More methods
40 CFR Part 60 Appendix A, Part 51 Appendix M, and Part 63 Appendix A
Methods 1 through 5 are the skeleton. Most other methods keep that skeleton and swap what sits behind the filter: different impinger solutions, sorbent traps, or analyzers for one pollutant family.
- Answers
- Which method measures this pollutant, and how is its train different from Method 5?
- Where they live
- Part 60 Appendix A (NSPS methods), Part 51 Appendix M (201A, 202), Part 63 Appendix A (300 series)
- Common thread
- Most reuse Method 1 points, Method 2 flow, Method 3 gas composition and Method 4 moisture
- Choose by
- What the rule or permit cites. The regulation names the method; you rarely get to pick.
Method finder
Filter by pollutant family or search by method number, pollutant, or technique. Each card notes which of the core methods it builds on.
Same skeleton, different back half
Put the trains side by side and the pattern is obvious. The nozzle, heated probe and heated filter rarely change, because they come from Method 5 and keep the isokinetic sample representative. What changes is everything after the filter, and which pieces go to the lab.
Sampling trains compared
Switch trains and compare what is analyzed.
Solution strengths and impinger counts follow the current method text; check it and your protocol before you charge a train.
Reading opacity: Method 9
Method 9 has no sampling train at all. A certified observer stands where they can see the plume clearly and records its opacity, the percent of background light it blocks, to the nearest 5% every 15 seconds. Twenty-four consecutive readings make one 6-minute average, which is usually what an opacity limit is written against.
Where the observer stands matters as much as their eyes. The sun must be in the 140° sector behind them, so glare does not wash out the plume, and they should look across the plume rather than along it. Readings are taken where the plume is densest but past any condensed water vapor, which is steam and not a pollutant.
Where to stand
Move the observer and the sun. The shaded wedge is the 140° sector behind the observer.
The wind blows the plume toward the east in this view. Directions are compass bearings.
Method 9 essentials
- Observer certified at a smoke school, and recertified every 6 months.
- Readings to the nearest 5% opacity at 15-second intervals.
- Twenty-four consecutive readings form a 6-minute average.
- Sun in the 140° sector behind the observer; line of sight roughly perpendicular to the plume.
- Read at the densest part of the plume where no condensed water vapor is present.
Field mistakes that cost runs
Running the method you know, not the method the rule cites
A permit that cites Method 5B will not accept a Method 5 result, and a PM2.5 limit may need Method 201A and 202 together. Read the citation before you pack the truck.
Contaminating trace-level trains
Metals, mercury, and dioxin trains measure micrograms or less. Ungloved hands, unwashed glassware, or a reagent lot without a blank can swamp the sample.
Letting acid gases condense
HCl dissolves in any liquid water it meets. A cold spot ahead of the impingers, or a filter that drops below temperature, strips it out of the gas where nothing will analyze it.