Liquid and solid level monitoring

Liquid and solid level measurement is not new and it is one of the most common practical use cases appearing around.

Almost all new businesses starting up in the IoT field will deploy, at some point, an ultrasonic sensor above a water tank then publish a quick post about the achievement. Don’t misunderstand. This method of measurement is one of the fastest and easiest to implement. There are plenty of ready made transmitters and sensors combinations, fast to deploy and quite inexpensive, hence their popularity.

There are, however, challenges in terms of liquid or even solid/silo level monitoring. Contaminants such as dust particles, interference from moving water surfaces, vegetation,  even interference from enclosures can present a few of problems.

Tank level and silo level monitoring

In tank monitoring using ultrasonic methods leaves the sensor exposed to condensation interference, vessel wall interference. The installation has to be quite precise since a wrong angle would allow the ultrasonic wave to reflect of the vessel itself. Condensation also causes false readings and the installation would require regular maintenance.

Some solutions to overcome this are combination measurements, weight monitoring  or even wall distortion measurement. These methods are not as known or popular due to their implementation and cost but they offer more accurate results with less maintenance.

Water monitoring – rivers, lakes

When deploying along water banks, the surrounding vegetation can be a source of false readings for ultrasonic measurements. Water engineers prefer level loggers based on pressure such as the Seametrics C2X or the InSitu Logger. Their cost is higher and the installation has to be precise but their accuracy is such that these devices are the go-to devices for water modelling. Working in partnership with the scientist, the installation and telemetry company has to also tak into account the type of sediment moved by the water. If mud gets into the measurement ports, the pressure sensors stop functioning correctly.

Depending on the type of logger, some require a second barometric sensor which would have to report atmospheric readings for pressure compensation. This is one of the most common methods used in natural resource industry operations.

Another used method is radar based. This is more often implemented over large water bodies with running water such as wider rivers. This method has a distinct advantage of not requiring any special anchoring in the ground for level monitoring as would be the case of a pressure sensor. It also reduces the rick of damage by foreign bodies such as logs and boulders carried by the current. One of the disadvantages is that the measurements are less accurate and thus not used  water level modelling.

Fuel tanks

Level monitoring doesn’t have to be just about water. Fuel tanks such as diesel are perfect applications. One of the advantages of the technology is that there is less interference from the liquid and the impact of the measured substance on the right sensor is negligible.

This application is perfectly suited for pressure sensors with the transmitter located outside the ATEX area. Weight sensors can also be used although for large vessels this would be nearly impossible to implement

Conclusion

Not one single method is the perfect one. That is known. Customers need to make sure that the IoT telemetry specialist keeps an open mind about the technology used.

SimplyCity Australia has implemented all the above solutions.

When designing a solution with the customer, our team has to understand many factors: environment, access, robustness, challenges. A long term, efficient and functional solution is the result of an extensive analysis of the customer’s needs and requirements.