The Honeywell LLE Series liquid level sensors offer a reliable solution for single-point liquid level detection in various industrial applications. The sensor operates by utilizing a phototransistor and LED sealed within a plastic dome. When liquid covers the dome, light escapes, causing the output to switch low. It's crucial to verify fluid compatibility with polysulphone before use. These sensors are suitable for applications requiring a TTL compatible output and are designed for ease of integration into automated systems.