Main features and applications of commonly used liquid flow meters

Project Overview

1.Volumetric flowmeter

Volumetric flowmeter (also known as fixed displacement flowmeter), is a higher accuracy of the total amount of measurement instruments. According to its measuring element can be divided into spiral rotor (double rotor) flowmeter, scraper flowmeter, elliptical gear flowmeter, disc flowmeter, rotary piston flowmeter, liquid seal rotary cylinder flowmeter, etc., its main features are as follows.

Advantages: high measurement accuracy; can be used for high viscosity liquid measurement, suitable for clean single-phase fluids; direct-reading instrument without external energy can directly obtain the total cumulative flow; easy to install, no special requirements for the front and rear of the straight pipe section.

Disadvantages: not suitable for high and low temperature occasions; the type of medium to be measured, calibre limitations; pressure loss is large; the need for regular calibration.

Application: volumetric flowmeter with its high accuracy measurement characteristics, in the energy, petroleum, pharmaceutical, food, chemical and other fields are widely used, especially in the measurement of crude oil and other liquid media, the need for storage and transportation, handover and distribution, etc., and as a basis for financial accounting or as a taxable buyer and seller to implement the contract of the legal measurement.

2.Differential Pressure Flowmeters

Differential pressure flowmeter is one of the more widely used types of flow meters, which can be divided into orifice plate flowmeter, venturi flowmeter, homogeneous tube flowmeter and so on according to the detecting piece (primary instrument), and its main features are as follows.

Advantages: wide range of applications, can measure all single-phase fluids, part of the mixed-phase fluids; simple and solid structure, easy maintenance, long service life; detecting parts and transmitters, display instruments produced by different manufacturers, to facilitate the scale of economic production.

Disadvantages: Measurement accuracy in general; large pressure loss (orifice plate, nozzle, etc.); installation conditions require high, before and after which there must be a long enough straight pipeline.

Application: as an earlier measurement, in the closed pipe flow measurement, differential pressure flowmeter for a variety of conditions can be applied to the object, the use of this type of flowmeter accounted for about all the flowmeter dosage of 1/4 ~ 1 / 3.

3.Coriolis Mass Flow Meters

Coriolis mass flow meter in the domestic application started late, but it can directly measure the mass flow of the fluid in the pipeline, its main features are as follows.

Advantages: high measurement accuracy; wide range of measuring fluids, including liquids containing traces of gases; no requirement for installation on upstream and downstream straight pipe sections.

Disadvantages: low-density media and low-pressure gas can not be measured, the gas content of the liquid exceeds a certain limit will affect the measurement accuracy; sensitive to external vibration interference, in order to prevent the impact of pipeline vibration, most of the sensor installation and fixation requirements are higher; restricted pipe diameter, can not be used for larger diameters; measurement of the pipeline scaling or wear and tear of the inner wall will affect the accuracy of the measurement; pressure loss is greater.

Applications. Coriolis mass flowmeter is particularly suitable for the viscosity of the medium, because of its high accuracy and stability, therefore, developed countries in the chemical, pharmaceutical, petroleum, energy, food and other industrial areas have been a large number of use of this kind of flowmeter, in the transport sector is commonly used in the measurement of fluid pipeline transmission.

4.Ultrasonic flowmeter

Ultrasonic flowmeter can be roughly divided into insertion type, pipe section type, external clamping type and portable type, etc., and its main features are as follows.

Advantages: non-contact measurement, suitable for large calibre and large flow measurement; no pressure loss, no interference with the fluid; suitable for any liquid; easy installation and maintenance.

Disadvantages: when the measured fluid contains bubbles or noises, it will affect the measurement accuracy; the temperature range of the measurable fluid is limited by the temperature resistance of the ultrasonic transducer and the coupling material between the transducer and the pipeline, and the raw data of the sound transmission speed of the measured fluid at high temperatures are incomplete.

Applications. Ultrasonic flowmeter in the petroleum, chemical, metallurgy, electric power and other fields are widely used, often used in the factory discharge liquid, dirty process liquid and other flow measurement, as well as the operation area of the pipeline of the West-East gas pipeline measurement.

5.Magnetic inductive flowmeter

In the 1970s and 80s of the 20th century, there was a major technological breakthrough in electromagnetic flow, making the number of uses of this flowmeter rising, and its main features are as follows.

Advantages: suitable for measuring liquid-solid two-phase fluids containing solid particles; no pressure loss; not affected by fluid properties.

Disadvantages: Cannot measure liquids with low conductivity, such as petroleum products and organic solvents; Cannot be used to measure liquids at higher temperatures; Cannot measure gases, vapours and liquids containing more large bubbles.

Application: Electromagnetic flowmeter in the large calibre instruments are often used in water supply and drainage projects; small and medium calibre instruments are often used in high requirements or difficult to measure occasions, such as strong corrosive liquids in the chemical industry, the paper industry to measure the pulp liquid and black liquor; small calibre, small calibre is often used in the pharmaceutical industry, the food industry, the bio-chemical industry and other fields.

6.Turbine flowmeter

Turbine flowmeter products have now developed into a multi-species, multi-series mass production scale, its main features are as follows.

Advantages: high accuracy, generally ±0.25%R~±0.5%R when measuring liquid, even up to ±0.15%R; good repeatability, short-term repeatability of up to 0.05%R~0.2%R; no zero drift, strong anti-interference ability.

Disadvantages: The physical properties of the fluid have a large impact on the flow characteristics; the calibration characteristics cannot be maintained for a long period of time.

Application: Turbine flowmeter is often used to measure petroleum, organic liquids, inorganic fluids and low-temperature fluids, etc. It is used for trade settlement in the transfer and gathering stations of refined oil products, light crude oil, etc., and the first and last stations of large-scale crude oil transmission pipelines in foreign countries.

7.Vortex flowmeter

Vortex flowmeter is one kind of flowmeter, but its development is rapid, and now it has become a common category, its main characteristics are as follows.

Advantages: wide range of applications for flow measurement of liquids, gases and vapours; low pressure loss; easy installation, simple and solid structure.

Disadvantages: poor anti-interference ability; installation requirements before and after the straight section; in the pulsating flow, multi-phase flow is still lack of application experience.

Applications: Vortex flowmeters are used in a wide range of applications and are commonly used in factory water supply systems, where applications in high viscosity, low flow rate, and small diameter situations can be limited.