30 CFR § 33.4 Types of dust collectors for which certificates of approval may be granted.
(a) Certificates of approval will be granted only for completely
assembled dust-collector or combination units; parts or subassemblies will
not be approved.
(b) The following types of equipment may be approved: Dust-collector
or combination units having components designed specifically to prevent
dissemination of airborne dust generated by drilling into coal-mine rock
strata in concentrations in excess of those hereinafter stated in
§33.33 as allowable, and to confine or control the
collected dust in such manner that it may be removed or disposed of without
dissemination into the mine atmosphere in quantities that would create