Method 1
Sample and Velocity Traverses for Stationary Sources
40 CFR Part 60, Appendix A-1
From the method — regulatory text
Sections 1.0 and 2.0 of Method 1—Sample and Velocity Traverses for Stationary Sources, as published at 40 CFR Part 60, Appendix A-1. Retrieved 10/07/2026. The full method is on the eCFR.
1.0 Scope and Application
1.1 Measured Parameters. The purpose of the method is to provide guidance for the selection of sampling ports and traverse points at which sampling for air pollutants will be performed pursuant to regulations set forth in this part. Two procedures are presented: a simplified procedure, and an alternative procedure (see section 11.5). The magnitude of cyclonic flow of effluent gas in a stack or duct is the only parameter quantitatively measured in the simplified procedure.
1.2 Applicability. This method is applicable to gas streams flowing in ducts, stacks, and flues. This method cannot be used when: (1) the flow is cyclonic or swirling; or (2) a stack is smaller than 0.30 meter (12 in.) in diameter, or 0.071 m2 (113 in.2) in cross-sectional area. The simplified procedure cannot be used when the measurement site is less than two stack or duct diameters downstream or less than a half diameter upstream from a flow disturbance.
1.3 Data Quality Objectives. Adherence to the requirements of this method will enhance the quality of the data obtained from air pollutant sampling methods.
Note:
The requirements of this method must be considered before construction of a new facility from which emissions are to be measured; failure to do so may require subsequent alterations to the stack or deviation from the standard procedure. Cases involving variants are subject to approval by the Administrator.
2.0 Summary of Method
2.1 This method is designed to aid in the representative measurement of pollutant emissions and/or total volumetric flow rate from a stationary source. A measurement site where the effluent stream is flowing in a known direction is selected, and the cross-section of the stack is divided into a number of equal areas. Traverse points are then located within each of these equal areas.
EssentialRegs notes
Our plain-English reading of Method 1. Not the method text.
What it measures
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.
How it works
Gas does not move at the same speed or carry the same concentration everywhere in a stack, so one reading at one spot can mislead. Method 1 first sets the criteria for a suitable measurement site, based on how far it is from bends, fans, inlets and other flow disturbances. It then divides the cross-section into equal areas and fixes the traverse points, with the number of points depending on the stack dimensions and the distance from the nearest disturbances. The method also includes a check that the flow is not swirling in a cyclonic pattern.
Equipment
No analytical instrument. A tape measure or similar tool for stack dimensions, a pitot tube for the cyclonic flow check, and the sampling ports installed in the stack wall.
When a rule cites it
Performance tests of stacks and ducts, where the test plan has to show where the sample ports are and where each sampling or velocity point sits. It is invoked wherever a rule requires a velocity, flow rate or pollutant concentration determined across a stack cross-section.
Notes for compliance staff
Method 1 measures nothing itself. It is the first step that Methods 2, 4 and 5 and the other stack-sampling methods rely on for their points. A test site that cannot meet the distance-from-disturbance criteria is addressed by an alternative site-selection procedure within Method 1 itself. Stacks too small for Method 1 are covered by Method 1A.
Cited by
Provisions in the corpus whose text cites Method 1. Subscribers land on the provision in the regulation reader; visitors see a preview of it (the GP05 sample opens in full).
Regulation 6
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
40 CFR Part 60 Subpart OOOO
40 CFR Part 60 Subpart OOOOa
40 CFR Part 60 Subpart OOOOb
40 CFR Part 60 Subpart OOOOc
40 CFR Part 63 Subpart ZZZZ
- Appendix A to Subpart ZZZZ of Part 63 — Protocol for Using an Electrochemical Analyzer to Determine Oxygen and Carbon Monoxide Concentrations From Certain Engines
49 CFR Part 192
- § 192.9(f)(1)(i) — Method 1
- § 192.624(c)(1)
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.