ISO INTERNATIONAL STANDARD 4174 Second edition 1998-02-15 Cereals, oilseeds and pulses Measurement of unit pressure loss in one-dimensional air flow through bulk grain Céréales, graines oleagineuses et légumineuses - Mesurage des pertes de charge unitaires dans un écoulement d'air unidimensionnel a travers une charge de grains ISO Referencenumber ISO 4174:1998(E) by IHS under lic Not for Resale ISO 4174:1998(E) Foreword IsO (the International Organization for Standardization) is a worldwide federationofnationalstandardsbodies(lsOmemberbodies).Theworkof 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 (lEC)onallmattersofelectrotechnicalstandardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 4174 was prepared by Technical Committee ISO/TC 34, Agricultural food products, Subcommittee SC 4, Cereals and pulses This second edition cancels and replaces the first edition (IsO 4174:1980), which has been technically revised. AnnexAofthisInternational Standardisforinformationonly @ISO1998 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced microfilm, without permission in writing from the publisher. InternationalOrganizationforStandardization Case postale 56· CH-1211 Geneve 20 · Switzerland Internet [email protected] X.400 C=ch; a=400net; p=iso; 0=isocs; S=central Printed in Switzerland ense from IHS Not for Resale @ ISO ISO 4174:1998(E) Introduction porous medium has been considered for grain (in particular for cereals and pulses), and such application appears to be sufficiently well verified. The value of the unit pressure loss depends on the dimensions, porosity, well as the temperature, relative humidity, density and entering velocity of the air. Experiments carried out by dimension categories allow two parameters to be eliminated: the moisture content and the shape (granulometry). The parameters that remain enable the characteristic coefficients of the medium to be determined: porosity and specific area. The results obtained may be used to predict the pressure losses for various densities at a specific point. ili itted without license from IHS Not for Resale