Leak sensors are devices that serve to provide an alarm condition or visual indication of the presence of a leak condition from a pipe or other system that contains liquids or gases. A gas detector is a device that detects the presence of gases in an area, often as part of a safety system. A gas detector can sound an alarm to operators in the area where the leak is occurring, giving them the opportunity to leave.

The sensors respond to sound generated by escaping gas at ultrasonic frequencies. Leak rate is mainly dependent on the size of the leak and the gas pressure. In most facilities the majority of process noise is in the audible range, while limited ultrasonic noise is generated in normal operation.