What is the primary distinction between dry and wet magnetic particle inspection?

The primary distinction between dry and wet magnetic particle inspection lies in the form of the magnetic particles used during the inspection process. In dry magnetic particle inspection, powder particles are applied directly to the magnetic field generated on the surface of the material being inspected. These particles adhere to any magnetic leakage fields caused by surface or near-surface discontinuities, allowing for the detection of flaws.

In contrast, wet magnetic particle inspection utilizes a suspension of magnetic particles in a liquid carrier. This liquid can help disperse the particles more evenly over the surface and can enhance the visibility of indications due to the fluid's ability to spread and coat the inspected area effectively.

Understanding this distinction is essential for selecting the appropriate method based on specific inspection requirements, including the type of material, the nature of the discontinuities being evaluated, and the desired sensitivity of the inspection. The option regarding wet MPI being only for fluorescent inspection is not accurate, as wet MPI can also utilize non-fluorescent particles.