(7) "Exhaust system" means a system consisting of branch pipes connected to hoods
or enclosures, 1 or more header pipes, an exhaust fan, means for separating solid
contaminants from the air flowing in the system, and a discharge stack to outside.
(8) "Grinding wheels" means all power-driven rotatable grinding or abrasive
wheels, except disc wheels as defined in this standard, consisting of abrasive
particles held together by artificial or natural bonds and used for peripheral grinding.
(9) "Header pipe (main pipe)" means a pipe into which 1 or more branch pipes
enter and which connects such branch pipes to the remainder of the exhaust system.
(10) "Hoods and enclosures" means the partial or complete enclosure around the
wheel or disc through which air enters an exhaust system during operation.
(11) "Horizontal double-spindle disc grinder" means a grinding machine
carrying 2 power-driven, rotatable, coaxial, horizontal spindles upon the inside ends of
which are mounted abrasive disc wheels used for grinding 2 surfaces simultaneously.
(12) "Horizontal single-spindle disc grinder" means a grinding machine carrying
an abrasive disc wheel upon 1 or both ends of a power-driven, rotatable single
(13) "Polishing and buffing wheels" means all power-driven rotatable wheels
composed all or in part of textile fabrics, wood, felt, leather, paper, and may be coated
with abrasives on the periphery of the wheel for purposes of polishing, buffing, and
(14) "Portable grinder" means any power-driven rotatable grinding, polishing,
or buffing wheel mounted in such manner that it may be manually manipulated.
(15) "Scratch-brush wheels" means all power-driven rotatable wheels made from
wire or bristles and used for scratch cleaning and brushing purposes.
(16) "Swing-frame grinder" means any power-driven rotatable grinding,
polishing, or buffing wheel mounted in such a manner that the wheel with its supporting
framework can be manipulated over stationary objects.
(17) "Velocity pressure (vp)" means the kinetic pressure in the direction of flow
necessary to cause a fluid at rest to flow at a given velocity. It is generally expressed in
inches of water gauge.
(18) "Vertical-spindle disc grinder" means a grinding machine having a vertical,
rotatable power-driven spindle carrying a horizontal abrasive disc wheel.
History: 2003 AACS.
R 325.52503 Application.
Rule 3. (1) An employer shall provide suitable hood or enclosures that are
connected to exhaust systems for every establishment performing dry grinding, dry
polishing, or buffing.
(2) Exhaust systems shall be operated continuously whenever operations are
carried on, and shall be capable of preventing contaminants from entering the breathing
zone of employees.
History: 2003 AACS.