3 Highly Accurate And Reliable Ways To Measure Fluid Level
In our overview of fluid level measurements, we looked at devices ranging from the simplest to the more advanced, and the different advantages and limitation of these. This article outlines three of the most cost-effective and reliable fluid level measurement devices that allow greater efficiencies all round, namely ultrasonic, radar and capacitive.
1. Ultrasonic level devices
With ultrasonic level measurement, a sensor emits electronic pulses in the direction of the surface, which then transmits them back. The time that the ultrasound pulse takes from emission to reception at surface level is proportionate to the fluid level in the tank.
This simplicity makes them ideal for standard applications, from liquids to solids. They're also easy to install on empty or full storage tanks and can be set up in minutes. Probably the biggest advantage is that they are no-contact and have built in temperature compensation, requiring little to no maintenance. Despite alterations in chemical composition, ultrasonic level devices offer precise readings. Level measurement is thus not affected the type of liquid, temperature (although its construction materials limit temperatures to around 70°C), process pressure (3 bar usually depending on materials), or variability in density or viscosity.
Ultrasonic sensors are suitable for liquids or dry products. However, as the speed of sound can vary depending on any gas mixtures present, it is important to know if there are any gases present in the tank before using ultrasonic level measurement technology.
Radar transmitters or sensors (also known as through-air or open-air radars) send out a radar (microwave) signal that bounces off the surface before returning to the sensor. The sensor measures the time between the transmitted and received signal (total round trip time) and an on-board microprocessor calculates distance to liquid level. The key element of radar transmitters is the dielectric contact of liquid - the reflected energy at microwave (radar) frequencies depends on the fluid's dielectric constant.
Guided wave radar (GWR) transmitters are even more accurate
as they have a focused energy path. A rigid probe or flexible
cable guides the microwave signal from the top of the tank to
the liquid level and back to the sensor.
A capacitive liquid level sensor is a device used to measure
the height of a liquid and convert it to an electrical signal
to control or monitor the liquid level. They usually have a
single probe immersed inside the tank which acts as an electrode.
This probe interacts with an electrode usually placed in the
wall of the tank opposite, and the two connect to form a capacitor.
It's important to understand the uses of different level measurement
systems as well as the limitations of each before choosing a
liquid level sensor. For information on what level measurement
sensor we recommend for your specific requirements, call our
toll-free number 1-800-367-4180. We have experts on hand to
help you choose, install, and maintain a variety of equipment.
And to answer questions about things you've previously tried