BS 2742:2009 Use of the Ringelmann and miniature smoke charts
Smoke emission can be assessed using Ringlemann and miniature smoke charts. These charts compare the darkness of smoke with standard shades of grey placed in a suitable position. The charts are placed at such a distance from the observer that the black lines merge into the white background and produce for each shade a uniform grey. The numbers of the shades (the Ringelmann numbers) ranged from 0 (white) to 5 (black), the stages being by changes of 20% in obscuration of the background.
BS 2742 provides guidance on the use of BS Ringelmann charts to assess smoke emissions from unregulated processes. It is not suitable for calibrating Continuous Emissions Monitoring Systems. It is not applicable to processes whose emissions are regulated by EU Directives with stated Uncertainty.
BS 2742 should be used in conjunction with:
- BS 2742C Ringelmann chart
- BS 2742M Miniature smoke chart
Other measuring devices or charts are not suitable for use with BS 2742.
How has BS 2742 changed from the 1958 version?
- The 1972 Addendum has been removed: when it was developed, it was subject to uncertainty and in practice only should have only been applied to a limited number of coal burning chain grate stoker appliances (which are now rare).
- Added description of the manufacture/form of BS 2742C, Ringelmann chart and BS 2742M, Miniature smoke chart.
This revision does not alter the technical requirements from those stated in the 1958 and 1969 editions. The values, however, are now expressed in metric terms.
Users are reminded that this BS 2742 is only for use with the BS charts.
As the chart becomes soiled, the observed Ringelmann number of the smoke will be less than the true value. It is essential, therefore, that a used chart should be discarded as soon as it becomes appreciably soiled or discoloured.
Format of Ringelmann charts:
The BS Ringelmann charts are in two formats, standard and miniature. The standard chart is a series of four sections, printed with approximately 5% luminance ink on approximately 80% luminance card, to appear identical to Professor Ringelmann’s original charts when held at the recommended distance. There are also two control areas on the chart.
The miniature chart is a series of five paint swatches mounted on a card, the colours corresponding to those in BS 5252 and selected to appear identical to the standard chart (when in use). The card is supplied with an instructional envelope and with additional protection for the paint swatches.
Contents of BS 2742 include:
- Introduction
- Scope
- Normative references
- Use of the Ringelmann chart and miniature smoke chart
- Format of Ringelmann charts
- Chart holders and use of the chart BS 2742C
- Bibliography
List of figures
- Suitable holder for BS 2742C Ringelmann chart
- Sketch showing method of use of British Standard Ringelmann chart
- Suitable holder for BS 2742M miniature smoke chart
BS 2742:2009 replaces BS 2742:1969, which is withdrawn.
