ISO 23714:2014
(Main)Pulps — Determination of water retention value (WRV)
Pulps — Determination of water retention value (WRV)
ISO 23714:2014 specifies a procedure for the determination of the water retention value (WRV) of all kinds of pulp.
Pâtes — Détermination de la valeur de rétention d'eau (VRE)
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 23714
Second edition
2014-02-01
Pulps — Determination of water
retention value (WRV)
Pâtes — Détermination de la valeur de rétention d’eau (VRE)
Reference number
ISO 23714:2014(E)
©
ISO 2014
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ISO 23714:2014(E)
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ii © ISO 2014 – All rights reserved
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ISO 23714:2014(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 2
7 Sampling . 3
8 Preparation of sample . 3
9 Procedure. 3
9.1 General . 3
9.2 Forming in a Büchner funnel . 3
9.3 Centrifuging the test pad . 3
10 Calculation . 4
11 Test report . 4
Annex A (informative) Test-pad-holding units
........................................................................................................................................... 5
Annex B (informative) Precision . 7
© ISO 2014 – All rights reserved iii
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ISO 23714:2014(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO 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
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 6, Paper, board and pulps.
This second edition cancels and replaces the first edition (ISO 23714:2007) which has been revised to
add a new precision statement that complies with the requirements of ISO/TR 24498.
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ISO 23714:2014(E)
Introduction
The water retention value (WRV) is an empirical measure of the capacity of a test pad of fibres to hold
water. The WRV increases with increasing beating because of internal fibrillation, a widening of the small
internal pores, and delaminations, which has been called “swelling” and which occurs concurrently with
the development of external fibrils, which also serve to hold additional water.
This test can be useful for the pulp producer as a guide to the influence of the pulping process on the
fibre produced and the papermaking potential of the pulp. It is also useful for the papermaker as a
measure of the efficiency of pulping and refining.
© ISO 2014 – All rights reserved v
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INTERNATIONAL STANDARD ISO 23714:2014(E)
Pulps — Determination of water retention value (WRV)
1 Scope
This International Standard specifies a procedure for the determination of the water retention value
(WRV) of all kinds of pulp.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 5263-1, Pulps — Laboratory wet disintegration — Part 1: Disintegration of chemical pulps
ISO 5263-2, Pulps — Laboratory wet disintegration — Part 2: Disintegration of mechanical pulps at 20 °C
ISO 5263-3, Pulps — Laboratory wet disintegration — Part 3: Disintegration of mechanical pulps at > 85 °C
ISO 7213, Pulps — Sampling for testing
ISO 14487, Pulps — Standard water for physical testing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
water retention value
ratio of the mass of water retained after centrifugation under specified conditions by a wet pulp sample
to the oven-dry mass of the same pulp sample
4 Principle
A test pad consisting of pulp fibres is formed by dewatering a pulp suspension on a glass-fibre filter.
The test pad is centrifuged under a specified centrifugal force for a specified time, weighed, dried, and
weighed again. The WRV is calculated from the wet mass of the centrifuged test pad and the dry mass
of the test pad.
NOTE The results obtained from a rewetted pulp will not be the same as those from a corresponding never-
dried pulp.
5 Reagents
5.1 Standard water, as specified in ISO 14487.
If any other type of water is used, this shall be reported.
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ISO 23714:2014(E)
6 Apparatus
6.1 Laboratory centrifuge, with a swing-out head and buckets, made of an inert material such as steel
or anodized aluminium, about 100 ml in volume, and about 45 mm in inner diameter.
2
The centrifugal force shall be (3 000 ± 50) g (g is the acceleration due to gravity, i.e. 9,81 m/s ) at the
position of the test pad, approximately 15 mm from the bottom of the bucket. The centrifuge shall be
equipped with a timer and a brake.
It is desirable that the centrifuge should maintain a working temperature of (23 ± 3) °C.
2
NOTE If g is the acceleration due to gravity, i.e. 9,81 m/s , then the rotational frequency is obtained using
Formula (1):
1
Z×896 2
N = (1)
r
where
−1
N is the rotational frequency, in min or r/min;
Z is the centrifugal force, (3 000 ± 50) g;
r is the distance between the centre of rotation and the filtration plane of the glass filter (radius of gyra-
tion), in metres.
6.2 Büchner funnel or similar funnel, made of non-corrosive material, the perforated bottom of
which shall be flat, and having an internal diameter larger than 30 mm.
6.3 Wire cloth, of glass-fibre filter, e.g. Whatman grade GF/C filter or equivalent.
6.4 Suction flask, connected to a water suction pump or similar device for vacuum filtration applied to
the Büchner funnel.
6.5 Set of test-pad-holding units.
The holding unit is a metal tube, (30 ± 5) mm in inner diameter, with a phosphor-bronze wire screen
attached to one end. The wire
...
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