ISO 4795:1996

SLOVENSKI STANDARD
SIST ISO 4795:1998
01-april-1998
6WHNOR]DWHUPRPHWUVNHEXþNH
Glass for thermometer bulbs
Verre pour réservoirs de thermomètres
Ta slovenski standard je istoveten z: ISO 4795:1996
ICS:
71.040.20 Laboratorijska posoda in Laboratory ware and related
aparati apparatus
SIST ISO 4795:1998 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST ISO 4795:1998

---------------------- Page: 2 ----------------------

SIST ISO 4795:1998
INTERNATIONAL IS0
STANDARD 4795
First edition
1996-l 2-I 5
Glass for thermometer bulbs
Verre pour rkservoirs de thermomktres
Reference number
IS0 4795: 1996(E)

---------------------- Page: 3 ----------------------

SIST ISO 4795:1998
IS0 4795: 1996(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 4795 has been prepared by Technical Committee lSO/TC 48,
Laboratory glassware and related apparatus, Subcommittee SC 3, Thermometers.
Annex A forms an integral part of this International Standard. Annexes B, C and D are for
information only.
0 IS0 1996
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
Case postale 56 l CH-1211 Geneve 20 l Switzerland
Internet: central@isocs.iso.ch
x.400: c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
ii

---------------------- Page: 4 ----------------------

SIST ISO 4795:1998
IS0 4795:1996(E)
INTERNATIONAL STANDARD 0 IS0
Glass for thermometer bulbs
1 Scope
This International Standard specifies the physical and chemical characteristics and the marking of
thermometric glass and the test methods to be used for the selection of glass for the manufacture
of the bulbs of liquid-in-glass thermometers.
It is not applicable to the glass used in parts of the thermometer other than the bulb (e.g. the
stem). However, the glass used for the other parts can be identical to that used for the bulb.
The coefficient of linear thermal expansion of the bulb glass should not differ from that of the
glass intended for the stem by more than 0,2 x IO4 K-‘.
2 Normative references
The following standards contain provisions which, through references 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 98 OC - Method of test and
classification.
IS0 7884-7:1987, Glass - Viscosity and viscometric fixed points - Part 7: Determination of
annealing point and strain point by beam bending.
3 Definitions
For the purposes of this International Standard, the following definitions apply.
3.1 strain point, ef4: The temperature determined in accordance with IS0 7884-7.
NOTE - By the beam-bending method, the viscosity of glass at the strain point may be evaluated as
1 O’4S7 dPa.s.
3.2 zero-point correction, K: Correction of the thermometer at 0 OC:
where find is the temperature indicated.

---------------------- Page: 5 ----------------------

SIST ISO 4795:1998
IS0 4795: 1996(E) 0 IS0
3.3 zero-point depression: Change of the zero-point correction after heating and fast cooling of
the thermometer.
4 Maximum temperature of use
The maximum temperature recommended for use shall not exceed (e,, -130) “C, where 8,, is the
strain point determined in accordance with the method given in IS0 7884-7.
Requirements
5
5.1 Stability
The indication at 0 OC of a suitable test thermometer having a bulb made of the glass under
consideration shall not change by more than 2 OC after exposure to the maximum temperature
recommended for use (see clause 4) for 500 h.
This stability requirement can be determined in accordance with annex B.
5.2 Zero-point depression
When tested in accordance with the procedure given in annex A, a thermometer having a bulb
made of the glass under consideration shall have an average zero-point depression not exceeding
O,O5 OC for “normal glass” or 0,03 OC for borosilicate glass.
NOTE -The zero-point depression of some types of thermometric glass is given in annex C.
5.3 Chemical resistance
When tested according to the procedure and classification given in IS0 719, the glass shall
comply with the requirements of class HGB 3 or better.
6 Marking
complying with this International Standard shall be identified according
6.1 Thermometric glass
given in 6.2 and 6.3.
to either of the schemes
6.2 The manufacturer of the thermometric glass shall incorporate an identification stripe or stripes
in accordance with the approved list shown in table D.l (see annex D).
6.3 The manufacturer of the thermometer shall mark it with an identification alphanumeric code in
accordance with the approved list shown in table D.l (see annex D) and shall, on request, supply
a certificate of conformity provided by the manufacturer of the thermometric glass.
NOTE 1 The list of approved identification stripes and identification codes will be maintained under the
responsibility of the secretariat for this International Standard, on the basis of data provided by the national
test authorities or notified bodies responsible for testing and certification of thermometric glass.
NOTE 2 Manufacturers wishing to claim, for a thermometric glass not listed in table D.l, compliance with
the requirements of this International Standard, should apply to their national standards body, who will
register the glass with the secretariat for this International Standard. A certificate from a national test
authority or notified body that the thermometric glass to be registered corresponds to the requirements of
this International Standard is rec
...