Section 84.51 - Entry and escape, or escape only; classification
Respirators described in subparts H through L of this part shall be classified for use as follows:
(a)Entry and escape. Respirators designed and approved for use during entry into a hazardous atmosphere, and for escape from a hazardous atmosphere; or(b)Escape only. Respirators designed and approved for use only during escape from a hazardous atmosphere.