Liquid level sensing is important in many industries and applications. From food and beverage to medical, industrial and even automotive. These sensors help predict failures, send early warnings and prevent catastrophes.

In this blog we’ll take a closer look at switches, mainly 3: Ultrasonic level switches, reed switches and optical level switches and why you should be choosing one over the other.

How Does a Reed Switch Work?

To understand how a reed switch works, first you need to know what it is. This is an electromagnetic switch that contains 2 identical reeds made of magnetized materials and placed inside of a glass capsule filled with unreactive gas. These are used in float switches and once there is a magnetic force to draw the 2 reeds inside the capsule together, the switch is operated.

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Optical Switches & Liquid Level Sensing

Optical level sensors are made of two parts: a transparent prism tip and an infrared LED with a light transistor. It is typically used to measure liquids and works by measuring the amount of returned light- which lessens as it becomes more immersed.

Ultrasonic level sensors work by using sound to measure liquid or solid media. These sensors emit a high-frequency pulse outside of human hearing range and then measure how long before the sound is returned.

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Choosing Between Reed, Optical and Ultrasonic Switches

If low cost tops your list of requirements, then reed switches may be the best option. They can be used in various outputs and are best suited for tank level applications or where contamination is a concern such as harsh environments.

In cases where very small amounts of liquid need to be measured, you may want to go with optical liquid level sensors. These switches have no moving parts but are also the most precise when it comes to measurement. In applications where leak detection or point level sensing is needed, these would offer the best option.

Ultrasonic level sensors are the most reliable option available to measure things like bulk solids or highly viscous liquids. If your application requires remote monitoring this would likely be the best option for your needs because it can continually monitor the presence or absence of media in the environment.

Need switches? SMD Fluid Controls offers a full line of sensors and switches as well as custom solutions. Contact us today, our team would love to help you!


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