where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

NDTSS - Non Destructive Testing Society of Singapore
Visit us at SINCE 2019
3563 views
Technical Discussions
Shahid Nisar
Engineering,
Saudi Arabia, Joined Feb 2009, 134

Shahid Nisar

Engineering,
Saudi Arabia,
Joined Feb 2009
134
06:06 Mar-01-2017
To Reduce Dark Adaptation Time

For operators working in closed booths for fluorescent MPI. How can be dark adaptation time be reduced if he goes out and come back for re work. Can for this purpose any non-Photochromic dark glasses are available ?

 
 Reply 
 
Hamid Reza
,
Canada, Joined Oct 2016, 68

Hamid Reza

,
Canada,
Joined Oct 2016
68
11:33 Mar-01-2017
Re: To Reduce Dark Adaptation Time
In Reply to Shahid Nisar at 06:06 Mar-01-2017 (Opening).

Dear Shahid Nisar,

What does the standard you are using say?

ASTM E1444 2016 e1 Standard Practice for Magnetic Particle Testing (latest version) says:

6.5.1 Eye Glasses—When using fluorescent materials, personnel
shall not wear eye glasses that are photochromic or that
have permanently darkened lenses. This is not intended to
prohibit the use of eyeglasses with lenses treated to absorb
ultraviolet light.

6.5.2 Dark Adaptation—Personnel must wait at least one
minute after entering a darkened area for their eyes to adjust to
the low-level lighting before performing fluorescent magnetic
particle testing.

ASTM E709, 2015 says Standard Guide for Magnetic Particle Testing (latest version):

7.1.3 Dark Area Eye Adaptation—The generally accepted
practice is that an inspector be in the darkened area at least one
(1) minute so that his or her eyes will adapt to dark viewing
prior to examining parts under UV illumination. (Warning—
Photochromic or permanently tinted lenses should not be worn
during examination.)

ISO 3059, 2012, Non-destructive testing — Penetrant testing and magnetic particle testing — Viewing conditions(latest version) says:

5.3: Permanently tinted spectacles, neutral density glasses or those which darken under inspection conditions shall not be worn, except for techniques involving white background and very high levels of daylight (generally above 20 000 lx) which can reduce indication detectability. In this case, the use of neutral density glasses are permitted. Care shall be taken under such conditions.

6.3: Permanently tinted spectacles or those which darken under inspection conditions shall not be worn.

ASME Sec V, 2015, Article 7, Paragraph T-777.2 says:

(b) Examiners shall be in a darkened area for at least
5 min prior to performing examinations to enable their
eyes to adapt to dark viewing. Glasses or lenses worn
by examiners shall not be photochromic or exhibit any
fluorescence.

-----

Recommended practice is to wait for 5 to 10 minutes.

You might want to read "Principles of Magnetic Testing" ,First edition, by Carl E. Betz, Chapter 15 is very comprehensive. Your questions is specifically answered in section 21 of that chapter.

This is also a good read: https://en.wikipedia.org/wiki/Adaptation_(eye)#Dark_adaptation

 
 Reply 
 
Rick Lopez
R & D,
John Deere - Moline Technology Innovation Center, USA, Joined Jul 2011, 188

Rick Lopez

R & D,
John Deere - Moline Technology Innovation Center,
USA,
Joined Jul 2011
188
23:13 Mar-01-2017
Re: To Reduce Dark Adaptation Time
In Reply to Shahid Nisar at 06:06 Mar-01-2017 (Opening).

You raise an interesting question, Shahid. Pirates are said to have worn a patch over one eye so that they could maintain dark adaptation in the covered eye when they went out into the bright daylight; the dark-adapted eye could quickly be used when they went below deck. It's unlikely that an NDT manager would prefer a 1-eyed inspector, but I wonder if anyone has ever explored the use of a pair of dark neutral density glasses to protect the state of dark adaptation during a short excursion into daylight (not used during inspection)? I happened to have an old pair of UVEX Infra-Dura 5.0 (2% visible light transmission) for a quick trial, and in spite of this low visible light transmission I felt I could easily walk around and function in a bright factory. While a cursory experiment is one thing, it's possible that a NADCAP auditor (i.e. aerospace) or other may ask you to actually prove that adaptation hasn't been lost...and there is the difficulty. No easy adaptation evaluation tool exists (that I'm aware of), so you'd likely be left performing a probability of detection study. Such a study would be tricky since you'd be comparing effects that change quickly with time. The easiest route is likely to just rely on the guidance you're mandated to work to, or that offered by Eager above.

1
 
 Reply 
 
David Harvey
David Harvey
01:22 Mar-02-2017
Re: To Reduce Dark Adaptation Time
In Reply to Rick Lopez at 23:13 Mar-01-2017 .

Once upon a time, the dark adaptation time was 5 minutes. It then changed, rather arbitrarily and without data, to one minute. I would submit that one minute is not really adequate, and that less than that would be a tough sell.

There are many variables in just what adaptation is needed. How bright is the light outside the booth? What is the age of the inspector? How powerful is the black light and how large are the expected indications? The list could go on...

I would recommend against abbreviating the one minute adaptation time. One minute is not that long...

1
 
 Reply 
 
Shahid Nisar
Engineering,
Saudi Arabia, Joined Feb 2009, 134

Shahid Nisar

Engineering,
Saudi Arabia,
Joined Feb 2009
134
15:23 Mar-02-2017
Re: To Reduce Dark Adaptation Time
In Reply to Shahid Nisar at 06:06 Mar-01-2017 (Opening).

Let me elaborate the situation - During online MPI-fluorescent of tubular products, the inside of MPI booth is exposed to outside light when pipe enters and goes out . the maximum visible light intensity measured during outside light exposure is less than 10 lux. so in this case shall the dark adaptation requirements persist?

 
 Reply 
 
Rick Lopez
R & D,
John Deere - Moline Technology Innovation Center, USA, Joined Jul 2011, 188

Rick Lopez

R & D,
John Deere - Moline Technology Innovation Center,
USA,
Joined Jul 2011
188
16:51 Mar-02-2017
Re: To Reduce Dark Adaptation Time
In Reply to Shahid Nisar at 15:23 Mar-02-2017 .

I'm not sure what you mean by "online"; I'll assume you mean what I would term "inline", which would suggest that you have pipe coming into the booth via overhead crane, conveyor line, etc. If that is the case, is it feasible to engineer a light-blocking solution that the pipe can pass through? Many years ago I recall visiting an aircraft MRO facility that had implemented spring-loaded doors (for the hoist motor at ceiling height) and strip linear brushes around the rest of the openings where hoist chain passed. In this case the actual parts passed through a penetrant testing dust storm cabinet with doors on both ends and linear brushes across the top, but I wonder if a similar idea could be useful to you? Example brushes from a quick web search (black was used in above example): http://www.sitbrush.com/Industrial-Technical-Brushes/Linear-Strip-Industrial-Brushes.php

As I mentioned before, I think you'll have a hard time answering the question of whether adaptation state has been lost, so just avoiding the exposure would be best course of action.

Regards

1
 
 Reply 
 
Hamid Reza
,
Canada, Joined Oct 2016, 68

Hamid Reza

,
Canada,
Joined Oct 2016
68
18:10 Mar-02-2017
Re: To Reduce Dark Adaptation Time
In Reply to Shahid Nisar at 15:23 Mar-02-2017 .

Dear Shahid Nisar,

You did not mention the standard you are working with.

At least according to the ISO 3059 you might not be able to perform the test. Because there might be other sources of visible light in the operators field of vision. The 10 lux visible light on the part you mentioned has nothing to do with eye adaptation to the darkness.

These standard say:

ISO 3059, 2012, Non-destructive testing — Penetrant testing and magnetic particle testing — Viewing conditions(latest version) says:

6.3:
For inspection, the UV-A irradiance shall be 10 W/m2 (1 000 μW/cm2) or greater and the illuminance 20 lx
or less on the test surface. The measurements shall be carried out ___under working conditions___ with the UV-A source turned on and stabilized.

There shall be no glare or other source of visible light or UV-A radiation within the operator’s field of vision. Ambient visible light levels shall be 20 lx or less.

ASTM E1444 2016 e1 Standard Practice for Magnetic Particle Testing (latest version) says:

7.3.1.2 Ambient Visible Light—Fluorescent magnetic particle
examinations shall be performed in a darkened area with
a maximum ambient visible light level of 2 fc [22 lx] measured
at the part surface.

ASTM E709, 2015 says Standard Guide for Magnetic Particle Testing (latest version):

7.1.1.2 Ambient Visible Light—The intensity of ambient
visible light in the darkened area where fluorescent magnetic
particle testing is performed is recommended to not exceed 2
foot candles (21.5 lux).

 
 Reply 
 
Hamid Reza
,
Canada, Joined Oct 2016, 68

Hamid Reza

,
Canada,
Joined Oct 2016
68
18:51 Mar-02-2017
Re: To Reduce Dark Adaptation Time
In Reply to Hamid Reza at 18:10 Mar-02-2017 .

Also found these from: "Principles of Magnetic Testing" ,First edition, by Carl E. Betz. Chapter 15,

Section 11:

Complete darkness is of course the optimum for maximum visibility and contrast, since even minute points of light emission are readily seen in complete darkness. To secure complete darkness means a light-proof room; but in most practical applications it is not necessary to go this far in the exclusion of white light. As a matter of fact, absolute darkness is never achieved in any case, since the black light lamps give off some visible violet light. This small amount of violet light is actually not a disadvantage, as it makes it possible to see the part being handled. Indications, which glow with a bright yellow-green, are in good contrast with the violet, and are readily seen.

But again it warns you in the section 12:

Since the black light generates considerable heat, small ventilating fans in the booth are often necessary. Usually a white light is also provided to facilitate cleaning of the booth and making up baths, etc., but this light should not be turned on during inspection of parts. Even brief exposure to bright white light destroys the dark adaption of the inspector's eyes. >---- important

Thought maybe knowing these two points could help you.

Also remember, while it takes 5~8 minutes for Cones in your eyes to adapt to darkness and about 30 minutes (in total) for Rods in your eyes to adapt to darkness, it only takes about 3 to 5 minutes for your eyes to adapt fully to to light.

More information:
Light and Dark Adaptation by Michael Kalloniatis and Charles Luu
ref: http://webvision.med.utah.edu/book/part-viii-gabac-receptors/light-and-dark-adaptation/

Brushes, suggested by Rick is a brilliant idea.

By the way, thank you Rick for the information about the eye patch that pirates used! I always wondered why most of them had an eye missing ;-)

 
 Reply 
 
Shahid Nisar
Engineering,
Saudi Arabia, Joined Feb 2009, 134

Shahid Nisar

Engineering,
Saudi Arabia,
Joined Feb 2009
134
19:33 Mar-02-2017
Re: To Reduce Dark Adaptation Time
In Reply to Hamid Reza at 18:10 Mar-02-2017 .

Dear Eager
Applicable standard is ASTM E 709.
As stated by Rick I am of the opinion that if the ambient light intensity does not exceed the 21.5 Lux inside the MPI station, the inspectors dark adaptation is not lost.
The intensity of 10 lux is the ambient light reading detected inside the booth not on the testing surface but at the position where the light meter facing the exposure direction at different locations in the booth gives this maximum value.

 
 Reply 
 
Hamid Reza
,
Canada, Joined Oct 2016, 68

Hamid Reza

,
Canada,
Joined Oct 2016
68
19:59 Mar-02-2017
Re: To Reduce Dark Adaptation Time
So...

What is the maximum illuminance you get with the UV lamp off?

and

What is the maximum illuminance you get with the UV lamp on and pointed towards the area of inspection?

What is the brand and model of the magnetic ink you are using?

Have you ever tried to see if you can see the fluorescent indications in the white light with the UV-A pointed at it? I ask because I read something interesting in this book:

Magnetic Particle Inspection A practical guide, Daivd Lovejoy, 1993, Page 181:

When fluorescent particles are used there is the extra possibility to add to the contrast by carrying out inspection in a darkened area. Until relatively recently it was essential for inspection of fluorescent indications to be carried out in darkened areas, as the classical magnetic particles are not bright enough to be seen easily otherwise. Within the past 20 years magnetic particles have been developed which are up to five or more times as bright as the classical fluorescent particles under the same level of UVA (black light) illumination. In certain industries it has become accepted standard practice to use these products in full daylight or other visible light with UVA of around 1000 uW/cm2. Where these fluorescent particles have become accepted in the aerospace industry there remains the requirement for a darkened inspection area. As yet there has been little in the way of controlled comparative work reported on the effect of inspecting indications produced by these more recent particles in levels of white light from 10 lux to 500 lux and 1000 lux.

I have seen that Magnaflux Fluorescent magnetic ink, 14HF, is visible under UVA lamp in a room with strip lights on (a very bright room indeed!). So this might be a way to see how bright can your ink fluoresce. Just to test it!!!
 
 Reply 
 
Shahid Nisar
Engineering,
Saudi Arabia, Joined Feb 2009, 134

Shahid Nisar

Engineering,
Saudi Arabia,
Joined Feb 2009
134
20:08 Mar-02-2017
Re: To Reduce Dark Adaptation Time
Eager Instead the ink might fluoresce at high lux values but per ASTM E 709 , 21.5 Lux is the limit for ambient light .
 
 Reply 
 
Dent
Consultant, NDE Manager NDELevel III/3
NDT Consultant, Canada, Joined Nov 1998, 248

Dent

Consultant, NDE Manager NDELevel III/3
NDT Consultant,
Canada,
Joined Nov 1998
248
21:04 Mar-02-2017
Re: To Reduce Dark Adaptation Time
In Reply to Shahid Nisar at 06:06 Mar-01-2017 (Opening).

See Appendix III of ASME Section V Article 7. It has rules for performing MT in an undarkened area using Yokes.
Maybe this will help.

1
 
 Reply 
 
Gerald Reams
Engineering,
Industry, USA, Joined Aug 2012, 181

Gerald Reams

Engineering,
Industry,
USA,
Joined Aug 2012
181
21:35 Mar-02-2017
Re: To Reduce Dark Adaptation Time
In Reply to Shahid Nisar at 15:23 Mar-02-2017 .

Specified ambient light restrictions are the background white light level allowed for the inspection under ultraviolet light. This is primarily associated with the area of interest under examination.

The light leak coming into the booth from the entrance and exit caused by the pipe can affect the physiology of the Inspector's eyes if it in their line of sight (direct and peripheral) by dilation response; even at low levels.

I agree that brushes at the entrance and exit of the booth around the pipe should eliminate the problem.

 
 Reply 
 
Hamid Reza
,
Canada, Joined Oct 2016, 68

Hamid Reza

,
Canada,
Joined Oct 2016
68
22:11 Mar-02-2017
Re: To Reduce Dark Adaptation Time
In Reply to Gerald Reams at 21:35 Mar-02-2017 .

Dear Dent,

You mentioned a very useful part of ASME sec V standard. I completely forgot that there was such an appendix:

MANDATORY APPENDIX III
MAGNETIC PARTICLE EXAMINATION USING THE YOKE
TECHNIQUE WITH FLUORESCENT PARTICLES IN AN
UNDARKENED AREA

But one question. Are you recommending reading this appendix as a guidance only? Since it is related to the BPVC and Shahid Nisar is using ASTM E709....


Another thought:

I think using black strip covers, like those that are hung at the entrance and end of the X-ray Baggage Scanners are also a good alternative for light proofing the entrance.

 
 Reply 
 

Product Spotlight

NEW - TD Focus-ScanRX

The NEW Next Generation Advanced UT platform, TD Focus ScanRX - Also available as a card stack solut
...
ion. Key Improvements 1. Data acquisition is significantly faster than current design 2. Better aesthetic – closely aligns with HandyScan RX 3. Improved IP rating (Target IP66) 4. Ruggedized housing 5. Connectors are protected from impact and ingress 6. Integrated stand and separate retractable handle easy to keep clean) 7. Touchscreen with ruggedized display glass 8. 3-Axis encoder input
>

Semi-Automated Phased Array Immersion System for Small Composite Parts

Turn-key semi-automated system as an improved and affordable solution for inspection of small comp
...
osite parts. Includes support table, immersion tank, scanner, PA instrument, PC, Analysis software, database, wedge management and other options.
>

Aerospace Systems - Automated Ultrasonic Inspection

USL are specialists in the design and manufacture of turnkey ultrasonic inspection systems for aer
...
ospace applications. From monolithic composites to complex honeycomb structures. This video shows just a few examples of what is possible, find out more at: www.ultrasonic-sciences.co.uk
>

High-performance Linear Phased Array Probes

Available to order from stock in a range of 5MHz – 7.5MHz and from 16 to 64 elements. Designed w
...
ith piezo-composite elements, Phoenix phased array probes provide high-resolution imaging to maximise sensitivity; accurate ultrasonic detection and sizing of defects in welds; and effective corrosion mapping. Housed in a rugged stainless steel case for on-site industrial NDT applications.
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window