15.2.2.4 Bulk Accumulations.
15.2.2.4.1 Spills shall be removed at once, using conductive scoops and soft bristle brushes that have natural fiber bristles.
Scoops shall be nonsparking unless otherwise authorized for the specific application.
15.2.2.4.2 Vacuum Cleaning.
15.2.2.4.2.1 Vacuum cleaning systems shall be used only for removal of dust accumulations too small, too dispersed, or too inaccessible to be thoroughly removed by hand brushing.
15.2.2.4.2.2 Vacuum cleaning systems shall be effectively bonded and grounded to minimize the accumulation of static electric charge.
15.2.2.4.2.3 * Because of the inherent hazards associated with the use of vacuum cleaning systems and portable vacuum systems for finely divided combustible metal dusts, special engineering analysis shall be given to the design, installation, maintenance, and use of such systems.
15.2.2.4.2.4 Portable vacuum cleaners shall be used only if rated or approved for use with combustible metals dust.
(A) They shall be permitted only for small amounts of re- sidual material remaining after preliminary cleanup.
(B) They shall be emptied at the end of each operational period or shift.
(C) They shall not be used as primary dust collectors.
15.2.2.4.2.5 Vacuum cleaner hose, nozzles, and fittings shall be made of conductive nonsparking material.
15.2.2.4.2.6 Assembled components shall be conductive and bonded where necessary.
15.2.2.4.2.7 Periodic test for continuity shall be performed.
15.2.2.4.2.8 Combustible metal dust picked up by a fixed vacuum cleaning system shall be discharged into a container or collector location outside the building.
15.2.2.4.3 Compressed-Air Cleaning Requirements. 15.2.2.4.3.1 Compressed-air blowdown shall not be permit-
ted, unless the conditions of 15.2.2.4.3.2 are met.
15.2.2.4.3.2 In certain areas that are otherwise impossible to clean, compressed-air blowdown shall be permitted under con- trolled conditions with all potential ignition sources prohibited in or near the area and with all equipment shut down