These heavy duty top-mounted liquid level controls operate in pressurized or non-pressurized tanks and sumps with pressures to 600 psi and temperatures to 500°F. They can be ordered to operate at depths to 12 feet with a 12 foot guide rod. Adjustable in single stage and two stage operation to provide action such as operating a pump; pump and high alarm or shutdown; pump and low alarm, or high and low alarm; or high, high alarm; or low, low alarm. Alarm functions can also be used as shutdowns. Series 401 is available in mercury or snap action contact switches. Specific gravity applications from 0.5 to 1.0.