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GB/T 458-2008 PDF in English


GB/T 458-2008 (GB/T458-2008, GBT 458-2008, GBT458-2008)
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GB/T 458-2008: PDF in English (GBT 458-2008)

GB/T 458-2008
GB
NATIONAL STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 85-010
Y 30
Replacing GB/T 5402-2003, GB/T 2679.13-1996, GB/T 458-2002
Paper and board - Measurement of air permeance
[ISO 5636-2.1984, Paper and board - Measurement of air permeance (medium
range) - Part 2. Schopper method; ISO 5636-3.1992, Paper and board -
Measurement of air permeance (medium range) - Part 3. Bendtsen method;
ISO 5636-5.2003, Paper and board - Measurement of air permeance and air
resistance (medium range) - Part 5. Gurley method, MOD]
ISSUED ON. AUGUST 19, 2008
IMPLEMENTED ON. MAY 01, 2009
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of PRC.
Table of contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 Terms and definitions ... 5 
4 Measurement procedures of Gurley method ... 6 
5 Measurement procedures of Schopper method ... 8 
6 Measurement procedures of Bendtsen method ... 10 
7 Test report ... 11 
APPENDIX A (Normative) Gurley air permeance tester ... 13 
APPENDIX B (Normative) Schopper air permeance tester ... 16 
Appendix C (Normative) Bendtsen air permeance tester ... 17 
Foreword
This standard, through modification, adopts ISO 5636-2.1984, Paper and
board - Measurement of air permeance (medium range) - Part 2. Schopper
method; ISO 5636-5.2003, Paper and board - Measurement of air permeance
and air resistance (medium range) - Part 5. Gurley method; AND ISO
5636-3.1992, Paper and board - Measurement of air permeance (medium
range) - Part 3. Bendtsen method.
As compared with ISO 5636-2.1984, ISO 5636-3.1992 and ISO 5636-5.2003,
the main differences are as follows.
- DELETE the introduction from international standards;
- CONSOLIDATE the scope of international standards;
- MOVE the instrument description in this standard into Appendix.
This standard the integration and modification of GB/T 458-2002 “Paper and
board - Measurement of air permeance (Schopper method)”, GB/T
2679.13-1996 “Paper and board - Measurement of air permeance (medium
range) - Bendtsen method” and GB/T 5402-2003 “Paper and board -
Measurement of air permeance and air resistance (medium range) - Gurley
method”, AND it replaces the above three standards.
Compared with GB/T 458-2002, GB/T 2679.13-1996 and GB/T 5402-2003, this
standard has the following changes.
- INTRODUCE the instrument structure and working principle in the form of
an appendix, in order to facilitate the rationality of the main contents of
this standard;
- In the Gurley method, DELETE the splint above type instrument because it
is out of date, and DELETE accordingly the relevant standard contents;
so the party using this standard please pay attention to the relevant
changes.
Appendix A, Appendix B and Appendix C of this Standard are normative
appendixes.
This standard was proposed by China Light Industry Association.
This standard shall be under the jurisdiction of the National Paper Industry
Standardization Technical Committee.
Paper and board - Measurement of air permeance
1 Scope
This standard specifies three methods for the measurement of air permeance
of paper and board. Gurley method, Schopper method, and Bendtsen method.
This standard is applicable to paper and board with air permeance between 1
× 10-2μm / (Pa • s) ~ 1 × 102μm / (Pa • s).
This standard does not apply to paper and board with a large surface
roughness which cannot be firmly clamped, such as crepe paper or corrugated
paperboard.
2 Normative references
The provisions in following documents become the provisions of this standard
through reference in this Standard. For the dated references, the subsequent
amendments (excluding corrections) or revisions do not apply to this standard;
however, parties who reach an agreement based on this standard are
encouraged to study if the latest versions of these documents are applicable.
For undated references, the latest edition of the referenced document applies.
GB/T 450 Paper and board - Sampling for testing and identification of
machine and cross direction wire side and felt side (GB/T 450-2008, ISO
186.2002, MOD)
GB/T 10739 Paper, board and pulps - Standard atmosphere for conditioning
and testing (GB/T 10739-2002, eqv ISO 187.1990)
3 Terms and definitions
The following terms and definitions apply to this standard.
3.1
Air permeance
It refers to, based on the specified conditions at the unit time and unit pressure
difference, the mean air flow passing through the unit area paper or board,
expressed in microns per Pascal seconds [1 μm / (Pa • s) = 1 mL / (m2 • Pa •
s)].
4 Measurement procedures of Gurley method
4.1 Preparation of test specimens
4.1.1 The sample shall be taken in accordance with GB/T 450.
4.1.2 The temperature and humidity treatment for sample shall be conducted
in accordance with the provisions of GB/T 10739.
4.1.3 From 10 samples, respectively CUT one specimen of the size 50 mm ×
50 mm.
Note. The measurement surface shall not have wrinkles, cracks, holes or other
appearance defects.
4.2 Measurement
4.2.1 The measurement shall be conducted under the same atmospheric
conditions as those used in the temperature and humidity treatment.
4.2.2 ADJUST the instrument to the horizontal position so that the two
cylinders are in a vertical position; and then CLAMP the smooth, hard, dense,
and impermeable metal or plastic sheet in between the two pore plates, to
check the tightness of the instrument. In accordance with 4.2.3, CONDUCT
inspection; after measurement for 5 h, the leaked air shall not be greater than
50 mL.
4.2.3 RAISE the inner cylinder so that its edge is on the support of the outer
cylinder. CLAMP the specimen; REMOVE the supporting device, in order to
lower down the inner cylinder to the position that can be floated.
When the inner cylinder is steadily lowered, START time keeping from the zero
scale, and MEASURE the time required by the initial two 50 mL interval (i.e.,
the interval from 0 mL to 100 mL) to pass the outer cylinder edge.
≤ 60 s. accurate to 0.2 s;
> 60 s to ≤ 180 s. accurate to 1 s;
> 180 s. accurate to 5 s.
Δp - Pressure difference between the two sides of the sample, in kilopascal
(kPa);
t - Measurement time, in seconds (s).
5.4 Precision
TAKE two specimens from the same sample; ARRANGE one operator to
conduct measurement in the same lab; AND the deviation of the mean values
of the two measurement results shall be within 10%.
6 Measurement procedures of Bendtsen method
6.1 Preparation of test specimens
6.1.1 The sample shall be taken in accordance with GB/T 450.
6.1.2 The temperature and humidity treatment for sample shall be conducted
in accordance with the provisions of GB/T 10739.
6.1.3 From 10 samples, respectively CUT one specimen of the size 50 mm ×
50 mm.
Note. The measurement surface shall not have wrinkles, cracks, holes or other
appearance defects.
6.2 Measurement
6.2.1 The measurement shall be conducted under the same atmospheric
conditions as those used in the temperature and humidity treatment.
6.2.2 PLACE the instrument on a stable workbench and ADJUST it level.
6.2.3 Based on the test sample, SELECT appropriate flow meter and working
pressure (the pressure as specified in this standard is 1.47 kPa).
6.2.4 After completing the leakage inspection and flow rate calibration,
CONNECT the flowmeter and measurement probe.
6.2.5 CLAMP the sample in between the annular plate and the gasket; and
RECORD the flowmeter reading 5 s after clamping.
6.2.6 CONDUCT measurement on the front of 5 samples and back of another
five samples. If there is a significant difference in the air permeance through
the front side and the back side, AND meanwhile it is required to report such
APPENDIX A
(Normative)
Gurley air permeance tester
A.1 Instrument
The instrument consists of an outer cylinder and an inner cylinder. The outer
cylinder contains a certain amount of sealing liquid, AND the inner cylinder is
free to slide in the outer cylinder. The outer cylinder has a height of 254 mm
and an inner diameter of 82.6 mm, in which 3 or 4 metal strips are arranged
erectly on the inner wall at same interval. The length of the metal strip is
between 190 mm and 245.5 mm, AND the cross section of the metal strip is
square of edge length 2.4 mm OR circle of diameter 2.4 mm; the metal strip is
used as the guide rail for the movement up and down of the inner cylinder. The
inner cylinder has a height of 254 mm, an outer diameter of 76.2 mm, an inner
diameter of 74.1 mm and a mass of (567 ± 0.5) g. The air pressure formed by
the self-gravity of the inner cylinder is applied to a sample sandwiched
between the plates having an aperture of (28.6 ± 0.1) mm.
The splint is located at the base, AND at the splint side with air pressure is
attached with a rubber liner, in order to avoid air leakage between the sample
surface and the splint. The liner is made from thin, resilient, oil resistant, and
oxidation resistant materials, AND has smooth and flat surfaces. The thickness
of the liner is 0.7...
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.