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IS0
I N T E R N AT I O N A L O R G A N I2 AT I ON FOR S TA N D A R D I ZATl O N
IS0 RECOMMENDATION
R 718
METHODS FOR THERMAL SHOCK TESTS
ON LABORATORY GLASSWARE
1 st EDITION
May 1968
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The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a mmber of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 71 8, Methods for thermal shock tests on laboratory glass
ware, was drawn up by Technical Committee ISO/TC 48, Laboratory glassware and related
apparatus, the Secretariat of which is held by the British Standards Institution (BSI).
Work on this question by the Technical Committee began in 1950 and led, in
a Draft IS0 Recommendation.
1958, to the adoption of
This first Draft IS0 Recommendation (No. 351) was circulated in April 1960
to all the IS0 Member Bodies for enquiry. As the results of this consultation were
not considered satisfactory, the Technical Committee presented a second Draft IS0
Recommendation which was circulated to all the IS0 Member Bodies in December 1963
and which was approved, subject to a few modifications of an editorial nature, bythe
following Member Bodies :
Sweden
Argentina Hungary
Australia India Switzerland
Austria Israel Turkey
U.A.R.
Belgium Italy
Brazil United Kingdom
Japan
Canada Korea, Rep. of U.S.A.
Chile Netherlands U.S.S.R.
Yugoslavia
Colombia New Zealand
Czechoslovakia Poland
Greece Spain
Two Member Bodies opposed the approval of the Draft :
France
v
Germany
The second Draft IS0 Recommendation was then submitted by correspondence
to the IS0 Council which decided, in May 1968, toacceptit asan IS0 RECOMMEND-
i ATION.
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ISO/R 718-1968 (E)
IS0 Recommendation R 718 May 1968
METHODS FOR THERMAL SHOCK TESTS
ON LABORATORY GLASSWARE
1. SCOPE
This IS0 Recommendation describes general methods of test intended to assess the
resistance of glassware used in laboratories to a shock arising from a predeter-
mined change in temperature.
Three methods are recommended :
(I) Method A, for testing whole articles at temperature differences of less
than 100 degrees Celsius.
Method B, for testing whole articles at temperature differences of I00
(2)
degrees Celsius or more.
(3) Method C, for testing the rims of articles.
NOTE. - Method B is recommended also for testing small articles, at temperature differences of less than 100
degrees Celsius, in cases for which Method A is inappropriate.
2. DEFINITION
The thermal shock is measured by the difference between the upper temperature t, ,
to which the article is heated, and the lower temperature t, of the cold water bath,
in which the article is placed.
3. SAMPLING
The number of articles to be taken as a sample from a consignment should be speci-
fied in the appropriate national standard for the article under test or, in default,
this should be agreed between the parties concerned. The articles comprising the
sample should be taken at random from the whole consignment.
4. APPARATUS
4.1 Method A. For testing whole &ticles at temperature differences less than 100 degrees Celsius
Two baths of a capacity of at least 5 litres are required, one of the baths pro-
vided with a means of heating. Each bath should be provided with a suitable stirrer
or other device to ensure that a constant temperature can be maintained through-
out the bath, and with a laboratory thermometer capa
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