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Ref. No. : ISO/R 81 1-1968 (E)
IS0
INTERN AT I ON A L ORGAN IZATl O N FO R STA N DARD IZATl O N
IS0 RECOMMENDATION
R 811
METHOD OF TEST FOR RESISTANCE OF FABRICS
TO PENETRATION BY WATER
(Hydrostatic head test)
1st EDITION
August 1968
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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BRIEF HISTORY
The IS0 Recommendation R 81 1, Method of test for resistance of fabrics to penetration by
water (Hydrostatic head test), was drawn up by Technical Committee ISO/TC 38, Textiles, the
Secretariat of which is held by the British Standards institution (BSI).
Work on this question by the Technical Committee led, in 1964, to the adoption of a Draft
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I SO Recommendation.
t
In December 1966, this Draft IS0 Recommendation (No. 1051) 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 Israel Spain
Belgium Japan Sweden
Brazil Korea, Rep. of Switzerland
Czechoslovakia Netherlands Thailand
Denmark New Zealand Turkey
France Norway U.A.R.
GelXlany Poland
United Kingdom
Hungary Romania U.S.S.R.
India South Africa,
Iran Rep. of
Three Member Bodies opposed the approval of the Draft :
Argentina
Canada
Italy
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council,
which decided, in August 1968, to accept it as an IS0 RECOMMENDATION.
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ISO/R 811-1968 (E)
IS0 Recommendation R 811 August 1968
METHOD OF TEST FOR RESISTANCE OF FABRICS
TO PENETRATION BY WATER
( Hydrostatic head test)
1. SCOPE
This IS0 Recommendation describes a method of test for the resistance of fabrics to penetration by
water. The method is primarily intended for water-repellent fabrics which are permeable to air.
2. PRINCIPLE
The hydrostatic head supported by a fabric is a measure of the opposition to the passage of water
through the fabric. A specimen is subjected to a steadily increasing pressure of water on one face,
under standard conditions, until penetration occurs in three places. The pressure at which the water
penetrates the fabric at the third place is noted.
The result is immediately relevant to the behaviour of fabric articles which are subjected to water
pressure for short or moderate periods of time.
3. APPARATUS
3.1 The apparatus used for the test should be designed to comply with the following conditions.
3.1.1 It should be possible to clamp the specimen of fabric in such a way that
- it is horizontal,
- an area of the fabric of 100 cm2 is subjected to steadily increasing water pressure on
one face,
- no leakage of water takes place at the clamps during the test period (see Appendix,
clause Z.l),
- the specimen does not slip in the clamps,
- any tendency for penetration to occur at the clamped edge of the specimen is minim-
ised (see Appendix, clause Z.1).
3.1.2 The water in contact with the test specimen should be distilled water maintained at either
20 ?r 1 "C or 27 ?r 1 OC. *
3.1.3 The rate of increase of water pressure should be 10 f 0.5 cm head of water per minute.
3.1.4 A manometer connected to the testing head (s) should allow pressures to be read to an
accuracy of 0.5 cm head of water (see Appendix, clause 2.2).
~~~
The use of water at the higher temperature will yield lower values of hydrostatic head; the magnitude of this
effect may vary from fabric to fabric.
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ISO/R 811-1968 (I
4. CONDITIONING
Before testing, condition t
...