Problem: we are not achieving more than 81% of oxygen concentration at the patient.

Test setup: The Fluke gas flow analyser is placed in different parts of the air/oxygen circuit to isolate the suspected leak.


Machine 1Machine 2Machine 3Machine 4
F102 = oxygen sensor91 %90 %82 %82 %
Between lung and oxygen sensor (fluke)97 %98.790 %94.3 %
Between oxygen sensor and bellow97.5 %99.1 %91 %94.8 %
Between bellow en distribution block98 %99.7 %98 %99.5 %


  • machine 3 and 4 had bellows assembled without seals and were leaking
  • several oxygen sensors were also leaking and were fixed
  • after fixes, oxygen sensors still measure 7% lower than the Fluke. This was fixed in firmware
  • the oxygen test is a valid test to see if there is leakage in both bellow and/or oxygen sensor