Several options are available to measure flow rate using flumes and weirs, and one of the most popular methods is by implementing an ultrasonic sensor. These handy devices are quite advanced, yet their application is simple enough that anyone can use one properly, provided it’s installed appropriately. Learn how to use an ultrasonic sensor, and discover what you need to know to ensure accurate flow-rate measurements.
What Is an Ultrasonic Sensor?
An ultrasonic sensor is a device designed to measure flow rate. It’s set up above the flow stream in a flume and emits a pulse of sound. This pulse is reflected off the surface of the flowing water back to the sensor. The sensor then times how long it took to receive the echo. That information is converted into a flow rate using a preprogrammed equation, the details of which vary based on the flow and flume size.
Using an ultrasonic sensor is particularly easy because you don’t have to do any calculations yourself. The computer takes care of it all for you. You do have to make sure certain conditions are met, however, if you want reliable results. The sensor has to be installed properly, and the flow traveling through the flume has to meet appropriate criticality conditions.
How to Install an Ultrasonic Sensor
Installing an ultrasonic sensor is all about getting the measurements right. Before you can know where to put it, however, you’ll need to know the maximum anticipated level and the maximum anticipated flow rate. From this information, you can determine the zero-reference elevation. Once you have that figure, it’s time to determine the ultrasonic sensor’s blanking distance.
The blanking distance of an ultrasonic sensor is its minimum sensing range. In most cases, this range will be about 12 inches, though you can find shorter and longer distances available. This range is set with each individual ultrasonic sensor, so you’ll need an adjustable mounting bracket to adjust the height to the necessary position.
Once you’ve installed your ultrasonic sensor, it’s important to keep in mind certain considerations that could affect the accuracy of your measurements. The sound waves that are sent out from the sensor expand in a conal shape, and any angles and curves in a flume will affect how they’re reflected. The conal shape will get bigger the farther it travels, so you may need to opt for a sensor with a smaller blanking distance to ensure you’re getting useful reflections.
Ultrasonic sensors are also vulnerable to certain flow conditions. If you have to deal with foam or turbulence, for example, the sound waves could be reflecting off higher parts of the flow and offering inaccurate measurements. Fortunately, ultrasonic sensors are invulnerable to other conditions such as hard water, grease and corrosive chemicals because they don’t actually touch the water.
Ultrasonic Sensor Help From Tracom
Once you understand how an ultrasonic sensor works, getting the installation right can be a bit tricky, considering all the factors involved. Fortunately, Tracom is happy to help with our selection of ultrasonic mounting brackets that are durable and adjustable. Contact us today to get your hands on a quality mounting bracket.