ISO INTERNATIONAL STANDARD 1608-2 Second edition 1989-12-01 Vapour vacuum pumps - Measurement of performance characteristics Part 2 : Measurement of critical backing pressure Pompes a vide a jet de vapeur - Mesurage des caracteristiques fonctionnelles Partie 2 : Mesurage de la pression critique de refoulement Referencenumber ISO 1608-2 : 1989 (E) ISO 1608-2 : 1989 (E) Foreword ISo (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO 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, govern mental 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 Standardsadoptedbythetechnical committeesare circulatedto the member bodies for approval before their acceptance as International Standards by the Iso Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 1608-2 was prepared by Technical Committee ISO/TC 112, Vacuum technology. This second edition cancels and replaces the first edition (IS0 1608-2 : 1978), of which it constitutes a technical revision. iso 1608 will consist of the following parts, under the general title Vapour vacuum pumps - Measurement of performance characteristics: Part 1: Measurement of volume rate at flow (pumping speed) Part2:Measurementof critical backingpressure Part3:Gasflowrates ISO1989 Allrights reserved. No part of this publication may be reproduced or utilized in any form or by any means,electronic ormechanical,includingphotocopying and microfilm,without permission in writing from the publisher. InternationalOrganizationforStandardization Case postale 56 . CH-1211 Geneve 20 . Switzerland Printed in Switzerland i ISO 1608-2 : 1989 (E) Introduction characteristics of vapour vacuum pumps are, as far as possible, carried out by uniform procedures and under uniform conditions. It is hoped that, as a result, measurements conducted by different manufacturers or in different laboratories, and statements of performance quoted in manufacturers' literature, will be on a properly comparable basistothebenefitofbothuserand manufacturer. It is envisagedthatthecompleteInternational Standard will,induecourse,deal com prehensively with the measurement of a wide range of performance characteristics of more restricted scope may be implemented with the least possible delay, IsO 1608 is published in parts.