| abstract |
The invention is directed to an oxygen sensor arrangement 8 for sensing the oxygen in a breathing loop 29 of a breathing apparatus 100 . The sensor arrangement 8 comprises at least one primary oxygen sensor 30 arranged to operatively measure the oxygen in the breathing loop 29 , and a control arrangement 40 for obtaining measures from said oxygen sensor. A test channel arrangement 15, 362 is adapted to operatively provide a first gas having a first fraction of oxygen from a first supply 20 to said primary oxygen sensor 30 at a position 267 adjacent to or directly adjacent to said primary oxygen sensor. A first test valve arrangement 41 is arranged to operatively open and close the flow of said first gas through said test channel arrangement 15, 362 . Said a control arrangement 40 is arranged to operatively actuate said first test valve arrangement 41 so as to provide an amount of said first gas to said primary oxygen sensor 30 via said test channel arrangement 15, 362. |