The pressure at the bottom of the tank or body of liquid is related to the height of the liquid. This level pressure is called hydrostatic pressure or head pressure. Typical units of measure for hydrostatic pressure are inches, feet, or meters of water column.

27.679 inches of WC is the approximate equivalent of 1 PSI at 100°F. The volume of water or shape of the tank or vessel will not affect the hydrostatic head pressure; it is the height that affects the pressure. Whether 27.679 inches deep in the middle of a large body of water or a small bucket of water the head pressure is the same. Modern PLC's and HMI's can calulate the liquid level of a tank by entering the geometry of the tank and the specific gravity of the liquid.

Water density at 100°F (37.8°C) = 60.00 pounds per cubic foot. As you can see in this example the pressure exerted by a column of water is dependent only upon the height of the water column and is independent of the affected volume.

WH311   Submersible Pressure Transducer  offered in pressure ranges starting at 1 PSI. Available with voltage and 4-20mA output signals, these submersible pressure transducers are an accurate and cost effective solution for monitoring liquids such as: water, diesel fuel, oil, heating oil, and more. Each sensor is Applying the information outlined above is simple.WH311-FL will rest at the bottom of the tank with the density of the liquid and level providing the change in output signal.