How to Perform a Method 9 Reading

Excerpt from Online Visible Emissions Course

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Getting ready to perform a VEO reading

Portion of VEO Form With Observations (partial)

EPA Method 9 observation form

Performing a VEO Reading

You have reviewed documentation, gathered equipment and performed the required field procedures. Now you are ready to read the visible emissions. This section will go through the steps taken to complete a VEO reading. Filling out the VEO form is an integral part of the process and will be covered in this section and in the next course section.

Double check your field conditions and correct any issues. Note: You may be required to postpone a reading if the conditions are not acceptable. Ensure that the procedure has your full attention. Do not text, talk on the phone, or perform other tasks while performing Method 9 observations.

The Process

  • Method 9 readings consist of observations at 15-second intervals over a period of six (6) minutes. Note: A reading consists of 24 observations. Method 9 requires 24 consecutive observations. You may be required to perform more than 24 observations to meet the 24 sequential observations requirement if you miss a reading or something else happens.
  • Observations are recorded to the nearest 5%.
  • The resulting 24 observations are averaged to determine the opacity value.
  • Method 9 prescribes that the observer shall not look continuously at the plume; observations are made by glancing at the plume at 15-second intervals.
  • Use the comments field to the right to document changes to the opacity or missed readings.

Recording the Observations and Determining the Opacity

A Simple Example
VEO observation form
A More Complex Example

As stated above, the Method requires 24 consecutive observations for a valid reading. You can choose 24 consecutive observations - they do not have to start on the minute interval:

An example of VEO observations