Panasonic SQ4 safety liquid leak sensor reports the occurrence of an incipient liquid leak to the production supervisor and perform equipment maintenance after removing any work in progress. By quickly detecting even small liquid leaks (incipient leaks), personnel can perform preventive maintenance or plan maintenance, thereby reducing both downtime and damage to work in progress. In the event of a high-volume liquid leak (an abnormal liquid leak), the target equipment is stopped immediately to ensure safety. On the bottom of the sensor are two detection units, one located at the front and one at the center. If a liquid leak occurs in front of the sensor, the front detection unit will detect even a small incipient leak. When the leak increases in volume and reaches the center of the sensor, it will be detected as an abnormal leak. While previous implementations of two-stage liquid leak detection have relied on two separate sensors installed at different heights, the SQ4 delivers the same full-featured detection capability in a single sensor unit. In addition to detecting liquid leaks, the SQ4 can detect both human error (such as a failure to install the sensor) and sensor malfunctions. If the sensor itself or the sensor and its mounting bracket have become dislodged, have been improperly installed, or are suffering from a broken cable connection, light from the emitter will not reach the receiver, causing the device to generate the same output as if a liquid leak had occurred.