Nationally Recognized Testing Laboratory (NRTL).
What requirements does OSHA have regarding NRTL’s?
OSHA standard, which are law, contain requirements for testing and certification by NRTL’s.
An explosion proof vacuum cleaner and dust collector must bear an NRTL certification. In this case it is Class II, Division 1, Group E.
This certification applies to the entire assembled piece of equipment and not only for the components.
The “Wet Mix” or also commonly called “Immersion Separator” uses liquids to neutralize, or render inert, metallic dusts. In this case Mineral Oil can be used for all commercial alloys with the exception of Zirconium.
To recover Zirconium dust, water is the only neutralizing agent that should be used.
On the other hand, water should not be used to neutralize aluminum. If water is the neutralizing agent used to recover aluminum dust then hydrogen gas can be generated. If this is the case then a device “valve” can be installed onto the piece of equipment to evacuate the hydrogen gas.
As per NFA 484, it is also suggested that NRTL certified equipment be used. In this case an explosion proof portable vacuum cleaner for the recovery of aluminum dust, or any other metallic dust, into a dry collection bag as long as the quantity to be recovered is less than 5 lbs.
The recovered metallic dust must be disposed of after a maximum 8 hr shift.
Following this type of procedure not only complies with the Authorities Having Jurisdiction (AHJ), but also with the workplace Canadian Center for Occupational Health & Safety (CCOHS) or Occupational Health & Safety Administration (OSHA)
Specialist in Hazloc Housekeeping and Recovery of Combustible/Conductive Dust and Flammable Liquids