Standard Interpretations - Table of Contents
• Standard Number: 1910.134(d)(1)(ii); 1910.156(f)(1)(iv); 1910.120(q)(3)(x)

OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at

June 20, 1997


FROM: JOHN B. MILES, JR., Director
[Directorate of Enforcement Programs]

SUBJECT: SCBA Cylinder Interchangeability

Recently it has come to our attention that some manufacturers are promoting their lower priced cylinders for use on other manufacturer's self-contained breathing apparatuses (SCBAs). They are also telling their customers that this practice is allowed by OSHA standards. This statement is misleading. Employers who use components from other manufacturers on respirator equipment are voiding the NIOSH approval for their respirators.

Two of OSHA's standards [1910.156(f)(1)(iv) and 1910.120(q)(3)(x)] do permit the use of other manufacturer's cylinders on self-contained breathing apparatuses (SCBA's), when deemed necessary to meet the tasks at hand. OSHA's concession to this practice is only intended to