Fluorescent Penetrants: What do you know about the liquid penetrant?
Fluorescent Penetrants: The liquid penetrant (or control Penetrant Testing PT) is a product used in non-destructive testing of materials; they give the same name to the technical control. This method was introduced for the first time in the period before the Second World War; officially the authorship is attributed to the brothers Robert and Joseph Switzer which led to the first studies on the control PT to improve its characteristics. The need to introduce a different control examination with magnetic particles was linked to the introduction of light alloys in diffusion between the first and the second half of 1900.
The non-destructive testing of such dye penetrant inspection procedure is a superficial integrity of a ferrous or non-ferrous piece and possibly non-porous surface in the analysis. The penetrant is sprinkled by spraying, brushing or dipping, allowing the capillary action to act for the necessary time. Subsequently, the penetrant excess is removed. The control method PT is based on the penetration of a liquid to determinate certain characteristics of capillarity, viscosity, wettability (or surface tension) and density.
In addition to the classic method of control with red / purple penetrating, other methods are more sophisticated and designed for special needs; we include here for example the control with fluorescent penetrants where the penetrant is not visible to the naked eye after the application of the detector, but requires the use of a black light or ultraviolet light to highlight the fluorescence.
Types of liquid penetrant:
- Colored penetrants: are inspected with naked eye, you just have to have a good source of white light and they have less sensitivity.
- Fluorescent penetrants: are inspectedwiththe aid of aUV lamp(black light), without this, are invisible to the eye and they havegreater sensitivity.
- Water-washable penetrants: for cleaning and removal of excess is used simply water. They are very economical to use.
