The Omron 61F-G4H AC110/120 is a conductive level controller from the 61F series, classified as a High/Low Level type. It operates on a 110/120VAC supply and is designed for chassis-mount installation in control panels, typically wired via screw terminals to electrode sensors in tanks or sumps. Six relay outputs handle the switching: SPDT (2 Form C) and SPDT (3 Form C) configurations, rated at 5A @ 220VAC. That means it can directly drive pump contactors or alarm indicators without an interposing relay for most fractional-horsepower loads. The sensitivity adjustment spans 15kOhm to 70kOhm, which sets the threshold for detecting conductive liquid presence through the electrode probe. A lower setting (15kOhm) works for high-conductivity fluids like saltwater; a higher setting (70kOhm) handles low-conductivity media like deionized water or condensate. Maximum distance from the controller to the sensor is 50m, which covers most tank-farm layouts without needing a remote amplifier.
The 15kOhm to 70kOhm sensitivity range is the key selection parameter for this class. If your process fluid has a resistivity outside that window — say, ultrapure water above 1 MOhm-cm — the controller may not reliably detect the level. For most industrial water, wastewater, and chemical solutions, this range covers the typical conductivity band. Six relay outputs give you headroom for multi-point control: fill, drain, high alarm, low alarm, and two spare contacts for annunciation or interlocking. The SPDT form C contacts allow both N.O. and N.C. wiring from the same relay, simplifying fail-safe logic.