The Model 404 Liquid Level Sensor operates in conjunction with a Model 403 Controller for bubbler-type duplex pumping systems. The 404 contains an air pressure-to-voltage transducer and requires only a small air compressor capable of 15 psi to operate the system down to approximately 35 feet. The Model 404s four outputs are designed to replace the float switch inputs to a Model 403, or to be used with a Model 448 output Relay Board. A 4-20mA signal output provides for other control applications. A 3-digit LED display continuously shows the liquid level to a tenth of a foot when the Display Control switch is in the Liquid Level position. Other settings of the switch allow setting of the liquid level trip points. LED indicators illuminate as the levels are exceeded. A test control allows the trip settings to be checked without actually raising or lower the liquid level.. Specifications: Voltage Range: 20-28VAC