Main types of flowmeters
1. VA flowmeters (variable area flowmeters or rotameters)
How it works
A float moves in a conical tube depending on the flow. The position of the float directly indicates the flow rate.
Advantages
- Robust and simple
- No power supply needed
- Clear visual readout
- Cost-efficient
Disadvantages
- Less accurate than mass flow meters
- Sensitive to contamination and orientation
- Only suitable for low to medium flows
2. Mass flow meters (for gases)
Mass flow meters measure the mass flow of gas. They are independent of pressure and temperature and offer the highest accuracy for gas measurements. Within this category there are three main principles.
MEMS sensors
These micro sensors are integrated on a chip. They offer a fast response and compact dimensions, and are ideal for OEM and instrumentation applications.
Differential pressure mass flow
This method measures a pressure difference across a restriction combined with temperature measurement. This type is robust, suitable for higher flows and applicable at higher pressures.
Capillary thermal mass flow
A thin capillary tube is heated. The heat transfer caused by the flow is converted into a very accurate mass flow value. This delivers the highest accuracy, especially at low flows and in high-purity applications.
Advantages of mass flow meters
- Very high accuracy
- Independent of pressure and temperature
- Highly reproducible
- Suitable for high-purity and corrosive gases
Disadvantages
- Always requires power supply and electronics
- Not suitable for dirt or particles without filtering
- Capillary types are more sensitive to contamination
3. Liquid Flowmeters
Liquid flowmeters are used for water, chemicals, solvents and other liquids. Technologies such as turbine, magnetic, ultrasonic, Coriolis or thermal are chosen based on viscosity, conductivity and accuracy requirements.
Advantages
- Suitable for a wide variety of liquids
- High accuracy
- Widely applicable in industry and process installations
Disadvantages
- Medium-specific choice
- Sometimes more complex installation
4. Piston flowmeters
Piston flowmeters are mechanical meters that are highly suitable for measuring liquids, even at high pressures or varying viscosities.
Focus: MAO Piston Flow Meter (Chemtec) The MAO Piston Flow Meter from Chemtec is a robust solution for critical liquid measurements. It works with a magnetic piston that is displaced by the liquid flow.
- Features: Very reliable in harsh industrial environments.
- Advantages: Can handle viscous liquids and is insensitive to turbulence in the line.
- Application: Ideal for lubrication systems, chemical injection and process monitoring where direct mechanical actuation (such as a switch) is required.
Where are flowmeters used
Industry
- Process installations such as chemicals, petrochemicals and pharmaceuticals
- Gas distribution and air management
- Pump and dosing systems
- Water treatment and cooling circuits
Laboratories and R&D
- Analytical instruments
- Test and calibration setups
- Research with low and high flows
High-purity and specialty gas
- Semiconductor processes
- Corrosive or reactive gases
- Gas conditioning and instrumentation lines
OEM and machine building
- Embedded flow sensing
- Equipment with internal flow control
- Compact modular systems
