Over the years, we’ve had several customers approach us about measuring their tanks on their trucks. While this unique application presents a variety of challenges, and often requires some fine tuning, you can get a reliable and accurate reading on a tank truck with the right liquid level gauge.
We’ve found that there’s not a single level measurement technology that works on all tanks on trucks. There are many variables to consider. However, one technology does seem to stand out among the rest.
This blog post will explore three measurement technologies: ultrasonic sensors, pressure sensors, and continuous float level transmitters. All three are used in measuring tanks levels, but there’s some tricks to get them working at optimal performance, and one stands out as the best product for liquid level measurement for tanks on trucks.
Ultrasonic Level Sensors
Ultrasonic sensors have been a popular choice for most liquid level measurements. They’re easy to install and they don’t come in contact with the liquid. But when it comes to liquid measurement on truck tanks, things get a little more challenging.
The main challenge is that the liquid will be moving and sloshing around inside the tank as the truck travels. This makes it difficult for the ultrasonic sensor to get a good reading. This may also cause problems if the liquid splashes on to the transducer face, especially if the liquid is a hazardous chemical.
An effective way to diminish turbulence is to use a stilling well (see “The Art of the Stilling Well”). This will usually calm the liquid inside the pipe, preventing the sensor from getting splashed and making it easier for the sensor to get a good reading.
Temperature gradients are another factor that causes concern. Being outside in the sun, tanks on trucks will often get quite hot. The temperature difference between the ultrasonic sensor and the liquid it’s measuring may fluctuate, leading to inaccuracies in the readings.
One way to combat this is to turn off the temperature compensation feature in the ultrasonic sensor to avoid overcompensation. Installing a shade over the ultrasonic sensor is another good prevention method.
Pressure Sensor Level Gauges
Pressure sensors are also susceptible to fluctuating temperatures. Some liquids will expand or contract significantly as temperatures fluctuate. Since pressure sensors rely on the specific gravity of the liquid to remain constant, they won’t notice an increase in level due to an expanding fluid.
Due to how the pressure sensor operates, there’s no way to negate this effect unless you use a temperature sensor in conjunction with the pressure sensor, and then use the raw readings to calculate a compensated reading. This usually isn’t worth the effort when other options are available.
Continuous Float Transmitters
In our experience, we’ve found this type to be the best option. Continuous float transmitters are simple to install and require no programming. These float and stem transmitters rely on the position of the float on its stem, so fluctuating temperatures aren’t as much of a worry. As long as the specific gravity doesn’t drop below the specific gravity of the float—and our floats can be swapped out to whatever best suits your application—you’ll still get an accurate reading for the liquid in the tank.
As trucks can carry hazardous chemicals in their tanks, a sensor needs to be tough if it’s coming in direct contact with the liquid. Our stems and floats are both constructed out of sturdy materials, so they aren’t worried about sitting directly inside a tank filled with hazardous chemicals.
Our continuous float transmitters also tend to handle turbulent fluids better as well. The float rises up and down with the rolling fluids as the truck moves. We recommend using a stilling well with these transmitters to ensure you get the best reading possible.
If you have any questions on using liquid level gauges for tanks on trucks, feel free to contact us. Our sales team will be happy to help you find a solution for your unique application.
