Greisinger gmh3691 and ggo369 residual oxygen measuring device with sensor greisinger gmh3691 ggo369 p the greisinger gmh3691 is a residual oxygen measuring device and ggo369 is a standard sensor for use with applications without larger concentrations of co sup2 p p the greisinger gmh 3691 measures the oxygen partial pressure and the oxygen concentration in gas mixtures and air for the measurement an external sensor of the type goo or ggo is required the measurement takes place