If you’re looking for a durable, sophisticated device for industrial point level sensing, an optical level sensor might be what you’re looking for. Using infrared light and no moving parts whatsoever, optical sensors are ideal in environments where more traditional float switches aren’t functional. Keep reading to learn more about how they work, and decide if they’re right for your application.

How Optical Level Sensors Work

A diagram of how optical level sensors work when submerged in liquid.Optical level sensors consist of two main parts: an infrared LED coupled with a light transistor, and a transparent prism tip in the front. The LED projects an infrared light outward; when the sensor tip is surrounded by air the light reacts by bouncing back within the tip before returning to the transistor. When the sensor is immersed in liquid, the light disperses throughout and less is returned to the transistor. The amount of returned light to the transistor affects output levels, making point level sensing possible.

Advantages and Disadvantages of Optical Level Sensors

The main advantages of optical level sensors are their compact size, their lack of moving parts, and their low cost. However, while extremely accurate for point level detection in high-stress environments, they’re less useful for continuous level measurement. In addition, optical level sensors are unsuited for applications where top mounting is necessary; when top-mounted, the accuracy optical level sensors may be adversely affected by moisture condensation.

Optical Level Sensors from SMD Fluid Controls

A labelled picture of two optical liquid level sensors from SMD Fluid Controls.If you think an optical level sensor is right for your application, consider one of these two models from SMD Fluid Controls.

The OS950 plastic optical level sensor is made from a polysulfone polymer and is well-suited for sterile applications like dialysis machines, washers, and other medical appliances.

The OS150 stainless steel model is designed for high-pressure applications where corrosion resistance is necessary, such as pressurized vessels, refrigeration units, or hydraulic applications. The maximum PSI is 2,500.

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