__________________________________________________Chapter 2 - Principle of Operation, Page 2-5
Grease Extraction/Smoke Removal – Cont.
Basic Facts About Smoke
Smoke particles are extremely small and not visible to the human eye unless thousands of them are
grouped together to form what we see as smoke. Individual particles are measured in units called
microns and one micron equals 1/25,400 of an inch (1/64,516 of a cm).
Smoke generated by commercial cooking equipment has a particulate size of 0.15 microns and it is
these very small particles that smoke abatement equipment must remove from the airstream. The
amount of smoke being discharged from a kitchen exhaust duct is measured in terms of its density,
referred to as opacity - the degree to which emissions block light. A 100% opacity level would be solid
black and 0% would be perfectly clear. Control agencies that have adopted smoke pollution ordinances
are requiring an opacity level of no more than 20%, which is a very light blue smoke.
Typically, heavy smoke producing cooking such as charbroiling creates an opacity level of 60% to 70%.
Opacity readings are taken by the human eye by viewing the smoke being discharged and then
assigning a percentage of opacity to what is seen. Though this method is quite subjective, it is the
method practiced by control agency inspectors who are trained and certified in determining opacity
percentages
Other more technical methods of determining opacity or particulate density are achieved through the
use of opacity meters and cascade impactors. This level of analysis is usually referred to as source
testing. Control agencies occasionally require this type of analysis and if so, the testing is conducted by
state certified contractors which can be quite costly and time-consuming. The efficiency of a pollution
control unit is based on how well it reduces the opacity level of a given airstream. The Gaylord ClearAir
unit will reduce the opacity level below 20%, thereby meeting the requirements of environmental control
agencies.
Figure 2-5-1
Electrostatic Cell
Side View
Figure 2-5-2
Electrostatic Cell
Isometric View
