The DefHi probe overcomes many of the down sides of conventional tube inspection techniques. The probe uses oval coils for a higher coil density, which enables detecting defects and estimating their circumferential length and position, something that a standard bobbin probe can’t do. Bobbin probes are limited to the number of channels of the test instrument — usually 4 or 8 — which makes their sensitivity too low to be adequate. Multiplexing the oval coils makes it possible to accommodate up to 128 channels giving it a much greater sensitivity.
This high-definition sensitivity is uniform and can detect defects oriented in any direction, which can’t be matched by other so-called array probes (non-multiplexed array probes) or air-conditioning (AC) probes.
Thus, compared to standard ECT bobbin probes, the DefHi can discriminate between the various complex geometries inside heat exchanger and condenser tubing to allow accurately detecting, sizing, and characterizing small-volume longitudinal and circumferential cracks.