The Testo Sensor LD Ultrasonic Leak Detector is designed to identify pressurized gas leaks in industrial pipe systems by detecting ultrasonic frequencies (40 kHz ±2 kHz) generated by escaping gases. The device converts these inaudible ultrasonic signals into audible frequencies that can be heard through included sound-proof headphones, enabling detection of even minor leaks from several meters away in noisy industrial environments. An integrated laser pointer (645-660 nm, <1 mW) provides precise leak localization, while the system meets ASTM E1002-05 Class I instrument requirements for ultrasonic leak testing.

The detector features a 3.5-inch TFT touchscreen for intuitive operation and incorporates an automatic level function that adjusts sensitivity to ambient conditions while filtering background noise. Minimum sensitivity allows detection of 0.1 l/min leaks at 6 bar pressure from 5 meters distance. The unit operates continuously for over 10 hours on its rechargeable lithium-ion battery, with a 4-hour charging time via external charger. Data logging capability is provided through a 2 GB SD memory card, and the device functions across an operating temperature range of 23 to +122°F.