Tank Level Measurements
Senix ultrasonic sensors are commonly used for tank level measurement and control. They offer cost-effective, continuous level measurement and a wide range of features to handle almost any tank level management task. Unlike mechanical level indicators and many electronic level measurement technologies, ultrasonic sensors don’t have to touch the liquid to measure it so the risk of sensor fouling or liquid contamination over time is eliminated. Here are some of the most common applications for ultrasonic tank level sensors.
Chemical Level Measurement
Many common chemicals can damage level sensors. Even stainless steel sensors can be quickly corroded by some chemicals. Transducer elements and the adhesives that bond them to housings are especially susceptible to corrosive liquids and gases. Special chemically resistant polymer housings are necessary for these environments. Simple coated transducers or partially protected sensor housings may not offer enough protection. For long-term durability, look for a chemical level sensor that provides a continuous barrier between the transducer and electronics and the chemicals being measured like our ToughSonic CHEM sensors. Also make sure to verify the sensor housing material’s resistance to the chemicals you are measuring at the operating temperatures you expect to encounter.
Tank Level Display
In the most basic application, a tank level sensor may simply transmit continuous liquid level data to a process meter or to your PC running SenixVIEW software. A simple display will provide tank level in feet or meters. With more advanced displays, you can convert simple level measurements to engineering units like gallons, liters, pounds or kilograms. ToughSonic sensors, with simultaneous outputs, allow you to select digital or analog output for display while other output(s) provide control input. Display versatility is just one of the many ways that non-contact tank level sensors out perform traditional mechanical level indicators.
Tank Level Alarms
Many tank level applications require alarms to be sounded when levels get above or below a certain point. All ToughSonic and ToughSonic CHEM sensors include 2 solid state switches that can be configured to activate alarms at pre-determined levels. Sensor switch outputs are independent of other outputs so, for example, you can maintain a continuous tank level display and alarm settings using the same level sensor.
Tank Level Control
Liquid level data is commonly transmitted to control devices such as Programmable Logic Controllers (PLCs), Remote Terminal Units (RTUs) or other computers as part of more complex process control systems. To meet the full range of system requirements, ToughSonic liquid level sensors can send measurement and control data using industry-standard serial digital, analog or switch outputs — or all three simultaneously. For example, a ToughSonic or ToughSonic CHEM sensor might provide serial data to a digital display, use switches to activate high and low level alarms and send 4-20 mA analog output to a PLC that manages the pumps or valves controlling tank level.
In simple tank control applications, you don’t even need a PLC. Simply connect the two ToughSonic solid state switches to a pump and/or valve using relays and a ToughSonic sensor will manage tank level for you. SenixVIEW software includes built-in hysteresis and time delay capabilities that allow precise control over liquid level measurement parameters.
Advanced Tank Level Measurements
Tank level measurements are sometimes complicated by conditions in the tank. Structural obstacles such as supports or mixing equipment might be in the sensor measurement path. Similarly, spray or foam can obscure the air-to-liquid interface that ultrasonic sensors detect. These applications require more advanced sensor capabilities.
One approach is to use a stilling tube. A stilling tube is a simple vented pipe that extends from the top of the tank to just short of the bottom. The sensor is placed at the top and the liquid level inside the tube follows the liquid level of the tank. The stilling tube protects the interior liquid from disturbances and provides a clear unobstructed path for the ultrasonic sound waves to follow. And since the liquid flows into the tube from the bottom where the liquid column exerts pressure, foaming is supressed.
Another approach to complicated tank level measuring environments is to use built-in sensor logic to process or filter measurements. You can use SenixVIEW to configure your ToughSonic sensor to reject certain measurements, average a series of measurement or limit the rate at which output values change. A running average of readings will smooth peaks and valleys and provide a consistent liquid level measurement. You can use the input filters in SenixVIEW to accept only maximum or minimum measurements or to negate the effect of waves or unintended objects in the measurement path. Read more about data filtering with SenixVIEW.
Senix Tank Level Experience
Senix manufactures the most versatile and rugged ultrasonic sensors in the world. We’ve guided thousands of customers through successful tank level installations and we can help you. Please contact us to see how. We’re here to help.