gas to calculate the compression factor, density, calorific value, etc.

The main industrial applications are:

① Turbine flowmeter:
When the fluid flows through the turbine flow sensor, the turbine is forced to rotate under the action of the fluid thrust. Its rotational speed is proportional to the average flow velocity of the pipeline. The rotation of the turbine periodically changes the reluctance value of the magnetoelectric converter. The magnetic flux in the detection coil follows Periodic changes occur, generating periodic electrical pulse signals. In a certain flow (Reynolds number) range, the electrical pulse signal is proportional to the volume flow of the fluid flowing through the turbine flow sensor.

②Vortex flowmeter:
A bluff vortex generator is placed in the fluid. The fluid is alternately separated on both sides of the vortex generator to release two regular rows of alternating vortex streets. In a certain flow (Reynolds number) range, the separation frequency of the vortex is proportional to the volume flow of the fluid flowing through the vortex flow sensor.

③ Precession turbine flowmeter:
When the fluid passes through the spinner composed of helical guide vanes, the fluid is forced to rotate strongly around the centerline to form a vortex turbine. The center of the vortex precesses along a conical spiral when passing through the enlarged tube. In a certain flow rate (Reynolds number) range, the precession frequency of the vortex flow is proportional to the volume flow of the fluid flowing through the precession vortex flow sensor.

④Time difference ultrasonic gas flowmeter:
When ultrasonic waves pass through a flowing fluid, within the same propagation distance, their propagation velocities are different in the forward flow direction and the countercurrent direction. In a wide range of flow (Reynolds number), the time difference is proportional to the volumetric flow (average velocity) of the fluid being measured in the pipe.

Question 2

Positive displacement flowmeter

Accepted Answer

The gas volumetric flowmeter is a mechanical instrument. It is generally composed of a measuring body and a totalizer. For occasions where temperature and pressure change, a pressure gauge (sensor or transmitter), a thermometer (sensor or transmitter), a flow rate Totalizer (temperature and pressure compensation) or flow computer (temperature and pressure and compression factor compensation).

Inside the positive displacement flowmeter, there is a fixed large space and a set of rotating bodies that divide the space into several small spaces of known volume. Such as waist wheel, membrane, drum, scraper, oval gear, piston , screw, etc.

The rotating body rotates continuously under the action of the fluid pressure difference, and continuously discharges the fluid from a small space of known volume.

According to the number of rotations of the rotating body in a certain period of time, the volume of fluid flowing through can be obtained.

In the standard state, the volume flow calculation formula of the positive displacement flowmeter is the same as that of the velocity flowmeter.

Question 3

Differential pressure flowmeter

Accepted Answer

Differential pressure flowmeter is based on Bernoulli equation and fluid continuity equation. According to the throttling principle. When the fluid flows through the throttling part (such as standard orifice, standard nozzle, long diameter nozzle, classic venturi nozzle, venturi Sharp nozzle, etc.), a pressure difference is generated before and after it. This differential pressure value is proportional to the square of the flow.

Among the gas flowmeters, the standard orifice plate throttling device differential pressure flowmeter is the most widely used because of its simple structure, low manufacturing cost, most complete research and standardization.

Extended reading: What is an air pressure transducer?

Question 4

Gas Mass Flow Meter

Accepted Answer

Thermal Mass Flow Meter can directly measure the mass flow of various gases. Unaffected by changes in viscosity, density, temperature, or pressure.

Thermal Mass Flow Meter is a true mass flow meter. No temperature and pressure compensation is required. Thermal gas mass flow meters are designed based on the principle of thermal diffusion. Including natural gas, coal gas, liquefied gas, flare gas, argon, carbon dioxide and other mixed gas flow measurement.

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Question 5

What are the types of flow meters?

Accepted Answer

Flow Metering Principles

Differential Pressure Flowmeters
Velocity Flowmeters
Positive Displacement Flowmeters
Mass Flowmeters
For Open Channel Flowmeters – weirs, flumes, submerged orifices, current meters, acoustic flow meters and more

For different working principle, We offer different types of flow meters, like:

Differential Pressure Flow Meters
Orifice Plate
Venturi Tube
Flow Nozzles
The Sonic Nozzle – Critical (Choked) Flow Nozzle
Calorimetric Flowmeter
Ultrasonic Doppler Flowmeter
Positive Displacement Flowmeter
Variable Area Flowmeter or Rotameter
Velocity Flowmeters
Pitot Tubes
Electromagnetic Flowmeter
Turbine Flowmeter
Vortex Flow Meter
Thermal Flowmeter
Coriolis Flowmeter
Mass Flowmeters
Open Channel Flowmeters

Question 6

How do you measure gas flow rate?

Accepted Answer

The gas velocity in the pipeline is the basis for calculating the gas flow. The way to measure the gas flow rate is direct measurement or conversion through pressure measurement.

Enterprises usually use Pitot tubes (or dynamic pressure velocimetry tubes) to measure the dynamic pressure of the fluid in the pipeline first, and then calculate the flow velocity and average flow velocity at this point (the average flow velocity should be used to find the gas flow).

Because the velocity measuring tube is used to measure the velocity of the pipeline, it is only the local velocity of a certain point on the pipeline section. The flow velocity at each point on the pipeline is not the same. It is necessary to measure the flow velocity at multiple points on this section. Find the average dynamic pressure to calculate the average flow velocity.

Question 7

How does a gas flow meter work?

Accepted Answer

There are many types of gas flow meters. Such as common thermal mass flowmeters, vortex flowmeters, differential pressure flowmeters, etc. Different kinds of gas flow meters are based on different working principles.

The working principle of gas flowmeter, the common types are as follows:

Thermal gas mass flowmeter: designed based on the principle of thermal diffusion, the instrument uses the constant temperature difference method to accurately measure the gas. The sensor section consists of two reference grade platinum resistance temperature sensors, suitable for the measurement of all gas flow meters (except acetylene)
Precession vortex flowmeter: adopts the latest micro-processing technology. It has the advantages of strong function, wide flow range, operation and maintenance verification, convenient installation and use, etc. It is widely used in various gases such as petroleum, chemical industry, electric power, metallurgy, coal, etc. Measurement of liquids.
Turbine flowmeter: a speed meter. It has high precision, good repeatability, simple structure, high pressure resistance, wide measurement range, small size, light weight, small pressure loss, long life, simple operation, convenient maintenance, etc. Advantages. It is used to measure the volume flow and accumulation of low viscosity, non-corrosive, clean liquids in closed pipelines. It can be widely used in petroleum, chemical, metallurgy, organic liquid, inorganic liquid, liquefied gas, city gas pipeline network, pharmaceutical, food, papermaking and other industries.
Vortex flowmeter: The principle of Karman vortex is adopted. A triangular column-shaped vortex generator is set in the fluid, and regular vortices are alternately generated from both sides of the vortex generator. This vortex is called Karman vortex, and the vortex flowmeter is the current One of the main flow meter products in the world. It is widely used in petroleum, chemical, metallurgy, heating and other departments. Detect and measure the flow of liquid, gas and steam.
Differential pressure flowmeter: Differential pressure flowmeter is based on Bernoulli equation and fluid continuity equation. According to the throttling principle, when the fluid flows through the throttling part (such as standard orifice, standard nozzle, long Diameter nozzles, classic venturi nozzles, venturi nozzles, etc.). There is a pressure difference before and after it, and this differential pressure value is proportional to the square of the flow. Among the gas flowmeters, the standard orifice plate throttling device differential pressure flowmeter has a simple structure and low manufacturing cost. It has been standardized and has been widely used.

Question 8

What is a digital mass flow meter?

Accepted Answer

Mass flow meter directly measures the mass flow of the medium passing through the flow meter. It can also measure the density, temperature and viscosity of the medium

Mass flow meter is a flow measuring instrument that measures the mass flow in the pipeline. The volume of a fluid is a function of fluid temperature and pressure and is a dependent variable. The quality of a fluid is a quantity that does not change with time, space temperature, and pressure.

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