If you’re working in the water or wastewater treatment industry, odds are you’re going to need a submersible level sensor. Not only are these sensors extremely accurate and capable of taking continuous level readings, but they’re functional in almost any size tank or vessel, offing a distinct advantage over many sides or otherwise mounted fluid switches.
How They Work
But how do submersible level sensors work? Submersible level transmitters consist of a sensor attached to a long cable, which is then lowered to the bottom of the liquid vessel. The sensor operates by measuring the hydrostatic pressure of the liquid medium. Also known as the head pressure, hydrostatic pressure is the pressure exerted by the fluid in the vessel. The level of hydrostatic pressure as measured by the sensor is determined by two things: the density of the liquid and its height. With liquid density remaining constant, changes in hydrostatic pressure necessarily reflect a difference in the liquid level.
Of course, nothing occurs in a vacuum – especially not pressure sensing. Atmospheric conditions affecting barometric pressure above the liquid line affect the hydrostatic pressure at the bottom of the vessel as well as liquid levels. Invented or non-pressurized vessel applications where atmospheric pressure is subject to change, submersible level sensors are therefore equipped with venting to compensate, maintaining the integrity of the hydrostatic pressure readings.
The compact, sophisticated nature of the sensor unit, along with the possibility of cable lengths up to 2,500 feet in special situations, makes submersible level sensors particularly versatile. Common applications include freshwater pump controls in wells and deep wells, accurate hydrometry readings for sea or surface water levels, pump control at wastewater treatment plants, and other water treatment, retention, and usage fields.
If you’re looking for a submersible liquid level sensor for any of these or other applications, consider SMD Fluid Controls’ FT60 downhole sensor. The FT60 comes in three basic configurations, with data transmitted by a 4-20 mA output signal, ideal for long-term stability. Custom options are available to meet any of your specific application requirements.