Flowmeter Manufacturers : Guide to Selecting Common Liquid Flowmeters

As a flow meter manufacturer, we have cases in industrial production, municipal water supply, energy and chemical industries, etc. Here is a summary of the flow meter purchase guide:

Accurately measuring liquid flow is crucial for ensuring production efficiency, cost control, and safety. Turbine flowmeters, electromagnetic flowmeters, ultrasonic flowmeters, and vortex flowmeters are the four most widely used flow measurement devices in the liquids sector. Each relies on a unique operating principle, resulting in differentiated performance advantages and application boundaries.

Analysis of the core characteristics of 1.4 mainstream liquid flow meters

(1) Turbine flowmeter

1.1 Usage Scenarios

Turbine flowmeters, with their high-precision measurement advantages, are widely used in clean liquid applications requiring high flow measurement accuracy. These include metering the delivery of refined oils such as light oil and diesel in the petrochemical industry, filling and metering sterile liquids such as purified water and milk in the food and beverage industry, and precisely metering the delivery of liquid medicines in the pharmaceutical industry. They are also widely used in monitoring the flow of lubricating media such as lubricating oil and hydraulic oil in industrial cooling systems, and are particularly suitable for medium- to low-viscosity, impurity-free liquids.

1.2 Advantages

High measurement accuracy : Within the rated flow range, the accuracy can usually reach ±0.2%~±1.0%. It is one of the most accurate types of liquid flow measurement currently and can meet the needs of high-precision measurement.

Fast response speed : Turbine blades are highly sensitive to flow changes and can quickly capture instantaneous fluctuations in flow, making them suitable for dynamic scenarios that require real-time monitoring of flow changes.

Compact structure and easy installation : It is relatively small in size and light in weight, requires less installation space, and has flexible installation methods. It can be connected by flange, clamp or thread to adapt to different pipeline layouts.

Small pressure loss : Under normal operating flow, the pressure loss of the fluid passing through the turbine flowmeter is relatively small and will not affect the pressure balance of the entire piping system too much.

1.3 Disadvantages

High requirements for medium cleanliness : Turbine blades are easily worn or stuck by impurities and particles in the medium, resulting in reduced measurement accuracy or even equipment damage, so strict filtering devices must be equipped.

Greatly affected by the viscosity of the medium : When measuring high-viscosity liquids, the viscosity of the liquid will reduce the speed of the turbine blades, resulting in low measurement results.

Susceptible to mechanical wear : The turbine blades and bearings are in mechanical contact, which will cause wear after long-term use. Regular maintenance and replacement are required, and the service life is relatively short.

(2) Electromagnetic flowmeter

2.1 Usage Scenarios

Electromagnetic flowmeters operate based on the principle of electromagnetic induction and are unaffected by physical parameters such as medium density, viscosity, and temperature. They are suitable for measuring conductive liquids and are widely used in municipal sewage treatment, industrial wastewater discharge measurement, chemical industry transportation monitoring of corrosive liquids such as acid and alkali solutions and salt solutions, and metallurgical industry flow measurement of liquids containing solid particles such as slurries and muds. They also perform well in the food industry for measuring viscous conductive liquids such as sauces and syrups.

2.2 Advantages

Strong adaptability to media : As long as the conductivity of the medium is ≤20US/cm, accurate measurement can be achieved regardless of changes in its viscosity and density. It can measure fluids containing particles, suspended matter, and even corrosive fluids such as mud and slurry.

Stable measurement accuracy : Within the measuring range, the accuracy can reach ±0.5%~±1.0%, and is less affected by flow changes.

No mechanical wear and long service life : There are no moving parts in the measuring tube, and measurement is achieved only by electromagnetic induction, which avoids mechanical wear and tear and reduces maintenance costs.

Minimal pressure loss : The inner wall of the measuring tube is smooth, and there is almost no pressure loss when the fluid passes through it. It is suitable for systems with strict requirements on pipeline pressure loss.

Measurable reverse flow : With bidirectional measurement capabilities, it can accurately capture the forward and reverse flow of liquids, making it suitable for scenarios where fluid reflux needs to be monitored.

2.3 Disadvantages

Unable to measure non-conductive liquids : Liquids with a conductivity of ≤20US/cm (such as gasoline, diesel, alcohol, pure water, etc.) cannot be effectively measured, which is its most core application limitation.

Affected by external electromagnetic interference : If there are strong magnetic fields or high-frequency interference sources (such as large motors and transformers) near the installation environment, the measurement accuracy will be affected and shielding measures need to be taken.

(3) Ultrasonic flowmeter

3.1 Usage Scenarios

Ultrasonic flowmeters utilize a non-contact measurement method, eliminating the need for direct contact with the medium. These meters are suitable for a variety of complex scenarios, such as monitoring flow in large-diameter pipelines in municipal water and heating systems, measuring the flow of flammable, explosive, and corrosive liquids in the petrochemical industry, and measuring sanitary liquids in the food and pharmaceutical industries. Furthermore, they offer a significant advantage in flow renovation projects involving older pipelines, as they can be installed without disconnecting the pipe.

3.2 Advantages

Non-contact measurement, highly adaptable : The sensor is installed on the outer wall of the pipe and does not need to come into contact with the medium, avoiding the problem of medium corrosion and sensor contamination. It can measure flammable, explosive, highly toxic, highly corrosive and other special liquids.

Easy installation without affecting pipeline operation : installation can be completed without cutting off the pipeline or stopping production. It is especially suitable for flow monitoring renovation of old pipelines or large-diameter pipelines that cannot be shut down.

3.3 Disadvantages

Greatly affected by pipeline conditions : scaling, corrosion, and rust on the inner wall of the pipeline will cause the ultrasonic reflection signal to weaken, affecting the measurement accuracy; some pipeline materials may affect measurement.

It is significantly affected by the characteristics of the medium : if the medium contains a large number of bubbles and suspended particles, it will cause ultrasonic scattering and increase the measurement error; the measurement accuracy of high-viscosity liquids will also decrease.

The measurement accuracy is relatively low : the accuracy of conventional ultrasonic flowmeters is ±1%~±1.5%, which is lower than that of turbine flowmeters and electromagnetic flowmeters, and it is difficult to meet the needs of high-precision measurement.

Limited environmental adaptability : In high temperature, high humidity, and strong vibration environments, the stability of the sensor will decrease, and additional protective measures need to be taken.

(4) Vortex flowmeter

4.1 Usage Scenarios

Vortex flowmeters operate based on the Karman vortex principle and are suitable for measuring clean liquids within a certain Reynolds number range. They are widely used for monitoring cooling water flow in industrial cooling systems, metering the delivery of low- to medium-viscosity liquids such as solvents and reagents in the chemical industry, and measuring the flow of liquids such as light oil and thermal oil in the energy industry. They are also widely used for monitoring the flow of chilled and hot water in air conditioning systems, and are particularly suitable for measuring medium- to high-speed liquids.

4.2 Advantages

Simple structure and high reliability : There is only one vortex generator in the measuring tube, no moving parts, low risk of mechanical failure, low maintenance cost and long service life.

Moderate pressure loss : Compared with the turbine flowmeter, the pressure loss is slightly higher, but lower than the throttling flowmeter, and has little impact on the pressure of the pipeline system.

High measuring temperature : It can measure high temperature media and can support up to 350° for high temperature media.

4.3 Disadvantages

There are certain requirements for the cleanliness of the medium : if the vortex generator is attached or stuck by impurities or particles in the medium, it will affect the stability of vortex generation and increase the measurement error. Therefore, it is not suitable for liquids containing a large amount of suspended particles.

Greatly affected by low flow : When the liquid flow rate is low, it is difficult to form a stable Karman vortex street, the measurement accuracy will be significantly reduced, or even fail to work normally, so there is a minimum flow rate requirement.

Weak anti-vibration ability : External vibrations can easily interfere with the frequency of the vortex street, leading to mismeasurement. Therefore, it needs to be installed in an environment with less vibration or equipped with a vibration compensation device.

2.4 Types of flow meter core parameter comparison and adaptability analysis

(1) Comparison of core parameters

Parameter Type	turbine flowmeter	Electromagnetic flowmeter	Ultrasonic flowmeter	Vortex flowmeter
Measurement accuracy	±0.2%~±1.0%	±0.5%~±1.0%	±1%~±1.5%	±1%~±2.5%
Dielectric conductivity requirements	No requirements	≤20us/cm	No requirements	No requirements
Medium cleanliness requirements	High (needs filtering)	Low (may contain particles)	High (particulate matter affects accuracy)	High (avoid impurities adhesion)
Pressure loss	Small	Very small	none	Small
Maintenance costs	High (requires regular blade/bearing replacement)	Low	Low	Low

(2) Scenario suitability analysis

Based on the above parameter comparison and the performance characteristics of each flow meter, the adaptability in different scenarios can be divided into three levels: "highly adaptable", "generally adaptable", and "unsuitable". The specific adaptability is as follows:

2.1 High-precision clean liquid metering scenarios (such as finished oil filling and liquid medicine delivery)

2.1.1 Highly adaptable: Turbine flowmeter. Its high accuracy of ±0.2% to ±1.0% and high repeatability can meet measurement needs, and it has excellent stability in clean, low-viscosity liquids.

2.1.2 General adaptation: The electromagnetic flowmeter needs to be liquid conductive and have an accuracy that meets the requirements. It is large in size and is ineffective for non-conductive liquids.

2.1.3 Incompatibility: Ultrasonic flowmeters have insufficient accuracy and vortex flowmeters have poor stability at low flow rates.

2.2 Corrosive/particle-containing liquid measurement scenarios (such as chemical acid and alkali solutions, sewage treatment)

2.2.1 High adaptability: Electromagnetic flowmeters are corrosion-resistant and can adapt to media containing particles.

2.2.2 General adaptation: Ultrasonic flowmeter, non-contact measurement can avoid corrosion, but the accuracy decreases when there are a lot of bubbles or particles.

2.2.3 Incompatible: Turbine flowmeters are prone to corrosion and blocking, and vortex flowmeters are prone to impurities adhering to them.

2.3 Large-diameter pipeline/old pipeline renovation scenarios (such as municipal water supply and heating systems)

2.3.1 High adaptability: Ultrasonic flowmeters. Non-contact installation does not require cutting the pipe and is suitable for large-diameter pipes; electromagnetic flowmeters can be inserted.

2.3.2 General adaptation: The electromagnetic flowmeter has high accuracy but requires pipe cutting for installation, making modification difficult.

2.3.3 Incompatible: Turbine flowmeters are used for pipes with a small diameter, and are not suitable for pipes with diameters above DN200. Vortex flowmeters are not suitable for pipes with diameters above DN300.

3. The core decision logic of flow meter selection

In practical applications, the selection of flow meters must follow the principle of "scenario priority and parameter matching". The specific decision-making steps are as follows:

3.1 Identify the media characteristics : First, determine the liquid's conductivity (whether it is conductive), cleanliness (contamination), and viscosity (high/medium/low viscosity). This is key to eliminating incompatible flowmeters. For example, non-conductive liquids should be directly excluded from electromagnetic flowmeters, while liquids containing large amounts of particles should be excluded from turbine flowmeters.

3.2 Measurement accuracy requirements : For high-precision scenarios such as trade settlement and precision filling, turbine flowmeters or electromagnetic flowmeters are preferred; for medium and low-precision scenarios such as routine monitoring and process control, vortex flowmeters or ultrasonic flowmeters can be selected.

3.3 Pipeline and environmental conditions : According to the pipeline diameter, ultrasonic flowmeters are given priority for pipelines above DN200, and turbine flowmeters and ultrasonic flowmeters are given priority for installation in a small space; environmental vibration/temperature: avoid choosing vortex flowmeters for large vibrations, and choose vortex flowmeters for high temperature environments.

4. Flow meter manufacturer recommendations

Turbine, electromagnetic, ultrasonic, and vortex flowmeters each have their own strengths and weaknesses in liquid flow applications, and there's no such thing as a "one-size-fits-all" flowmeter. Achieving accurate, stable, and efficient flow measurement requires a comprehensive assessment based on the media's characteristics, measurement requirements, pipeline environment, and cost budget.