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UDC 648.4 Ret. No.: lSO/ R 250 - 1962 (E)
IS0
FOR STAN DA RD I Z AT I O N
I NT ERN AT1 ON AL O RG A N IZATl O N
IS0 RECOMMENDATION
R 250
SAMPLING OF RAW NATURAL RUBBER
1st EDIT10 N
March 1962
COPYRIGHT RESERVED
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 member 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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RRIFiF HISTORY
The TSO Recommendation R 250, Sampling of Raw Natural Rubber, was drawn up
by Technical Committee ISO/TC 45, Ri4bber, the Secretariat of which is held by the British
Standards Institution (B.S.T.).
Work on this question by the Technical Committee began in 1956 and led, in 1958, to
the adoption of a Draft IS0 Recommendation.
In December 1959, this Draft IS0 Recommendation (No. 344) was circulated to all
the IS0 Member Bodies for enquiry. It was approved, subject to a few modifications of
an editorial nature, by the following Member Bodies :
Australia Tndia Sweden
Austria Israel Switzerland
Burma Italy United Kingdom
Chile Japan U.S.A.
Colombia Mexico U.S.S.R.
Czechoslovakia Netherlands Yugoslavia
Germany Portugal
Hungary Spain
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in March 1962, to accept it as an IS0 RECOMMENDATION.
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lSO/R 250 - 1962 (E)
IS0 Recommendation R 250 March 1962
SAMPLING OF RAW NATURAL RUBBER
1. SCOPE
This IS0 Recommendation covers the sampling of raw natural rubber, whether in the form of
bales or loose sheets (including crepe), and the allocation of portions of the sample for specific
tests. The sampling of loose sheets is normally carried out only in rubber-producing countries.
2. DEFINITIONS
2.1 Lot. An assembly of bales or loose sheets characterized by some distinctive common
feature.
NOTE. -All bales bearing the same marks may be regarded as a lot unless there are obvious signs
of heterogeneity. Loose sheets can be regarded as forming a lot only if they are obtained from
a single bulking of latex and have been dried in air or smoke under the same conditions.
2.2 Sample. A group of bales or loose sheets selected to represent a lot.
2.3 Piece. Quantity of rubber taken from a bale of the sample to represent that bale, or
quantity of rubber taken from the loose sheets of the sample and combined to represent
the sample.
2.4 Test portion. Portion of rubber taken from a piece or pieces for subjection to a test,
3. METHOD OF SELECTING THE SAMPLE
For lots where no uniformity in quality has been established, the only safe assessment of the
quality of the lot is that based on 100 per cent sampling, i.e., the lot becomes the sample.
In most cases, practical considerations impose a limit on what is possible, and the following
levels of sample size are recommended.
Rubber in the form of loose sheets. The number of sheets to be taken as the sample is 10 per
3.1
cent or 40 sheets, whichever is the smaller number, and the sheets are chosen at approxi-
mately uniform intervals when sorting from the stack of sheets
...