ISO 15906:2007

INTERNATIONAL ISO
STANDARD 15906
First edition
2007-05-01
Carbonaceous materials for the
production of aluminium — Baked
anodes — Determination of the air
permeability
Produits carbonés utilisés pour la production de l'aluminium — Anodes
cuites — Détermination de la perméabilité à l'air

Reference number
©
ISO 2007
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ii © ISO 2007 – All rights reserved

Foreword
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(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
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ISO 15906 was prepared by Technical Committee ISO/TC 226, Materials for the production of primary
aluminium.
Introduction
Anode performance in aluminium reduction cells can be partially characterized by the measurement of the gas
permeability. Higher permeability allows attack and consumption of the anode by air and C0 , thus shortening
the life and overall performance of the anode.
iv © ISO 2007 – All rights reserved

INTERNATIONAL STANDARD ISO 15906:2007(E)

Carbonaceous materials for the production of aluminium —
Baked anodes — Determination of the air permeability
1 Scope
This International Standard describes a method for the measurement of the air permeability of baked anodes,
by determining the resistance to airflow of a specimen of specified volume at room temperature, within the
range of air permeability between 0,01 nPm (nanoperms) and 10 nPm.
“Green” anodes are considered to be impermeable to gas. Therefore, this test is most applicable to “baked”
carbon material.
NOTE This method can also be used for measuring other carbon materials (e.g. microporous carbon materials), but
precision statements are not available for other carbon materials.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 8007-2:1999, Carbonaceous materials used in the production of aluminium — Sampling plans and
sampling from individual units — Part 2: Prebaked anodes
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
sample
portion of carbon from a baked anode
3.2
test specimen
article prepared from a sample
4 Principle
The air permeability of a sample is determined by a comparative method. The time necessary to draw a
specified volume of air through the test specimen is measured. This time is compared to the time necessary to
draw a specified volume of air through a standard with known air permeability. This comparison yields the air
permeability of the sample material.
5 Apparatus
5.1 Callipers, with 0,01 mm reading precision.
5.2 Air permeability unit equipped as in 5.2.1 to 5.2.3.
5.2.1 Membrane vacuum pump, with an inlet to generate vacuum down to 100 mbar, and an outlet to
generate high pressure up to 4 bar. The maximum flow rate has to reach 25 l/min.
5.2.2 Permeability cell, as shown in Figure 1. The cell is designed to ensure an airtight sealing around the
periphery of the sample. A rubber tube is forced as a seal against the cylindrical test specimen by means of
compressed air. The porous filter-paper and the sponge-rubber protect the vacuum pump from particles
and/or dust from the sample.
5.2.3 U-tube manometer, with light fork sensors as shown in Figure 2.
The U-tube is directly linked with the vacuum pump
...