ISO INTERNATIONAL STANDARD 4785 First edition 1997-05-01 ANSI internat Doc Ser Laboratory glassware -- Straight-bore glass stopcocks for general purposes Verrerie de laboratoire - Robinets en verre a alesage droit pour usage general ISO Reference number ISO 4785:1997(E) vided by IHS under license with ISO Not for Resale ISO 4785:1997(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, 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 Standard requires approval by at least 75 % of the member bodies casting a vote. This International Standard ISO 4785 has been prepared by Technical Committee ISO/TC 48, Laboratory glassware and related apparatus, Subcommittee sc 2, General laboratory glassware (other than measuring apparatus). Annex A of this International Standard is for information only @ISO1997 reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Organization for Standardization 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 Copyright Inte nse from IHS Not for Resale ISO 4785:1997(E) INTERNATIONALSTANDARD ISO Laboratory glassware - Straight-bore glass stopcocks for general purposes Scope 7 This Internationai Standard specifies requirements and dimensions for two series of glass straight-bore stopcocks for general-purpose use. The stopcocks are defined by their nominal (bore)diameter and large end diameter and length of the ground zone.It is recommended that, in national standards, only one of the series should be specified. NOTE - Annex A lists additional international Standards for other general-purpose laboratory glassware. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and IsO maintain registers of currently valid International Standards. Is0719:1985, Glass —Hydrolytic resistance of glass grains at 98°C -- Method of test and classification. IsO3585:1991, Borosilicateglass3.3—Properties. Iso 4803:1978, Laboratoryglassware—Borosilicate glass tubing. 3 Groundzone 3.1 The taper of the ground zone shall be such as to give one increment on the diameter for ten increments on the axial length, with a tolerance of ± 0,o06 on the diameter increment i.e. a taper of(1±0,006)/10. NOTES 1 This tolerance is in agreement with the relevant requirement of IS0 383. Annex B in IS0 383:1976 describes a leakage test with air which may be used to check the tightness of the ground zone. 2 Actual manufacturing techniques normally result in a tighter tolerance than that given above, but owing tothelack of experimental evidence itisnot yetpossibleto reducethe specifiedvalue. 3.2 The centreline average height of the ground surface shall not exceed 1 μm and should preferably be less than 0,5 μm. 1 Copyright International Organization for Standardization No rep