The NPL-100 is a sophisticated instrument for locating non-metallic water pipelines.
Once the vibrator is attached to the outlet of a fire hydrant or pipe fitting, the NPL-100 then sends a sound wave through the water in the pipe.
This sound wave is detected by the NPL-100's sensitive ground microphone (receiver), permitting accurate tracking of the pipeline. The vibrator's signal intensity and frequency can be remotely controlled from the receiver to find the optimum resonance of the pipeline. The NPL-100 has an automatic adjustment function for tuning in the resonance frequency of each pipe.