Bridging the Gap: From Level Detection to Intelligent Control—Webinar

Kelvin:
This is Kelvin with ControlByWeb, and I’m here with Shaw Merrill from Automation Products Group. Today we’re going to talk about level measurement and control—from the instrumentation side, the sensor side, all the way to the controller and what you do with that signal.

Specifically, we’re focusing on ultrasonic level sensors. Shaw is our expert—he’s with APG, Automation Products Group. They’ve been manufacturing ultrasonic level sensors and other sensor technologies since the ’80s.

Shaw:
Since the ’80s—yeah, a little over 30 years.

Kelvin:
It’s been a long time. Shaw’s been there almost the entire time—he’s the guy. APG has been manufacturing ultrasonic level sensors and other technologies for over 30 years here in the USA.

Shaw:
Built to order. We do have some off-the-shelf options, but most of our sensors are custom-ordered to match what the customer wants.

Kelvin:
Right—matching the sensor technology to the application. Today we’re going to focus on ultrasonic sensing, and then we’ll talk about how ControlByWeb controllers take that signal and turn it into conditional logic, remote alarms, notifications—everything you want out of a controller, especially in the modern IoT age.

So Shaw, take it away. Tell us about ultrasonic sensors.

Shaw:
Let’s start with the basics—how ultrasonics work. An ultrasonic sensor uses sound waves to measure distance or level. You can also use them for presence detection.

The sensor sends a sound wave from the face of the sensor to the surface of whatever you’re measuring. In a water tank, for example, the sound wave travels to the water surface, bounces back, and the sensor measures the time it takes to return. That time is then converted into a distance or level reading.

From there, we provide an output—either a 4–20 milliamp signal or a Modbus RS-485 output that can be used by control devices.

One major advantage of ultrasonic sensors—whether in water tanks, chemical applications, or water and wastewater—is that they’re non-contact. The sensor never touches the medium being measured, which is important for things like potable water where contamination is a concern.

Another advantage is cost. Ultrasonic sensors are relatively inexpensive compared to other level-measurement technologies. For around $400–$500, you can get a sensor that does an excellent job. Pair that with a controller and you’re under $1,000 for a full application—which is tremendous value.

Accuracy is another benefit. Ultrasonic sensors typically offer around 0.25% accuracy of the detected range. For most applications, that’s more than enough—many users only need one or two percent accuracy.

Installation is also very simple. Our ultrasonic sensors typically come with a 2-inch or 3-inch NPT thread and mount right on top of the tank. You wire it to your controller, and it’s essentially plug-and-play.

If you want to fine-tune the sensor—adjust max distance, filtering, or other parameters—you can do that too. But at a basic level, our ultrasonics are designed to be installed quickly and just work.

Kelvin:
There are a few things to keep in mind during installation, though. You need to protect that sound wave and make sure it’s not hitting anything unintended. What about beam angle?

Shaw:
Our sensors have a 9-degree beam angle. As the sound travels farther, it spreads out. That means you need to consider the tank environment—vapors, foam, or obstructions can cause false readings.

Foam and heavy vapor aren’t ideal for ultrasonics because the sound wave can bounce off those instead of the liquid surface. In those cases, you might look at radar or a submersible pressure transducer instead.

You also want smooth tank walls and proper mounting—not directly against the wall or dead center if there are internal obstructions. Placement matters.

We have installation videos, programming guides, and best practices available on our website to help users get the most accurate readings.

Kelvin:
Ultrasonics are used in a huge range of applications—especially water and wastewater, stormwater monitoring, sewer systems, and car washes.

In car washes, for example, ultrasonics are used to profile vehicles—detecting whether it’s a sedan or a pickup so the equipment can adjust accordingly.

They’re popular because they’re inexpensive, easy to install, and accurate—making them a great general-purpose level or distance sensor.

You can get them with 4–20 mA outputs, Modbus, and other options depending on what your system needs.

So Shaw, if someone remembers just three things about ultrasonic sensors, what should they be?

Shaw:
First, know your environment—vapors, foam, and tank conditions determine whether ultrasonic is the right technology.

Second, know your measurement range. Our sensors range from about 9 inches all the way up to 50 feet, with 25 feet being very common.

Third, consider your budget. If you want a reliable, budget-friendly solution, ultrasonic sensors are hard to beat.

Kelvin:
Once you have an accurate sensor, the next step is deciding what to do with that signal. That’s where controllers come in.

ControlByWeb manufactures controllers like the X404 and X412. The X404 handles Modbus RS-485 inputs, while the X412 is one of our most popular analog input devices for 4–20 mA or 0–10 V signals—and it also includes four built-in relays.

These devices are commonly paired with APG ultrasonic sensors. They’re edge controllers, meaning they process data right at the sensor level.

Our controllers support multiple protocols—Modbus TCP/IP, MQTT, and REST APIs. MQTT is especially powerful for remote sites due to encryption and low bandwidth usage. Our devices can also be accessed directly through a web browser—no special software required.

At $300–$600, these controllers function like streamlined PLCs. Pair one with an APG ultrasonic sensor and you have a complete level measurement and control system for under $1,000.

Shaw:
One big advantage is scalability. If you have multiple tanks or sensors, you can connect several to a single controller.

Kelvin:
Exactly. The X404 can monitor up to 32 Modbus sensors daisy-chained together. With APG sensors specifically, the registers auto-populate—no manual Modbus mapping required. It’s about as plug-and-play as Modbus gets.

Shaw:
That removes a huge barrier. Modbus can be intimidating, so simplifying that setup makes it much more accessible.

Kelvin:
That’s really our philosophy—powerful enough for engineers, but simple enough for operators and maintenance teams.

You can do basic pump control—turning a pump on at low level and off at high level—or add remote alerts, emails, text notifications, and data logging to the cloud or a local server.

Shaw:
So you can monitor everything from anywhere.

Kelvin:
Exactly. As long as the controller is networked, you can log in via its IP address and see live data, change logic, and control relays right from your browser.

Shaw:
When you pair APG ultrasonic sensors with ControlByWeb controllers, you really have everything you need—measurement, control, monitoring, and reporting.

Kelvin:
And with both companies designing and manufacturing in the U.S., you get strong support and reliable products.

Shaw:
If you want to learn more about APG ultrasonic sensors, visit apgsensors.com. You’ll find spec sheets, installation guides, and setup videos.

Kelvin:
And for ControlByWeb controllers, visit controlbyweb.com for application examples and tutorials.

Thanks again, Shaw, for joining us today.

Shaw:
Thanks for having me.

Kelvin:
And thank you all for watching. We’ll see you next time.