The OSHA National Emphasis Program for Combustible Dusts, initially released in October 2007 and reissued for emphasis and increased enforcement in March 2008, has generated many inquiries about suitability of industrial vacuum cleaning systems for use in Class II, Div 2 environments.
One option is air-powered vacuums, which do not use electricity and do not generate any heat from operation. For example, Vac-U-Max Models 40008, 40012, and 40013 compressed air-powered vacuums meet NFPA 77 requirements for grounding and bonding via bumper-to-bumper grounded and bonded design.
Specific static control components of this family of vacuums are metal vacuum cleaning tools and static-dissipative vacuum hose, stainless steel antisparking inlet, static-conductive dust filters, ground strap across gasket between air vacuum cover and drum, drum dolly with static-conductive casters, ground wire connection between air vac cover and drum dolly, static-conductive compressed air hose with metal quick-disconnect fittings, and static-conductive polybag liners for collection of combustible dusts inside the drum.
If the facility’s compressed air piping network is grounded (as it should be), the Vac-U-Max vacuum will be grounded automatically, eliminating operator error due to failure to connect separate ground wires.
The vacuums meet the definition of an intrinsically safe system, comprised of vacuum cover, drum, dolly, vacuum hose, and cleaning tools, compressed air hose with quick-disconnect fittings, and polybag drum liners. Because there are no customer-supplied components, the manufacturer can offer a suitable-for-service certification in a Class II, Div 2 environment.