Measuring liquid levels in a closed-tank industrial application can pose a number of challenges. This can be an especially critical issue in industries like chemical processing, potable water storage, electroplating, oil and gas industries, and more.
Depending on the specifics of your application, including the liquid medium being measured, whether point-level or continuous level measurement is required, and available mounting positions, different liquid level sensors might provide an ideal solution. Let’s look at some of these different variables, and determine which liquid level sensors from SMD Fluid Controls are best suited to accommodate them.
The Liquid Medium
Chemical compatibility is one of the most important factors to consider when deciding on a liquid level sensor for closed tank or any other applications. There are countless possible liquid media to consider, and while we can’t go through all of them we can offer some representative examples. (Click here for a more comprehensive PDF file)
- Corrosive Chemicals – For applications involving corrosive chemicals like ammonia, acetone, nitric acid, and plating solutions, stainless steel is an excellent choice. This is not always the case, however. For example steel is not a good choice for sulfuric acid – ceramic would be a better choice.
- Petroleum and Related Oils – For petroleum oils, lubricants, and even gasoline, Buna-N or nitrile rubber is a good option. Stainless steel can also be a good choice, especially in high-temperature applications.
- Water – Most materials are acceptable for fresh water, although some, like polyethylene, should be avoided. In the case of salt water stainless steel is a better choice. Chlorinated water is a good job for ceramic or kynar.
Point Level vs. Continuous Level Measurement
Point level sensing is for when you need a sensor to determine when liquid levels are below or at or above a given point. Low level alarms or emergency turn-offs are good examples. Continuous level measurement is used to detect changes in liquid levels in real time.
Traditional float switches, either horizontally or vertically mounted, are typically ideal for point-level measurement. Side-mounted optical level sensors can also be useful for these applications.
For continuous level measurement, submersible pressure level sensors and ultrasonic level sensors are ideal.
Mounting Requirements
Depending on the size and location of your closed tank, different mounting locations might be necessary. For point level sensing where there is no access to the top or bottom of the tank, a horizontal float switch or optical level sensor would be ideal. For continuous level sensing, a top-mounted ultrasonic sensor is ideal. If top mounting is not an option, then a submersible pressure level sensor mounted to the side could be a possible solution.