Underground Coal Mine Lighting Handbook

Bureau of Mines Information Circularll986

Underground Coal Mine Lighting Handbook

(In Two Parts) 1. Background

Compiled by W. H. Lewis

UNITED STATES DEPARTMENT OF THE INTERIOR

Information Circular 9073

Underground Coal Mine Lighting Handbook

(In Two Parts) 1. Background

Compiled by W. H. Lewis

UNITED STATES DEPARTMENT OF THE INTERIOR Donald Paul Hodel, Secretary BUREAU OF MINES Robert C. Horton, Director

Library of Congress Cataloging-in-Publication Data

Main entry under title: Underground coal mine lighting handbook.

(Information circularNniled States Department of the Interior, Bureau of Mines; 9073)

Bibliographies. Supt. of Docs. no.: I 28.27: Contents: v. 1. Background-v. 2. Application.

1. Mine lighting. 2. Coal mines and mining.

I. Lewis, W. H. (William H.) 11. Series: Information circular (United States. Rurcau

of Mines); 9073.

TN309.U47

1986

CONTENTS

Page

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Chapter 1.-Coal mine lighting . . . . . . . . . . . . . 2

History . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 P~oductivity . . . . . . . . . . . . . . . . . . . . . . . 4 Opinion surveys . . . . . . . . . . . . . . . . . . . . . 4 Major technical considerations . . . . . . . . . . . . 4 Chapter 2....Light physics . . . . . . . . . . . . . . . . . 5 Perception . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Physical behavior . . . . . . . . . . . . . . . . . . . . . 6 Absorption . . . . . . . . . . . . . . . . . . . . . . . . 7 Reflection . . . . . . . . . . . . . . . . . . . . . . . . . 7 Transmission . . . . . . . . . . . . . . . . . . . . . . . 9 Quantifying light energy . . . . . . . . . . . . . . . . 10

Illumination and the cosine law . . . . . . . . . . 11 Inverse square law . . . . . . . . . . . . . . . . . . . 13 Candlepower curves and their uses . . . . . . . 14 Average luminance and candlepower curves . . 18 Perfectly diffuse reflectors and emitters . . . . 19

Relationship among reflectance,

illumination. and luminance . . . . . . . . . . . 19

Limits of agreement between luminance

and perceived brightness . . . . . . . . . . . . . . 20

Chapter 3.-Light and vision relationships . . . . . 20

The eye and how it works . . . . . . . . . . . . . . . 20 Parts of the light control system . . . . . . . . . 20

Parts of the receiver-decoder system . . . . . . . 21 Light control system operation . . . . . . . . . . . . 21

Light focusing and accommodation . . . . . . . . 21 Pupil size . . . . . . . . . . . . . . . . . . . . . . . . . 21 Other light cont.rol functions . . . . . . . . . . . . 22 Receiver-decoder system operation . . . . . . . . . 22

Photoreceptor function . . . . . . . . . . . . . . . . 22

Light levels needed to stimulate photo-

receptors . . . . . . . . . . . . . . . . . . . . . . . . . 22

Time and photoreceptor response . . . . . . . . .

Photoreceptor wavelength sensitivity and

the Purkinje shift a t low light levels . . . . . Adaptation . . . . . . . . . . . . . . . . . . . . . . . . Visual field and perception within the field . . . Impact of photoreceptor distribution . . . . . . . Boundaries of the visual field . . . . . . . . . . . Binocular and stereoscopic vision . . . . . . . . .

Eye and head movements . . . . . . . . . . . . . . Miner nystagmus . . . . . . . . . . . . . . . . . . . . Common visual defects . . . . . . . . . . . . . . . . .

Environmental factors affecting vision . . . . . . Contrast and seeing . . . . . . . . . . . . . . . . . .

Relationship between contrast detection

and illumination levels . . . . . . . . . . . . . . . Effect of object size . . . . . . . . . . . . . . . . . . . Effect of time . . . . . . . . . . . . . . . . . . . . . . Concept of visual acuity . . . . . . . . . . . . . . . Quantifying and measuring visibility . . . . . . Use of visibility measurements . . . . . . . . . . Consideration of performance . . . . . . . . . . .

Types of artificial illumination . . . . . . . . . . . . Typical task illumination levels . . . . . . . . . . . Color in mining . . . . . . . . . . . . . . . . . . . . . . Chapter 4.-Disability and discomfort glare . . . . Disability glare . . . . . . . . . . . . . . . . . . . . . .

Uisability glare relationships . . . . . . . . . . .

Application of the disability glare

relationships . . . . . . . . . . . . . . . . . . . . . . Discomfort glare . . . . . . . . . . . . . . . . . . . . . .

Discomfort glare equations . . . . . . . . . . . . . Visual comfort probability . . . . . . . . . . . . .

Limitations of the discomfort glare

analysis . . . . . . . . . . . . . . . . . . . . . . . . . Unit of measure abbreviations . . . . . . . . . . . . . .

ILLUSTRATIONS

1. Radiant energy (electromagnetic)spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Brightness sensitivity of the eye a s a function of light wavelength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Classification of reflectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. Curved reflectors used to control light distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. Use of surface patterns to control light distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. Effect of interreflection on net light transmission for enclosed light fixtures . . . . . . . . . . . . . . . . . . . . . . 7. Effect of changing transmission mediums on direction of light travel . . . . . . . . . . . . . . . . . . . . . . . . . . .

8. Use of curved lens to control light distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9. Illumination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10. Determining angle of incidence (0) when applying the cosine law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11. Basis of the cosine law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12. Solid angle forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13. Beam angle of mining vehicle headlight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14. Concept of luminous intensity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15. Basis of the inverse square law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

16. Candlepower curve for a typical incandescent fixture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

17. Light measurement to establish candlepower curve for a mining vehicle headlight . . . . . . . . . . . . . . . . . 18. Candlepower curve for a mining vehicle headlight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19. Geometry for performing illumination calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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