42 CFR §84.71

1. (a)Each self-contained breathing apparatus described in § 84.70 shall, where its design requires, contain the following component parts:
   1. (1)Facepiece or mouthpiece, and noseclip;
   2. (2)Respirable breathing gas container;
   3. (3)Supply of respirable breathing gas;
   4. (4)Gas pressure or liquid level gages;
   5. (5)Timer;
   6. (6)Remaining service life indicator or warning device;
   7. (7)Hand-operated valves;
   8. (8)Breathing bag;
   9. (9)Safety relief valve or safety relief system; and
   10. (10)Harness.
2. (b)The components of each self-contained breathing apparatus shall meet the minimum construction requirements set forth in subpart G of this part.