ISO INTERNATIONAL STANDARD 9835 First edition 1993-03-15 Ambient air . Determination of a black smoke index Air ambiant - Détermination d'un indice de fumée noire Reference number ISO9835:1993(E) Copyright International Organization for Standardization No reproductio tworking permitted without license from IHS Not for Resale ISO9835:1993(E) Foreword Iso (the International Organization for Standardization) is a worldwide federation of national standards bodies (lsO member bodies). The work of preparing International Standards is normally carried out through IsO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International a vote. International Standard ISO 9835 was prepared by Technical Committee IsO/Tc 146, Air quality,Sub-Committee SC 3, Ambient atmospheres. AnnexAofthisInternationalStandardisforinformationonly @ISO 1993 by any means,electronic or mechanical, including photocopying and microfilm, without per- mission in writing from the publisher. International Organization for Standardization Case Postale 56· CH-1211 Geneve 20·Switzerland Printed in Switzerland ii CopyrightInternatinal Organizationfor Standardizaion without license from IHS Not for Resale INTERNATIONAL STANDARD ISO 9835:1993(E) Ambient air --- Determination of a black smoke index Scope where R is the intensity of reflected light from the This International Standard specifies a method for surface of a stained paper; measuring the black smoke index of an ambient air sample. The method is based on the staining effect Ro is the intensity of reflected light from the of particles which is produced when a sample of air surface of a clean paper; is drawn through a filter paper. A is the area of the stain on the filter paper, The method is intended for the measurement of a in square metres; black smoke index in the range 6 to 375 in the ambi ent atmosphere. It is based on the measurement of is the volume sampled, in cubic metres; reflectance. The method does not measure the mass concentration of particles directly. a is the absorption coefficient, in reciprocal metres. Thus, rearranging equation (1): 2 Definition A Ro D × Inl .. . (2) For the purposes of this International Standard, the 2V R following definition applies. The method specified in this International Standard 2.1 black smoke: Strongly light-absorbing, canbeusedtomeasuretheabsorptioncoefficienton particulate material suspended in the ambient atmos- anyfiltermaterial,buttheconversionofabsorption phere. coefficient or extinction coefficient to what is, by convention, known as the black smoke index, is NOTE 1 The major contributor to black smoke is soot purely an arbitrary operation which is carried out by particles; i.e. particles containing carbon in its elemental reference to tables or graphs. For further expla- form. nations,see annex A. 3 Principle and theory Air is drawn through a filter paper and the reflectance 4 Apparatus of the stain produced is measured. If it is assumed that reflected light from the surface of the filter paper has passed through the layer of light absorbent par- ticles twice, reflectance from the filter surface is 4.1 Sampling equipment. The sampler shall be analogous to the absorption of light by particles sus- designed for daily operation, or it shail be of an auto- pended in air in accordance with the equation matic type for continuous operation. Flow diagrams of alternative arrangements of sampling equipment R = Ro exp -2aV ..(1) are shown in figure 1. Details of the sampling equip- ment