Abstract: A closed cycle respirator is disclosed which includes a respiration air cycle having a breathing bag and a carbon dioxide absorber with connecting lines between the breathing bag and absorber and to a junction adapted for use by the user of the equipment. A pressurized oxygen bottle is provided with a controllable valve for supplying oxygen to the cycle in case the oxygen drops below a selected value in the breathing bag. In case of failure of the controllable valve, a separate oxygen supply connection is provided to the breathing cycle with a valve which senses a reduction of pressure in the breathing cycle and opens the connection to the oxygen bottle for emergency supply of oxygen to the cycle.

Abstract: A closed cycle respirator with emergency oxygen supply is disclosed which comprises a main oxygen flow path from an oxygen bottle into a breathing bag of the closed breathing cycle. A switching valve is provided in the first path and branches off into a second path also for supplying oxygen into the bag. The first oxygen flow path has a solenoid valve therein which is controlled by a first oxygen sensor in the breathing bag. The switching valve is controlled by a second oxygen sensor in the breathing bag for switching oxygen supply over to the second flow path in case the solenoid valve malfunctions or anytime the oxygen in the bag falls below or rises above a set desired limit.