Health - Diet and Nutrition Quiz No. 2 Progress Indicator: Question 3 of 10 3.  The required minimum number and type of gas detectors that must be provided at a mine rescue station is? Choices: 2 equipped with CO, CO2, O2 and LEL 4 equipped with CO, NO2, O2 and LEL 4 electronic detectors or 4 Dräger pumps equipped for detecting CO, NO, O2 and Methane None of the above