SIST ISO 4785:1998

INTERNATIONAL
IS0
STANDARD
First edition
1997-05-01
Laboratory glassware - Straight-bore
glass stopcocks for general purposes
Verrerie de laboratoire - Robinets en verre & al&age droit pour usage
g&&al
Reference number
IS0 4785: 1997(E)
IS0 4785:1997(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide federation of national
standards bodies (IS0 member bodies). The work of preparing International Standards is
normally carried out through IS0 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. IS0 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 IS0 4785 has been prepared by Technical Committee lSO/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.
0 IS0 1997
All rights reserved. Unless otherwise specified, no part of this publication may be
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
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Internet centraI@iso.ch
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Printed in Switzerland
ii
IS0 4785:1997(E)
INTERNATIONAL STANDARD @ IS0
- Straight-bore glass
Laboratory glassware
stopcocks for general purposes
1 Scope
This International 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.
Annex A lists additional International Standards for other general-purpose laboratory glassware.
NOTE -
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 IS0 maintain registers of currently valid
International Standards.
IS0 719:1985, Glass - Hydrolytic resistance of glass grains at 98OC - Method of test and
classification.
IS0 3585:1991, Borosilicate glass 3.3 - Properties.
IS0 4803: 1978, Laboratory glassware - Borosilicate glass tubing.
3 Ground zone
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 & 0,006 on the diameter increment i.e. a taper
of (1 + 0,006)/l 0.
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
to the lack of experimental evidence it is not yet possible to reduce the specified value.
3.2 The centreline average height of the ground surface shall not exceed 1 pm and should
preferably be less than 0,5 pm.

@ IS0
IS0 4785:1997(E)
NOTE - The “centreline average height” of the ground surface is the average value R, of the surface
roughness as defined in IS0 468.
4 Dimensions and series of sizes
4.1 The nominal diameters of series I stopcocks shall be as follows (given in millimetres):
1 - I,5 - 2,5 - 4 - 6 - IO
This is the R 5 series of preferred numbers.
NOTE -
4.2 The nominal diameters of series II stopcocks shall be as follows (given in millimetres):
l-1,5-2-3-4-5-6-8-10
4.3 The dimensions and tolerances of the ground zone shall be as shown in table 1 and figure 1.
4.4 The allocation of bore diameters to key and barrel dimensions shall be as shown in table 2.
5 Side arms
The side arms shall be fused to the barrel so as to enable a pin of thickness 0,8 times the
nominal bore to fit at leas
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