What are the basic fundamentals of reading opacity in the field at my plant?

Whitlow Smoke School Nation

Before we start the smoke school certification test, we always have a mini-lecture (download mini-lecture) to explain the basic fundamentals of passing the certification test and how to read opacity in the field. The bible for EPA Method 9 visible emissions opacity evaluations is 40 CFR 60 Appendix A. In order to correctly evaluate opacity you must follow these guidelines, otherwise you will make significant errors in your evaluation. This is critical if you are a state or federal inspector. Your inspection may result in notices of violations for problems that do not exist. This error would cause all sorts of problems for the industrial plant you are inspecting. The company may challenge your inspections and report the error to your supervisor. The company may challenge your inspection in court. What size suit do you wear? I hate being in court. These challenges would result in significant embarrassment to you and to your department. This court case resulted in an embarrassment to the inspector and his agency.

Representatives from industrial plants or other non-regulating agencies should use the correct fundamentals when reading opacity. Your job is to document compliance with your permit and all regulations relating to air quality. Your mistakes could cost your company embarrassment when you receive notices of violations, fines, court appearances, and negative publicity. This court case resulted in several plant staff being fired.

The opacity evaluator should follow basic fundamentals. Before we start the smoke school certification test, we always have a mini-lecture to teach the basic fundamentals of how to take the smoke school test and how to read opacity in the field. We start out with these fundamentals of how to read opacity in the field at your plant:

1. How to choose an observation position- where to stand

Sun to your back
Winds blowing perpendicular to your line of view- from your left to your right- not coming at you or going away from you
Get back at least 3 stack heights to obtain a vertical angle of 18 degrees or less
How to make and use a Boudreaux Level to determine your vertical angle
Choose an observation position that allows a contrasting background. You can not read white smoke with white clouds in the background. You can not read black smoke with black clouds in the background.
How to use a Ringelmann smoke chart for black smoke

2. How to choose the correct observation point- where to look at and observe the plume

The densest part of the plume
No steam- at the tip of the smokestack before the plume spreads
Attached steam- touching the smokestack- observe at the end of the steam plume- the densest part of the plume after the steam ends or evaporates
Detached steam- not touching the smokestack- read before the steam starts or after the steam ends

Recording Observations. Opacity observations shall be recorded to
the nearest 5 percent at 15-second intervals on an observational record
sheet. (See Figure 9-2 for an example.) A minimum of 24 observations
shall be recorded. Each momentary observation recorded shall be deemed
to represent the average opacity of emissions for a 15-second period.

Data Reduction. Opacity shall be determined as an average of 24
consecutive observations recorded at 15-second intervals. Divide the
observations recorded on the record sheet into sets of 24 consecutive
observations. A set is composed of any 24 consecutive observations.
Sets need not be consecutive in time and in no case shall two sets
overlap. For each set of 24 observations, calculate the average by
summing the opacity of the 24 observations and dividing this sum by 24.
If an applicable standard specifies an averaging time requiring more
than 24 observations, calculate the average for all observations made
during the specified time period. Record the average opacity on a
record sheet.