Common tools and techniques used for leak detection in HVAC refrigeration systems include electronic leak detection, soap bubble method, and halogen leak detectors. Electronic leak detection uses sensors to detect refrigerant leaks, while the soap bubble method involves applying a soap solution to suspect areas to identify leaks. Halogen leak detectors use a UV light to detect halogen gases, such as chlorine or fluorine, which are present in refrigerants. These tools and techniques enable HVAC professionals to precisely identify and locate leaks in the system.