| 摘要 |
Breathing responsive powered air purifying respirator apparatus comprising an air-tight housing having connections for filters (5) and for supply of purified air to a face mask (3), a motor-driven blower arranged inside said air-tight housing for drawing air through said filter units and for the supply of purified air to the face mask. The blower is a lobe blower (6) delivering a constant flow of air. A regulator (10) is arranged in said housing in parallel with the lobe blower (6), and a by-pass conduit (11) connects the outlet side (12) of the lobe blower to the inlet side (13) of the lobe blower, wherein said regulator is arranged to open said by-pass conduit, when a pressure in the face mask exceeds a predetermined positive pressure.
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