VEO Form Instructions

Instructions	Forms (PDFs)
Company Identification Emission Description Emission Point Identification Process and Control Equipment	VEO Form - 30 minute VEO Form - 60 minute EPA VEO Form

Emission Description:

Includes Information that definitely establishes what was observed while making the visible determinations (observations). Note: Items called for in this section may change a number of times during the observation period. It is recommended that these changes be noted in the comment space beside the appropriate opacity readings (for each minute) and reference (letter a, b, c, etc. …..) to this be made in the corresponding space in this section.

Describe Emissions:

Include the physical characteristics and behavior of the plume (not addressed elsewhere on this form ) and the distance it is visible. Physical descriptions may include such things as texture, graduation, and contents; examples are "lacy", "fluffy" "copious". "mushrooming" (this would indicate poor engineering design on the fan selection), "puffing", "wisping" , "spreading over the horizon" and "detached non-water vapor condensibles." The Standard Plume Terminology illustrated on the bottom of page 46 may be used to describe plume behavior. The behavior is generally used to determine the atmospheric stability on the day of the opacity observations.

Emission Color:

Note the color of the emissions. The plume color can sometimes be useful in determining the composition of the emissions and also serves to document the total contrast between the plume and its background as seen by the opacity observer. For emissions that change color a number of times during the observation period (such as those from a basic oxygen furnace), the color changes should be noted in the comments space next to the opacity readings themselves.

Questions -

There are no emissions, but the subpart OOO source (limestone crusher and screening facility) has only a potential to emit emissions of a white or light gray emissions. What is the emission color? After emission color write -"Potential - White", at beginning and end put -"NONE".

The Emission color changes during the reading? Do I need to change locations/backgrounds? How do I document this? You do not necessarily need to change position but you can. Use a superscript a to denote a footnote or reference to a comment, this may include that the emission color changed so you stopped reading at a certain time and resumed reading at a specific time or may simply denote the color change and now the lack of contrast may under-report the actual opacity, allowing a continual reading without change of location.

I cannot get a contrasting background - can I still read? Yes. Documenting the color and the background will pour meaning into your readings by clearly delineating the degree of contrast or lack thereof.

If Water Droplets Plume: This box is only completed if visible water droplets are present (see Water Vapor Plume Video). Check "attached" if condensation of the moisture contained in the plume occurs within the stack and the water droplet plume is visible at the stack exit. Check "detached" if condensation occurs some distance downwind of the stack exit and the water droplet plume and the stack appear to be unconnected.

Plumes containing condensed water vapor ("water droplet plumes" or "steam Plumes") are usually very white and billowy (like white clouds) and then wispy at the point of dissipation, where the opacity decreases from a high value (usually 100%) to zero if there is no residual opacity contributed by contaminate in the plume. Water Vapor collapses upon itself as it evaporates back in the atmosphere, more quickly in low humidity conditions.

To document the presence or absence of condensed water vapor in the plume two points must be addressed.

First - Is sufficient moisture present (condensed or uncondensed) in the effluent to produce water droplets at in-stack or ambient conditions?

Second - If enough moisture is present, are the in-stack or ambient conditions such that it will condense either before exiting the stack or after exiting (when it meets ambient air)?

The First Question can be answered by examining the process type and/or the treatment of the effluent gas after the process. Some common sources of moisture in plumes are:

Water produced by combustion of fuels

Water from dryers

Water introduced by wet scrubbers

Water Introduced for gas cooling prior to an electrostatic precipitator or other control device

Water used to control the temperature of chemical reactions (cooling water)

If water is present in the plume, data from a sling psychrometer, which can be used to determine the relative humidity, in combination with the moisture content and temperature of the effluent gas can be used to predict whether the formation of a steam plume is probable .

Prior Source Test data can be used for the determination of the process effluent condition (Moisture and Temperature) and the referenced relative humidity from the nearest airport (weather.com or other site) can be used to make the ambient condition determination.

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