EPA Method 7E is a procedure for measuring nitrogen oxides (NOx) in stationary source emissions using a continuous instrumental analyzer. The use of Method 7E may be required by specific New Source Performance Standards, Clean Air Marketing rules, State Implementation Plans, and permits where measurement of NOx concentrations in stationary source emissions is required, either to determine compliance with an applicable emissions standard or to conduct performance testing of a continuous monitoring system (CEMS). Other regulations may also require the use of Method 7E. Method 7E is designed to provide high-quality data for determining compliance with Federal and State emission standards and for relative accuracy testing of CEMS. In these and other applications, the principal objective is to ensure the accuracy of the data at the actual emission levels Method 7E 5/21/2018 encountered. To meet this objective, the use of EPA traceability protocol calibration gases and measurement system performance tests are required.
In this method, a sample of the effluent gas is continuously sampled and conveyed to the analyzer for measuring the concentration of NOx. You may measure NO and NO2 separately or simultaneously together but, for the purposes of this method, NOx is the sum of NO and NO2. You must meet the performance requirements of this method to validate your data.