Non-contact liquid level sensors and transmitters mount outside or onto the bung port of a container or tank, using radio or ultrasonic technology to measure levels. Since these level sensors do not immerse in the measured substance, they're suited for corrosive liquids, wastewater, and bulk storage containers. Non-contact ultrasonic liquid level sensors emit acoustic sound waves to monitor liquid levels. Non-contact radar liquid level sensors emit electromagnetic waves to monitor liquid levels. These sensors are not affected by ambient conditions and, as a result, are suited for level sensing in high-pressure and temperature environments, agitated liquids, foams, and liquids generating fumes.