| Interference gas | Concentration | Applicable analyzer | 
|---|---|---|
| CO2 | 14 percent | CO | 
| C3H8 | 1 percent | CO | 
| 
                     
                                
                                    Code of Federal Regulations
                                
                                261
                             
                         | 
            ||
| H2O | Saturated vapor at 100 °F | CO | 
| NOX | 1,000 ppm | CO | 
| O2 | 5 percent | CO |