Everything you need to know about storage tank level measurement
Containers for storing gas and liquids, called storage tanks, show up in many industries. They come in different shapes, you can install them underground, and some need to follow certain regulations.
Most storage tanks are vertical or horizontal cylinders. Some have flat bottoms, but many have conical, sloped, or dished bottoms. And depending on the industry and application, the roof may be fixed or floating.
They may store liquids or gases for short or long terms and possibly need to heat or cool the product within. You can find storage tanks in various parts of an application, holding raw materials for the first steps or for additions further in the process.
You’ll also sometimes see tank farms, where you have multiple tanks simply holding products for shipping or other non-process steps.
Storage tank level measurement
The level measurement you need will depend on the type of tank and product you have. For instance, a conical tank for a chemical has different demands than one with a flat bottom that stores water.
However, for most storage tanks, you need level measurement at least. Precise measurement requires an accurate sensor, but the right sensor will depend again on the tank and product. For instance, you can pick a non-contact sensor, like a radar level transmitter.
Even if you opted to focus only on radar level transmitters, you still get a long list of possibilities, from frequency to vendor to output and other points. However, you can also look into ultrasonic level transmitters, differential pressure transmitters, and more.
You may want to consider point level detection for your tank as well. Point level monitoring applied near the top of the tank can prevent overfill if your level transmitter malfunctions for some reason. And a level point switch near the bottom of the tank prevents pumps from running dry and incurring damage.
And what about pressure measurement? Certain products can create vapor or gas, so pressure measurement can alert you to impending vacuum or explosion so you can shut down the process and change the condition.
To automate this step, you can add a pressure safety valve (PSV). It can release pressure in the tank to the atmosphere if the transmitter or some other part fails. You can also use relief valves (RV), low-pressure safety valves (LPSV), vacuum-pressure safety valves (VPSV), and such to do the same job.
Water storage tanks
Water storage tanks range in size and use from a small rain barrel to a multi-ton tank in a water treatment plant. Water tanks usually have simpler requirements than most other products, but you still need good instrumentation to keep your plant safe and your processes running.
Level measurement in a water storage tank
You get a broad list of sensors to measure level in this type of application. Each has pros and cons, but most will do the job adequately.
Ultrasonic level transmitters provide fairly simple setup and use. As a non-contact solution, you won’t have to worry about rust or other types of interference. However, low-cost radars on the market often offer more features for a similar price. So if you’re considering an ultrasonic, you should check out radar as well.
You may want to look at hydrostatic pressure measurement, too. Although this device maintains contact with the product, the price may make it a tempting choice.
Level detection in a water storage tank
As I mentioned above, simple level monitoring can help you avoid overfill or running your pump dry. Here again, we have a range of level detection sensors to study.
If you want an easy solution, a float level switch costs less than other options, but may not last as long as you want. A capacitance level switch offers a straightforward installation and a good lifetime for a little more money.
Solutions for water storage tanks
Diesel storage tanks
You’ll find these tanks in the mining industry, on municipal generators, in storage farms, and many more places. Diesel brings more challenges than water because the vapor from diesel can explode. To mitigate this risk, your measuring devices have to follow specific requirements, such as intrinsic safety or explosion-proofing.
Level measurement in diesel storage tanks
In an application that doesn’t need high accuracy, a level transmitter and a few level switches should monitor the tank sufficiently. However, if you need high accuracy in large tanks, then you’ll want to apply a solution with more technology.
For instance, to measure level in a municipal fuel storage tank, you can use a float level switch to detect the high and low level in the tank. While this choice falls on the low end of cost and doesn’t need much to install, it requires more maintenance, and the float will often get stuck.
For constant level measurement, better accuracy, and reliability, you might look at a guided wave radar. Guided radar technology also has a straightforward setup, and some models offer Bluetooth as well. Furthermore, some have the intrinsic safety features needed for fuel storage tanks in industrial applications.
Best of all, some vendors allow remote monitoring through Ethernet, wireless, or GSM communication, with a platform to show all your level measurement data in one place.
You can find more alternatives, such as hydrostatic transmitters, in the list at the end of this topic.
Level detection in the diesel storage tank
To protect your tank at its low and high levels, you can use level switches that have on/off controls instead of or along with your level transmitter. Regardless of the control option, you can use a float level switch or better yet, a vibration fork, a reliable, maintenance-free device that gives you precise measurement.
Solutions for diesel storage tanks
When you need high accuracy, custody transfer, overfill prevention, or inventory control, then you need to apply a tank gauging solution. This system uses a precise radar level transmitter or servo to monitor level, a multi-temperature sensor to measure temperature throughout the tank, and in some cases a pressure transmitter to enable density, mass, and vapor pressure measurement.
The system sends all this data to the level management software or to the control system using protocols such as Modbus and wireless. The complexity of it deserves its own article, but we included it here to give you the option of doing your own research on it.
Solutions for diesel storage tanks
- Radar level sensor
- Temperature transmitter
- Differential pressure transmitter
- Level switch
Cement storage tanks
When we talk about storage tanks in the cement-making process, we have two crucial parts of the process that need good measurement, the coal and the cement itself.
- Coal: To make cement, you must regularly send coal to the production line. In case of an event, the operator needs a way to stop the process, so the level solution should constantly provide reliable data.
- Cement: Before it becomes sidewalks and whatnot, cement exists basically as dust. This dust goes into tanks for storage, so you need both accuracy and a way to manage build-up.
Both of these tank types can use radar level transmitters, level switches, or 3D level transmitters. Some companies will suggest guided radar as the best solution and others the free-space radar, but the best will depend on your application.
Either will work together with level switches for extra protection. And if you don’t need constant measurement, then you can stick to the switches for just level monitoring.
The 3D solution brings many more possibilities, but of course it costs more than radar level transmitter too. You have to study your process requirements and budget to decide which will give you the most bang for your buck.
Solutions for cement storage tanks
Food storage tanks
Food storage comes with a variety of needs depending on the product, so let’s look at just two examples where we have level detection and/or measurement.
- Sugar: Yes, sugar sits in giant tanks before landing in your soda or coffee cup. Build-up issues can occur in these tanks, so your solution has to compensate for that to measure the volume accurately.
- Malt: And the malt in your beer sits in tanks too. Malt, however, has both build-up and dust. That means you need a solution for both that still delivers accuracy.
Like other tanks, you can use radar level transmitters (the most common pick), level switches, or 3D level transmitters.
Solutions for food storage tanks
The product in a storage tank will dictate the complexity of your solutions. In general, it helps to have good and reliable level measurement to protect your product, your workers, and your plant. Visaya has a curated selection of these devices in our online shop for you to research.
You can choose one yourself, using the information provided on each page, or our engineering team can help you find the right device for your application. Take a look and feel free to contact us with any questions!
To know more about such products, you get in touch with our engineers!
Free space radar level sensor for water, wastewater, and other liquids in all industries