An oxygen analyzer will typically be equipped with a hand pump. This hand pump is very long and narrow. People will need to squeeze that hand pump in order to test it. One end of the hand pump will blow out the air and one end will not.
The end of the hand pump that actually blows out the air is the one that needs to be connected tightly to the inlet port of the oxygen analyzer. Once people have completed this test, the oxygen analyzer itself should be close to ready for anything else that people will need.