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DPCNews 040 - Fluorescence vs Phosphorescence / Degreasing prior to PT / Diving in fluorescent penetrant
November 2011
Our redesigned monthly DPCNewsletter draws your attention on the papers published on this Website at the same time, or reminds you of some papers already published (all of them are still available!) on the same topics as those dealt with in the new papers.
The URL address of our Website is:
http://www.ressuage-magnetoscopie-penetranttesting-magnetictesting-dpc.info
We recommend you put it in your “Favorites” list.
Underneath, find the list of the new papers that you can read this month on our Website:
In the "Edito" section
Fluorescence vs Phosphorescence
Do you really know the difference between fluorescence and phosphorescence?
Even nowadays, in the 21st century, the difference between fluorescence and phosphorescence as defined underneath is in the minds of many engineers, trainers, etc ...
• Fluorescence is an emission of light that disappears with the end of excitation.
• Phosphorescence is an emission of light that goes on for some time after the end of excitation.
We are happy to have been in contact with Bernard VALEUR, a physicist and a chemist, emeritus professor in the Conservatoire National des Arts et Métiers (CNAM, as per its French acronym. One of the most prestigious engineers schools in France) in Paris (France).
Bernard VALEUR is a renowned specialist of molecular fluorescence, and he is known throughout the world, thanks to the books he released on this topic.
Indeed, as Bernard VALEUR writes, "the difference is based on experimental data dating back to the 19th century!"
Reading this editorial, you will know the real difference between fluorescence and phosphorescence. Further, you are given in the reference section the titles of his books, for more detailed information.
In the "NEWS" section
Degreasing prior to penetrant testing
Degreasing prior to PT is an ESSENTIAL and DECISIVE step to ensure a reliable inspection.
In fact, pollutants such as oils and fats, as any other material may clog discontinuities and prevent penetrant to do its job properly. As good as penetrant materials or inspectors are, nothing can be done against.
This paper presents the different degreasing methods, their advantages and disadvantages, and some recommendations.
In the "Oldies but goodies" section
Diving in fluorescent penetrant for special effects (FX)
This mini-story occurred on a Friday late afternoon, just when there is no time left to begin a new task, except for talking with colleagues.
To be comfortable while exchanging views on the next football match, what else can be more comfortable than a chair? What if none is available?
In the "Mail inbox" section
A too high fluorescent background brightness?
Which criteria make it possible to claim that the fluorescent background is too high?
One of our readers told us that a NADCAP auditor has issued a Non-Compliance Report (NCR) due to a too high background. Which were the criteria the auditor relied upon for this decision?
Our response may be useful to PT inspectors, auditors and auditees.
We, Pierre CHEMIN and Patrick DUBOSC, welcome any comment, any idea. If you have some examples you would like to see discussed here, please give us all the useful indications. If you require confidentially, we would modify locations, names and some parameters to prevent any traceability.
Nevertheless, we are convinced that our site may be a kind of surge-valve: the topic is NOT to target this company, or that auditor; but it is always to make users think, to make them ask themselves, or others, the right questions.
We may also give advice, once again on a confidential basis if needed: please, feel free to ask questions, to document our data basis: about Material Safety Data Sheets (MSDS), about environment, a chemical name you don't understand, a Penetrant process you have heard about, etc.
We have plenty of examples, some being out of all the specifications/standards, which led to the discontinuities detection, when the "current, normal, processes" prevented discontinuity finding.