Method 7E
Determination of Nitrogen Oxides Emissions From Stationary Sources (Instrumental Analyzer Procedure)
40 CFR Part 60, Appendix A-4
From the method — regulatory text
Sections 1.0 and 2.0 of Method 7E—Determination of Nitrogen Oxides Emissions From Stationary Sources (Instrumental Analyzer Procedure), as published at 40 CFR Part 60, Appendix A-4. Retrieved 10/07/2026. The full method is on the eCFR.
1.0 Scope and Application
What is Method 7E?
Method 7E is a procedure for measuring nitrogen oxides (NOX) in stationary source emissions using a continuous instrumental analyzer. Quality assurance and quality control requirements are included to assure that you, the tester, collect data of known quality. You must document your adherence to these specific requirements for equipment, supplies, sample collection and analysis, calculations, and data analysis. This method does not completely describe all equipment, supplies, and sampling and analytical procedures you will need but refers to other methods for some of the details. Therefore, to obtain reliable results, you should also have a thorough knowledge of these additional test methods which are found in appendix A to this part:
(a) Method 1—Sample and Velocity Traverses for Stationary Sources.
(b) Method 4—Determination of Moisture Content in Stack Gases.
1.1 Analytes. What does this method determine? This method measures the concentration of nitrogen oxides as NO2.
| Analyte | CAS No. | Sensitivity |
|---|---|---|
| Nitric oxide (NO) | 10102-43-9 | Typically <2% of |
| Nitrogen dioxide (NO2) | 10102-44-0 | Calibration Span. |
1.2 Applicability. When is this method required? 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.
1.3 Data Quality Objectives (DQO). How good must my collected data be? 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 encountered. To meet this objective, the use of EPA traceability protocol calibration gases and measurement system performance tests are required.
1.4 Data Quality Assessment for Low Emitters. Is performance relief granted when testing low-emission units? Yes. For low-emitting sources, there are alternative performance specifications for analyzer calibration error, system bias, drift, and response time. Also, the alternative dynamic spiking procedure in section 16 may provide performance relief for certain low-emitting units.
2.0 Summary of Method
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.
EssentialRegs notes
Our plain-English reading of Method 7E. Not the method text.
What it measures
The concentration of nitrogen oxides (NOx), meaning nitric oxide plus nitrogen dioxide, in stack gas, measured continuously by an instrumental analyzer.
How it works
A sample of stack gas is drawn through a heated probe and a sample line to a conditioner that removes moisture, then to an analyzer that reads NOx continuously. Analyzers that respond to nitric oxide are paired with a converter that changes nitrogen dioxide into nitric oxide, and the converter's efficiency is tested. The method is built around quality checks: a calibration error test, a system bias check and a drift check, all run with calibration gases of known concentration.
Equipment
A chemiluminescence, ultraviolet, infrared or other NOx analyzer, with a heated sampling system, a moisture removal system, a data recorder and calibration gases certified to an EPA protocol.
When a rule cites it
Performance tests of engines, turbines, boilers, heaters and other combustion equipment against a NOx limit. It is also the method that supplies the NOx concentration when a rule expresses its limit in parts per million or needs it to calculate an emission rate.
Notes for compliance staff
Method 7E gives a concentration, so a limit stated in pounds per hour or per unit of heat input also needs a flow or fuel measurement. Rules that correct results to a stated oxygen level pair it with an oxygen reading, most often from Method 3A. Method 7E is a performance-based method: the tester shows through the calibration, bias and drift checks that the system measured correctly.
Cited by
Provisions in the corpus whose text cites Method 7E. Subscribers land on the provision in the regulation reader; visitors see a preview of it (the GP05 sample opens in full).
40 CFR Part 60 Subpart IIII
- Table 7 to Subpart IIII of Part 60 — Requirements for Performance Tests for Stationary CI ICE With a Displacement of ≥30 Liters per Cylinder
40 CFR Part 60 Subpart JJJJ
- Table 2 to Subpart JJJJ of Part 60 — Requirements for Performance Tests
The sections marked as regulatory text above are reproduced from the CFR. Everything under ‘EssentialRegs notes’ is our reference copy, not the method. The method as published in the CFR controls.