Mine Illumination and Solid-State Lighting.

 

Mine Illumination

and

Solid-State Lighting

Dr. John J. Sammarco

NIOSH

Pittsburgh Research Laboratory

Agenda

◆ 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.

◆ Miners depend heavily on visual cues to spot hazards

◆ Aging workforce

◆ Accidents

Why look at mine lighting?

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)

Degradation of lens

decreases effective light

level and effective contrast

(due to scatter)

Average miner 43 yrs old

40% less light than 20 yrs old

◆ 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.

Why look at mine lighting?

Safety & Lighting

The percentage of accidents declines as illuminance is

increased in industrial (non-mining) work areas

Source (Walton et al., 2005)

Candle holders

with candles

A Brief History of Lighting

Oil wick lamps improved safety

by containing open flames. Costs

were also lower, and miners

found them easier to use than

candles.

Photos: Royal BC Museum, British Columbia, Canada, http://www.royalbcmuseum.bc.ca/

Oil Lamps

Photo: Royal BC Museum, British Columbia, Canada, http://www.royalbcmuseum.bc.ca/

Quotation: Where the Sun Never Shines, Priscilla Long, Paragon House, New York, 1989.

The transition to helmet-mounted

lighting began with the introduction

of the carbide lamp.

Carbide lamps

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, http://www.royalbcmuseum.bc.ca/,

Cape Breton Mine Museum, www.minersmuseum.com

Incandescent Lights

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

(hrs)

Cost Specular*

 color

temp.

Efficiency

(lumens/watt)

Shock proof

Incandescent 1,500 $7 2800oK 14 no

Halogen 2,500 $6 3200oK 24 no

HID 10,000 $20 4000oK 80 no

Solid-state

LED

50,000

+

$8 5500oK 70

(prototypes @

110)

yes

•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.

LED’s

Luminaires

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

NIOSH

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

2 lb. battery, 5 year LED life

Additional Personal lighting

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?

NIOSH

Mine Illumination Lab

Glare tests

Peripheral motion detection

Slip/trip/fall hazards

Mean time to detect an object

Incandescent cap lamp was slowest

Lighting prototypes

Questions