Besides a visual inspection upon disassembly, what method can be used to check for suspected leakage through a heat transfer plate of a plate type heat exchanger?

Correct Answer: Option C — One side of the plate is cleaned and sprayed with a fluorescent dye penetrant, and the other side is viewed with an ultra-violet light.

Fluorescent dye penetrant is a non-destructive testing method used to identify microscopic cracks or pinholes in heat transfer plates. When applied to one side, the dye migrates through defects; viewing under ultra-violet light causes the penetrant to fluoresce, clearly highlighting the location of the leak path.