Contact liquid level sensors and transmitters measure, monitor, and display fluid levels in a tank, drum, or container. These level sensors are immersed into a liquid stored in a container to provide volume measurements and monitor levels. Float-style liquid level sensors slide up and down the sensor's shaft to measure the remaining fluid volume within a storage container. Capacitive liquid level sensors use tube-encased capacitors for monitoring levels. Guided wave radar liquid level sensors generate electromagnetic signals that travel up and down a tube-encased probe to measure and monitor levels.