30 CFR § 75.1719-3 Methods of measurement; light measuring instruments.
(a) Compliance with §75.1719-1(d) shall
be determined by MSHA by measuring luminous intensity (surface
brightness).
(b) In measuring luminous intensity the following procedures shall be
used:
(1) In areas of working places specified in
§§75.1719-1(e)(1) through 75.1719-1(e)(3)
luminous intensity measurements of the face, ribs, roof, floor, and exposed
surfaces of mining equipment, shall be made with the machine idle and located
in the approximate center of the working place with the cutting, loading, or
drilling head toward the face and not more than 3 feet from the face.
(2) In areas of working places specified in
§75.1719-1(e)(4) luminous intensity
measurements may be made at any time longwall or shortwall mining equipment
is operated except that when measurements are made in the vicinity of
shearers, plows, or continuous miners, the equipment shall be idle while
measurements are being made.
(3) In areas of working places specified in
§75.1719-1(e)(5) luminous intensity
measurements of the face, ribs, roof, floor, and exposed surfaces of mining
equipment, shall be made with the machine idle and located in the approximate
center of the working place with the drilling head toward the face and a
distance from the face of 5 feet, or the distance from the floor to the roof,
whichever is applicable. When the machine is located in the center of the
working place and the surfaces of the ribs to be illuminated are not within
the perimeter of the area determined in accordance with
§75.1719-1(e)(5), the machine shall be
positioned the applicable distance from the face and each rib and luminous
intensity measurements made for each rib, provided, however, that luminous
intensity measurements may be made of the face, roof, floor, and exposed
surfaces of mining equipment with the machine so located without locating the
machine in the center of the working place.
(4) In areas of working places specified in
§75.1719-1(e)(6), luminous intensity
measurements of a coal surface shall be made with the machine idle and
located in the approximate center of the working place with the appropriate
end toward the face and not less than 9 feet nor more than 10 feet from the
face.
(5) The area of surfaces to be measured shall be divided
into round or square fields having an area of not less than 3 nor more than 5
square feet as illustrated by the following figure:
(6) Measurements shall be taken with the photometer held
approximately perpendicular to the surface being measured and a sufficient
distance from the surface to allow the light sensing element in the
instrument to receive reflected light from a field of not less than 3 nor
more than 5 square feet. The luminous intensity of each such field shall be
not less than 0.06 footlambert.
(7) In areas of working places where clearances are
restricted to the extent that the photometer cannot be held a sufficient
distance from the surface to allow the light sensing element in the
instrument to receive reflected light from a field having an area of at least
3 square feet, luminous intensity shall be considered as the average of four
uniformly spaced readings taken at the corners and within a square field
having an area of approximately 4 square feet. In such instances, the area of
each of the individual readings shall not exceed 100 square inches. The
average of the four readings shall be not less than 0.06 footlambert. The
method of measurement is illustrated by the following figure:
DETERMINATION OF LUMINOUS INTENSITY BY AVERAGING METHOD
(8) Measurements shall not be made where shadows are cast
by roof control posts, ventilation equipment, or other obstructions necessary
to insure safe mining conditions.
(9) Where machine-mounted light fixtures are used on
equipment, except self advancing roof support systems, measurements shall not
be made of surfaces on or within 1 foot of a self-propelled machine.
(c) For the purpose of making illumination measurements, an
authorized representative of the Secretary may require the installation of
temporary roof supports or the removal of the equipment to a similar working
place in which permanent roof supports have been installed.
(d) Light measuring instruments shall be properly calibrated and
maintained. Instruments shall be calibrated against standards traceable to
the National Institute of Standards and Technology (Formerly the National
Bureau of Standards) and color corrected to the Commission
Internationale de l'Eclairage (CIE) Spectral Luminous Curve. The CIE Spectral
Luminous Curve is as follows:
