Ringelmann chart

Ringelmann chart

[′riŋ·gəl‚män ‚chärt]
(engineering)
A chart used in making subjective estimates of the amount of solid matter emitted by smoke stacks; the observer compares the grayness of the smoke with a series of shade diagrams formed by horizontal and vertical black lines on a white background.

Ringelmann chart

A chart used as the basis for evaluating the density of smoke discharged from chimneys.
References in periodicals archive ?
To facilitate enforcement, the Marine Department (MD) has been making reference to the Ringelmann Chart (see Annex) in assessing the level of dark smoke emission from vessels.
The MD has researched into overseas practice and noted that some ports in the United Kingdom and the United States have adopted a similar reference standard to the Ringelmann Chart as the benchmark for taking prosecution actions against excessive smoke emission from vessels.