Test Methods
Reference pages for the EPA test methods the regulations on this site cite. Each page opens with the method’s own Scope and Summary sections, reproduced from the CFR, followed by EssentialRegs notes and the provisions that cite it. The full text of each method is on the eCFR.
Stack sampling fundamentals
Method 1 — Sample and Velocity Traverses for Stationary Sources
Where in a stack or duct to sample, and at how many points across its cross-section, so that a gas sample or velocity measurement represents the whole flowing gas stream.
Method 1A — Sample and Velocity Traverses for Stationary Sources With Small Stacks or Ducts
Where to sample, and at how many points across the cross-section, in stacks and ducts that are too small for the Method 1 procedure.
Method 2 — Determination of Stack Gas Velocity and Volumetric Flow Rate (Type S Pitot Tube)
The average velocity of the gas in a stack or duct and the volumetric flow rate of that gas, both at stack conditions and corrected to standard conditions.
Method 2A — Direct Measurement of Gas Volume Through Pipes and Small Ducts
The total volume of gas that passes through a pipe or small duct over a test period, and from it the flow rate, corrected to standard conditions.
Method 2D — Measurement of Gas Volume Flow Rates in Small Pipes and Ducts
The volumetric flow rate of gas in a small pipe or duct, measured with a flow meter installed in the line or at its outlet and corrected to standard conditions.
Method 4 — Determination of Moisture Content in Stack Gases
The moisture content of a stack gas, as the percent of the gas by volume that is water vapor.
Gas composition and molecular weight
Method 3 — Gas Analysis for the Determination of Dry Molecular Weight
The carbon dioxide and oxygen content of a stack gas, and from them the dry molecular weight of the gas.
Method 3A — Determination of Oxygen and Carbon Dioxide Concentrations in Emissions From Stationary Sources (Instrumental Analyzer Procedure)
The concentration of oxygen, carbon dioxide, or both, in a stack gas, read continuously by an instrumental analyzer.
Method 3B — Gas Analysis for the Determination of Emission Rate Correction Factor or Excess Air
The oxygen, carbon dioxide and carbon monoxide content of a stack gas, and from them an emission rate correction factor or the percent excess air.
Method 3C — Determination of Carbon Dioxide, Methane, Nitrogen, and Oxygen From Stationary Sources
The concentrations of carbon dioxide, methane, nitrogen and oxygen in a gas sample.
Method 10 — Determination of Carbon Monoxide Emissions From Stationary Sources (Instrumental Analyzer Procedure)
The concentration of carbon monoxide (CO) in stack gas, measured continuously by an instrumental analyzer.
Method 19 — Determination of Sulfur Dioxide Removal Efficiency and Particulate Matter, Sulfur Dioxide, and Nitrogen Oxide Emission Rates
Emission rates of sulfur dioxide, nitrogen oxides and particulate matter, expressed per unit of heat input, and the sulfur dioxide removal efficiency of a control system or fuel treatment.
Method 320 — Measurement of Vapor Phase Organic and Inorganic Emissions by Extractive Fourier Transform Infrared (FTIR) Spectroscopy
The concentration of many gaseous organic and inorganic compounds in a stack or duct gas, measured at the same time by extractive Fourier transform infrared (FTIR) spectroscopy.
Particulate matter
Opacity and visible emissions
Method 9 — Visual Determination of the Opacity of Emissions From Stationary Sources
The opacity of a visible emission plume — the degree to which it obscures the view behind it — expressed as a percentage, as judged by a trained and certified observer.
Method 22 — Visual Determination of Fugitive Emissions From Material Sources and Smoke Emissions From Flares
Whether visible emissions are present from a source such as a fugitive material source or a flare, and the total time they are visible during an observation period.
Leaks and fugitive emissions
Method 21 — Determination of Volatile Organic Compound Leaks
Whether a piece of equipment — a valve, pump seal, flange, connector, open-ended line or similar component — is leaking volatile organic compounds, by reading the concentration at the component's surface against a leak definition set by the rule.
Method 27 — Determination of Vapor Tightness of Gasoline Delivery Tank Using Pressure Vacuum Test
Whether a gasoline cargo tank, such as a tank truck compartment, holds pressure and vacuum, shown by how much the internal pressure changes over a fixed time.
Organic compounds
Method 18 — Measurement of Gaseous Organic Compound Emissions By Gas Chromatography
The concentrations of individual gaseous organic compounds in an exhaust gas or process stream, identified and measured by gas chromatography.
Method 24 — Determination of Volatile Matter Content, Water Content, Density, Volume Solids, and Weight Solids of Surface Coatings
The volatile organic compound (VOC) content of a surface coating, together with the coating's water content, density, volume solids and weight solids.
Method 25A — Determination of Total Gaseous Organic Concentration Using a Flame Ionization Analyzer
The total concentration of gaseous organic compounds in a gas stream, measured continuously as total hydrocarbons.
Sulfur and nitrogen compounds
Method 6 — Determination of Sulfur Dioxide Emissions From Stationary Sources
The concentration of sulfur dioxide (SO2) in stack gas, determined from gas collected in a wet-chemistry sampling train.
Method 7E — Determination of Nitrogen Oxides Emissions From Stationary Sources (Instrumental Analyzer Procedure)
The concentration of nitrogen oxides (NOx), meaning nitric oxide plus nitrogen dioxide, in stack gas, measured continuously by an instrumental analyzer.
Method 15 — Determination of Hydrogen Sulfide, Carbonyl Sulfide, and Carbon Disulfide Emissions From Stationary Sources
The concentrations of hydrogen sulfide, carbonyl sulfide and carbon disulfide in an exhaust gas, each determined separately.
Method 16 — Semicontinuous Determination of Sulfur Emissions From Stationary Sources
The concentrations of individual reduced sulfur compounds in an exhaust gas, including hydrogen sulfide, methyl mercaptan, dimethyl sulfide and dimethyl disulfide, measured at repeated intervals.
Method 16A — Determination of Total Reduced Sulfur Emissions From Stationary Sources (Impinger Technique)
The combined concentration of total reduced sulfur (TRS) compounds in an exhaust gas, reported as a single total.
Continuous emission monitoring systems
Performance Specification 2 — Specifications and Test Procedures for SO2 and NOX Continuous Emission Monitoring Systems in Stationary Sources
Whether a continuous emission monitoring system for sulfur dioxide, nitrogen oxides or both is acceptable for use, based on its installation, performance and accuracy.
Performance Specification 8 — Performance Specifications for Volatile Organic Compound Continuous Emission Monitoring Systems in Stationary Sources
Whether a continuous emission monitoring system for volatile organic compounds is acceptable for use, based on its installation, performance and accuracy.
Performance Specification 9 — Specifications and Test Procedures for Gas Chromatographic Continuous Emission Monitoring Systems in Stationary Sources
Whether a continuous emission monitoring system that uses a gas chromatograph is acceptable for measuring specific gaseous compounds, based on its installation, performance and accuracy.
Method validation
Methods not listed here (NIOSH, CARB, ASTM and other EPA methods the corpus cites only in passing) are left as plain text in the regulations.