1374

LAWS OF MARYLAND

Ch. 418

(1)  The fan shall be powered with a permissible
driving unit and installed on the intake air side of the
entrance of the place to be ventilated not less than 16 feet
from the nearest rib;

(2)  The volume of air in which the fan is placed
shall be at least 2 and one-half times the manufacturer's
maximum rated capacity of the fan;

(3)  The fan and tubing shall be maintained in
good condition. The discharge end of the tubing shall be
kept within 35 feet of the face, and not more than 300 feet
of the tubing shall be extended from the fan;

(4)  A certified official or other competent
person designated by the mine foreman shall examine for
methane in places ventilated by means of a blower fan before
the fan is started at the beginning of the shift and after
the interruption of fan operation for five minutes or more
during the shift;

(5)  Accumulations of methane may not be moved by
a blower fan and tubing; only line brattice shall be used
for this purpose; and

(6)  The fan and tubing shall be inspected at
least twice during each working shift.

(d) (1) In General. The main intake air current shall
be divided into splits utilizing air crossings, where
needed, to ventilate effectively any part of the mine. The
number of workers on a split shall be limited to 75. The
quantity of air reaching the last open crosscut in any pair
or set of entries shall not be less than 6,000 cubic feet a
minute. However, the quantity of air reaching the last open
crosscut in any pair or set of entries in pillar sections
may be less than 6,000 cubic feet a minute, if at least
6,000 cubic feet of air a minute is being delivered to the
intake end of the pillar line. Mines operating without the
prescribed quantity of air in the last open crosscut of each
pair or set of entries, on July 1, 1973, may continue to
operate in this manner, but prompt action shall be taken to
deliver the required amount of air in the last open
crosscuts of each pair or set of entries in the mine.

(2)  Dilution of Smoke. The air current at every
working face shall have a sufficient volume and velocity to
dilute and carry away smoke from blasting and any flammable
or harmful gas.

(3)  Measurement. At least once each week, the
mine foreman, his assistants, or another competent person
designated by the mine foreman, shall measure the volume of
air near the main intake or main return, the amount passing
through the last open crosscuts of entries, and the volume
of air in each split. A record of these measurements shall