Vortex flowmeters are widely used in various industries for measuring the flow rate of liquids, gases, and steam. The sensor is a crucial component of a vortex flowmeter, as it is responsible for detecting the vortices generated by the flow and converting them into electrical signals for further processing. In this blog, as a vortex flowmeter supplier, I will discuss the materials commonly used for the sensor of a vortex flowmeter and their properties.
Piezoelectric Crystals
Piezoelectric crystals are one of the most commonly used materials for vortex flowmeter sensors. These crystals have the unique property of generating an electric charge when subjected to mechanical stress. In a vortex flowmeter, the vortices shed from a bluff body create a fluctuating pressure field, which causes the piezoelectric crystal to deform and generate an electrical signal proportional to the vortex frequency.
The most widely used piezoelectric crystal in vortex flowmeters is quartz. Quartz is a natural piezoelectric material with excellent stability, high sensitivity, and a wide operating temperature range. It is resistant to chemical corrosion and has a long service life, making it suitable for a variety of industrial applications. Another advantage of quartz is its high mechanical strength, which allows it to withstand high flow velocities and pressures without significant damage.
Lead zirconate titanate (PZT) is another popular piezoelectric material used in vortex flowmeter sensors. PZT is a synthetic ceramic material that can be engineered to have specific piezoelectric properties. It has a higher piezoelectric coefficient than quartz, which means it can generate a stronger electrical signal for a given mechanical stress. This makes PZT sensors more sensitive and suitable for measuring low flow rates. However, PZT is more susceptible to temperature variations and mechanical shock than quartz, and its long - term stability may be slightly lower.
Strain Gauges
Strain gauges are also used as sensors in some vortex flowmeters. A strain gauge is a device that measures the strain (deformation) of a material by changing its electrical resistance. In a vortex flowmeter, the vortices cause the bluff body or a sensing element attached to it to deform, and the strain gauge measures this deformation.
The most common material for strain gauges is a thin metal foil, typically made of constantan (an alloy of copper and nickel). Constantan has a relatively high and stable resistivity, and its resistance changes linearly with strain over a wide range of strains. This makes it suitable for accurate strain measurement. The metal foil is usually bonded to a flexible substrate, which is then attached to the sensing element of the vortex flowmeter.
Strain gauge sensors are relatively simple and cost - effective compared to piezoelectric sensors. They are also less sensitive to temperature variations and can operate in a wider temperature range. However, their sensitivity is generally lower than that of piezoelectric sensors, and they may be more affected by mechanical vibrations and noise.
Capacitive Sensors
Capacitive sensors are another option for vortex flowmeter sensors. A capacitive sensor measures changes in capacitance due to the movement or deformation of a sensing element. In a vortex flowmeter, the vortices cause a change in the distance between two conductive plates or the dielectric constant between them, which results in a change in capacitance.
The materials used for the conductive plates in capacitive sensors are usually metals such as stainless steel or aluminum. These metals are chosen for their good electrical conductivity and corrosion resistance. The dielectric material between the plates can be air, a polymer film, or a ceramic material. Polymer films, such as polyimide, are often used because they have a low dielectric constant and can provide good insulation between the plates.
Capacitive sensors have several advantages. They are highly sensitive and can detect small changes in the flow field. They also have a fast response time and can measure high - frequency vortex signals accurately. However, capacitive sensors are more sensitive to humidity and temperature changes, which can affect the capacitance value and introduce measurement errors.
Considerations in Material Selection
When selecting the material for the sensor of a vortex flowmeter, several factors need to be considered.
Chemical Compatibility
The sensor material must be compatible with the fluid being measured. For example, if the fluid is corrosive, such as acidic or alkaline solutions, the sensor material should be resistant to corrosion. Stainless steel is a common choice for sensors in corrosive environments because of its excellent corrosion resistance.
Temperature Range
The operating temperature of the application is an important factor. Some materials, like quartz, can operate at high temperatures without significant degradation of their properties. In high - temperature applications, such as Steam Flowmeter, materials that can withstand the high temperatures are essential. On the other hand, in low - temperature applications, the material should not become brittle or lose its sensing properties.
Flow Velocity and Pressure
The sensor material must be able to withstand the flow velocity and pressure of the fluid. High - velocity flows can cause mechanical stress on the sensor, and the material should have sufficient strength to avoid damage. For high - pressure applications, materials with high mechanical strength, such as quartz or some types of ceramics, are preferred.
Accuracy and Sensitivity Requirements
The required accuracy and sensitivity of the flow measurement also influence the material selection. For applications that require high accuracy and sensitivity, piezoelectric sensors may be the best choice. However, if cost is a major concern and a lower level of accuracy is acceptable, strain gauge or capacitive sensors may be more suitable.
Our Vortex Flowmeter Products
As a vortex flowmeter supplier, we offer a wide range of vortex flowmeters with different sensor materials to meet the diverse needs of our customers. Our Temperature And Pressure Compensate Flowmeter is designed to provide accurate flow measurement under varying temperature and pressure conditions. It uses high - quality piezoelectric sensors for reliable and precise measurement.
Our Lugb Vortex Flowmeter For Gas, Liquid And Steam is suitable for measuring the flow of different types of fluids, including gases, liquids, and steam. It can be equipped with either piezoelectric or strain gauge sensors, depending on the specific application requirements.
Contact Us for Purchase and Negotiation
If you are interested in our vortex flowmeters or have any questions about the sensor materials and their applications, please feel free to contact us. We have a team of experienced engineers who can provide you with professional advice and solutions. Whether you need a standard vortex flowmeter or a customized one, we are committed to meeting your needs and providing you with high - quality products and services.
References
- White, F. M. (2011). Fluid Mechanics. McGraw - Hill.
- Doebelin, E. O. (2004). Measurement Systems: Application and Design. McGraw - Hill.
- ISO 10790:2007. Industrial - process control valves - Flow capacity - Sizing equations for fluid flow under installed conditions.
