Specific Gravity in liquid level measurement refers to the ratio of the density of a substance within a tank. For fluid monitoring levels, this factor is an important one to consider as it ensures selection the of an appropriate float switch for the task.

Choosing the right float switch means accurate reads, fewer chances of an overflow scenario and a lower risk for pump malfunction or other issues. In addition to detecting liquid in a tank, these switches can be used to activate and control devices or alarms.

In many applications, they play a critical role in the continued function and for safety. Without proper selection, the float switch could fail to do its intended job and without an alarm overflow, alerts and other problems cannot be avoided.

Instead, with specific gravity considered, there might be changes to the size and material of a float switch. For example, if the substance being measured in a tank is oil, or another corrosive chemical, knowing what the SG of that fluid is (so it will not sink)  and choosing a floats switch made of materials that can withstand harsh environments (think plastic vs. stainless steel), is critical to proper operation.

In cases when floating in the substance isn’t an option, other liquid level sensor choices such as optical and ultrasonic sensors can be used as these devices don’t depend on SG.

FLOAT SWITCHAll of SMD Fluid Control’s float-based sensors like the FS12, FS10, FM10, FM20 – are top choices when considering a specific gravity parameter.

Depending on the specific application for which a float switch is selected, it’s important to understand the SG of fluid when selecting a float switch.

In the oil industry for example, where many have a SG of around .8 or more, choosing a float that won’t sink in that density is critical.

However, for medical uses, such as monitoring a saline bag level when treating a patient, the need for accuracy and the substance used changes the requirements for which type of float switch to use.


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