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Technical Discussions
David Smart
Sales,
SmartChem Industries Pty Ltd, Australia, Joined Jan 2001, 6

David Smart

Sales,
SmartChem Industries Pty Ltd,
Australia,
Joined Jan 2001
6
07:23 Jan-17-2001
UV/ White Light Conditions- Visual Acuity

Hello NDTers

I would be interested to know if anybody knows of any documented research relating to ultraviolet light intensity and the affect it has on the fluorescent intensity of fluorescent inspection media(dye pen/mag)

Current fluorescent penetrant and magnetic particle process specifications generally nominate a minimum UV light output of 1000 microwatts at 38cm under darkroom conditions having a maximum ambient white light of 20 Lux (2 footcandles). We have been working with high intensity UV lights with outputs exceeding 50,000 microwatts at 38cm and it would be beneficial to be able to relax the ambient white light restriction proportionally for higher intensity UV inspection lamps.

We have conducted our own empirical trials using Eishin nickel chrome cracked panels and Sherwin PSM-5 panels comparing indications in the darkroom under standard viewing conditions using a conventional UV light and in daylight using high intensity UV light. We found that the indications appeared clearer and brighter when using the high intensity UV light even when the panels were viewed in normal daylight.

I am aware of an article in BINDT's Insight magazine (volume 39 No 12 December 1997)written by Meinhard Stadthaus, which states that "The energy of the emitted radiation(luminance of the indication) is proportional to the exciting energy in the region of interest" and further states "it will be confirmed that no saturation effect of the fluorescence can be observed" we understand that these trials were only carried out up to 10,000 microwatts.

Whilst we are interested in any research relating to the above, we are also interested in knowing of any specifications which allow higher ambient white light in the inspection area where higher intensity UV lamps are used for inspection purposes and what relationship there might be between the UV/White light intensities.

Any information would be greatly appreciated.

Regards
David Smart
PH: #612 9896 0700
Fax:#612 9896 0634




    
 
 
Dave Wilkes
Dave Wilkes
08:59 Jan-17-2001
Re: UV/ White Light Conditions- Visual Acuity
When testing with MPI, the background light problem
can be solved by using Flourescent Inks designed for
daylight use.

I do not know of any manufacturers producing Dye Pen
Flourescents that work in daylight, but if they are
available, this could solve your problem.

Dave Wilkes
Asst Editor
www.ndtcabin.com "The internet magazine for ndt technicians"



    
 
 
David Smart
Sales,
SmartChem Industries Pty Ltd, Australia, Joined Jan 2001, 6

David Smart

Sales,
SmartChem Industries Pty Ltd,
Australia,
Joined Jan 2001
6
03:08 Jan-17-2001
Re: UV/ White Light Conditions- Visual Acuity
: When testing with MPI, the background light problem
: can be solved by using Flourescent Inks designed for
: daylight use.

: I do not know of any manufacturers producing Dye Pen
: Flourescents that work in daylight, but if they are
: available, this could solve your problem.

: Dave Wilkes
: Asst Editor

: www.ndtcabin.com "The internet magazine for ndt technicians"

Dear Dave,

Many thanks for your prompt response.

We are aware of the daylight fluorescent MPI fluids, however our question related to the use of conventional fluorescent media with ambient light greater than 20 lux.

The fact that higher UV intensity creates increased fluorescent brightness in the media, we are interested in any research or specifications which confirm that under high UV intensity the inspection can be carried out under higher ambient white light without any loss in sensitivity.

Once again many thanks for your help.

Regards
David Smart


    
 
 
Kris Smestad
Kris Smestad
03:46 Jan-18-2001
Re: UV/ White Light Conditions- Visual Acuity
All you need to do is prove to your customer(s) that any one of your inspectors can consistantly visually identify an indication that is equal to or smaller than the specified minimum relevant indication. For example, if your minimum relevant is .010 inches, prove that an inspector can always detect a .005 in the brightest ambient conditions that he will encounter. Obtain an exemption for the ambient white light requirement for your company's written practice.
You can do the same for the requirement that specifies the amount of time that an inspector's eyes need to adapt to the dark. He can begin inspecting when he can see a defect of a known size that is smaller than minimum relevant, instead of the 3 minute requirement. Just about any customer will buy it if you can prove it.

-Kris

: Hello NDTers

: I would be interested to know if anybody knows of any documented research relating to ultraviolet light intensity and the affect it has on the fluorescent intensity of fluorescent inspection media(dye pen/mag)

: Current fluorescent penetrant and magnetic particle process specifications generally nominate a minimum UV light output of 1000 microwatts at 38cm under darkroom conditions having a maximum ambient white light of 20 Lux (2 footcandles). We have been working with high intensity UV lights with outputs exceeding 50,000 microwatts at 38cm and it would be beneficial to be able to relax the ambient white light restriction proportionally for higher intensity UV inspection lamps.

: We have conducted our own empirical trials using Eishin nickel chrome cracked panels and Sherwin PSM-5 panels comparing indications in the darkroom under standard viewing conditions using a conventional UV light and in daylight using high intensity UV light. We found that the indications appeared clearer and brighter when using the high intensity UV light even when the panels were viewed in normal daylight.

: I am aware of an article in BINDT's Insight magazine (volume 39 No 12 December 1997)written by Meinhard Stadthaus, which states that "The energy of the emitted radiation(luminance of the indication) is proportional to the exciting energy in the region of interest" and further states "it will be confirmed that no saturation effect of the fluorescence can be observed" we understand that these trials were only carried out up to 10,000 microwatts.

: Whilst we are interested in any research relating to the above, we are also interested in knowing of any specifications which allow higher ambient white light in the inspection area where higher intensity UV lamps are used for inspection purposes and what relationship there might be between the UV/White light intensities.

: Any information would be greatly appreciated.

: Regards
: David Smart
: PH: #612 9896 0700
: Fax:#612 9896 0634




    
 
 

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