42 C.F.R. § 84.148
Type C supplied-air respirator, continuous flow class; minimum requirements
(a) Respirators tested under this section shall be approved only when they supply respirable air at the pressures and quantities required.
(b) The pressure at the inlet of the hose connection shall not exceed 863 kN/m.
(c) Where the pressure at any point in the supply system exceeds 863 kN/m.