NIOSH Research Aimed At Reducing Underground Mining Mishaps

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NIOSH Research Aimed At Reducing Underground Mining Mishaps Powered By Docstoc
					 Mine Illumination
Solid-State Lighting

  Dr. John J. Sammarco
   Pittsburgh Research Laboratory
 Why is lighting important?
 Age and vision

 History of lighting

 Lighting safety & accidents

 High brightness light emitting diodes
  (HB LEDs)
 NIOSH lighting research
      Why look at mine lighting?

 Mining…“the most difficult lighting
  environment in the world”

Illumination Engineering Society of North America, 2003.
Why look at mine lighting?
   Miners depend heavily on visual cues to spot hazards
   Aging workforce
   Accidents
         Age Effects on Vision
   Night vision decreases with age
    • Smaller pupil
    • Eye less able to adapt to light
    • Fewer rod receptors
    • Cloudy eye lens
             Age Effects on Vision
    Yellowing of Lens
     (age in years)

                                 Average miner 43 yrs old

    Degradation of lens        40% less light than 20 yrs old
  decreases effective light
level and effective contrast
      (due to scatter)
     Why look at mine lighting?
   Improved lighting may help miners avoid accidents:
    • Slip/trip/falls
    • Falls of ground
    • Striking/pinning

   An MSHA study of metal/nonmetal mining concluded that
    current lighting systems are inadequate.
        Safety & Lighting

The percentage of accidents declines as illuminance is
   increased in industrial (non-mining) work areas
                   Source (Walton et al., 2005)
A Brief History of Lighting

 Candle holders
 with candles
              Oil Lamps

Oil wick lamps improved safety
by containing open flames. Costs
were also lower, and miners
found them easier to use than

                 Photos: Royal BC Museum, British Columbia, Canada,
                 Carbide lamps
The transition to helmet-mounted
lighting began with the introduction
of the carbide lamp.

                        Photo: Royal BC Museum, British Columbia, Canada,
                        Quotation: Where the Sun Never Shines, Priscilla Long, Paragon House, New York, 1989.
      Incandescent Lights
The introduction of the
incandescent lamp eliminated
concerns about open
flames within the mine.
The light from a small, steadily
burning incandescent filament
was much more controllable
than the light from an open
flame. Enclosed within a
directional reflector, it became
the standard, unchanged to
this day.

                     Photos: Royal BC Museum, British Columbia, Canada,,
                     Cape Breton Mine Museum,
What is light?
      What is light?
Electromagnetic radiation
            Light Spectrum
   White light from LEDs
    • Shorter wavelenghts
    • Bluish-white light
    • Better depth perception
    • Better color rendering
    • Better visual performance
Spectral Power Distribution
        Lighting technologies
Type           Life     Cost    Specular* color Efficiency           Shock proof
               (hrs)            temp.           (lumens/watt)

Incandescent 1,500      $7          2800oK             14                 no

Halogen        2,500    $6          3200oK             24                 no

HID            10,000   $20         4000oK             80                 no

Solid-state    50,000   $8          5500oK             70                yes
LED            +                                 (prototypes @

    •Lower specular color temperatures indicate a yellowish light;
    •higher temperatures indicate a whiter light.
     Light Emitting Diodes (LEDs)
LEDs are semi-conductors; they don't have a filament that will burn out.
They are illuminate by the movement of electrons in a semiconductor.


    Light Emitting Diodes (LEDs)

• Advantages:
1. Lower power requirements
2. Long Life (>50,000 hours)
3. Small size
4. Sturdy
5. “White, shorter
   wavelength” light
Mine Lighting Research
Reducing underground mining
   mishaps by improving
     mine illumination
         Project Scope
Underground lighting:
 Cap lamp (coal)
 Preblast lighting (metal/nonmetal)
 Machine lighting (coal)
                          Cap Lamps
       LED Cap Lamp                              Additional Personal lighting
2 lb. battery, 5 year LED life

                                 5 lb. battery
Machine Lighting
Preblast Lighting
        inspect roof & back
        loading of explosives
        Specific aim summary
   Does the color (spectral power distribution)
    from white LEDs:
    • Improve visual performance?
    • Reduce glare?

   Can advantages of LEDs (small, robust, high
    efficiency, etc) enable new designs to:
    • Improve visual performance?
    • Reduce glare?
    • Realize new safety applications?
Mine Illumination Lab
Glare tests
Peripheral motion detection
Slip/trip/fall hazards
                                Mean time to detect an object
                                Incandescent cap lamp was slowest
Mean detection time (seconds)

                                3                         Incandescent
                                2                         LED
                                                          Prototype LED
                                          Cap lamp type
Lighting prototypes

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