84.72—Breathing tubes; minimum requirements.
Flexible breathing tubes used in conjunction with breathing apparatus shall be designed and constructed to prevent:
(a)
Restriction of free head movement;
(b)
Disturbance of the fit of facepieces and mouthpieces;
(c)
Interference with the wearer's activities; and
(d)
Shutoff of airflow due to kinking, or from chin or arm pressure.