(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. 2 (125 pounds per square inch gage).

(c) Where the pressure at any point in the supply system exceeds 863 kN/m. 2 (125 pounds per square inch gage), the respirator shall be equipped with a pressure-release mechanism that will prevent the pressure at the hose connection from exceeding 863 kN/m. 2 (125 pounds per square inch gage) under any conditions.