Rule 6.
(1) It
is the dual function of grinding and abrasive cutting-off wheel hoods to
protect the operator from the hazards of bursting wheels and to provide a means
for the removal of dust and dirt generated. All hoods shall be not less in
structural strength than specified in the American National Standard Safety
Code for the Use, Care, and Protection of Abrasive Wheels, B7.1-1970. ANSI
B7.1-1970 is adopted by reference in this rule. Printed copies of ANSI
B7.1-1970 are available from Global Engineering Documents, 15 Inverness Way
East, Englewood, Colorado 80112, telephone number 1-800-854-7179, website:
www.global.ihs.com [File Link Not Available], at a cost as of the time of
adoption of these rules of $45.00 or is available for inspection at the
Michigan Department of Consumer and Industry Services, Standards Division, 7150
Harris Drive, P.O. Box 30643, Lansing, Michigan 48909.
(2) Due to the variety of work and types of
grinding machines employed, hoods shall adapt to the particular machine in
question, and such hoods shall be located as close as possible to the
operation.
(3) Exhaust hoods for
floor stands, pedestals, and bench grinders shall be designed in accordance
with Figure G-2. The adjustable tongue shown in the figure shall be kept in
working order and shall be adjusted within one-fourth inch of the wheel
periphery at all times.
(4)
Swing-frame grinders shall be provided with exhaust booths as indicated in
Figure G-3.
(5) Portable grinding
operations, whenever the nature of the work permits, shall be conducted within
a partial enclosure. The opening in the enclosure shall not be larger than is
actually required in the operation and an average face air velocity of not less
than 200 feet per minute shall be maintained.
(6) Hoods for polishing and buffing and
scratch-brush wheels shall be constructed to conform as closely to Figure G-4
as the nature of the work will permit.
(7) Cradle grinding and polishing operations
shall be performed with a partial enclosure similar to Figure G-5. The operator
shall be positioned outside the working face of the opening of the enclosure.
The face opening of the enclosure should not be greater in area than that
required for the performance of the operation, and the average air velocity
into the working face of the enclosure shall not be less than 150 feet per
minute.
(8) Hoods for horizontal
single-spindle disc grinders shall be constructed to conform as closely as
possible to the hood shown in Figure G-6. There shall be a space between the
back of the wheel and the hood, and a space around the periphery of the wheel
of at least 1 inch to permit the suction to act around the wheel periphery. The
opening on the side of the disc shall not be larger than is required for the
grinding operation, but shall not be less than twice the area of the branch
outlet.
(9) Horizontal
double-spindle disc grinders shall have a hood encircling the wheels and
grinding chamber similar to that illustrated in Figure G-7. The openings for
passing the work into the grinding chamber should be kept as small as possible,
but shall not be less than twice the area of the branch outlets.
(10) Vertical-spindle disc grinders shall be
encircled with a hood constructed so that the heavy dust is drawn off a surface
of the disc and the lighter dust exhausted through a continuous slot at the top
of the hood as shown in Figure G-1.
(11) Grinding and polishing belt hoods shall
be constructed as close to the operation as possible. The hood should extend
almost to the belt, and 1-inch openings should be provided on either side.
Figure G-8 shows a typical hood for a belt operation. R. 325.52506 Tables and
Charts
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Figure G-1
Vertical Splndla Disc Grinder Exhaust Hood and
Branch Pipe Connections
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Figure G-2
Standard Grinder Hood
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Figure G-3
A Method of Applying an Exhaust Encloser Swing-frame
Grinders
Note: Baffle to reduce front opening as much as
possible.
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Figure G-4
Standard Buffing and polishing Hood
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Figure G-5
Cradle Polishing or Grinding
Enclosure
Entry loss " 0.44 velocity pressure for tapered
takeoff.
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Figure G-6
Horizontal Single-Spindle Disc Grinder Exhaust
flood and Branch Pipe Connections
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Figure G-7
Rorlsontal Double-Splndle Disc Grinder Exhaust Hood
and Branch Pipe Connections
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Figure G-8
A Typical Hood for a belt Oparation
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