This standard specifies the method for determining the air permeability of highly permeable paper. This standard applies to paper with an air permeability greater than 1 X 102 μm/ (Pa·s). QB/T 1461-1992 Method for determining the air permeability of highly permeable paper QB/T1461-1992 Standard download decompression password: www.bzxz.net

Light Industry Standard of the People's Republic of China
Determination of air permeability of highly air permeable paper
Subject content and scope of application
This standard specifies the determination of air permeability of highly air permeable paper. This standard applies to paper with an air permeability greater than 1×10°μm/(Pa·s). 2 Reference standards
GB/T450 Sampling of paper and paperboard samples
GB/T10739 Standard atmosphere for handling and testing of pulp, paper and paperboard samples 3 Terminology
3.1 Air permeability
The performance of paper through air when there is a pressure difference between the two sides of the paper. 3.2 Air permeability
QB/T 1461-1992
Replaces QB/T 741—1979
The average air flow rate per unit area of ​​paper under specified conditions, unit time and specified pressure difference. It is expressed in cubic centimeters per square centimeter per second [cm2/(cm2·s)]. 3.3 Air permeability
The average air flow rate per unit area of ​​paper under specified conditions, unit time and unit pressure difference. It is expressed in micrometer per Pascal second Lμm/(Pa·s)).
[1 mL/(m2. Pa·s)=1 μm/(Pa*s))4 Principle
According to the specified method and test parameters, clamp the sample on the air inlet of the air permeability instrument, and then adjust the fan speed to make the two sides of the sample reach the specified pressure difference. The air permeability of the paper is measured according to the size of the orifice plate and the pressure difference between the two sides. 5 Instruments and equipment
The instrument for measuring air permeability should consist of the following parts (as shown in the figure). 5.1 A sample clamping device that can prevent the sample from deformation and air leakage at the edge. This device ensures a test area of ​​(38.5±0.2) cm2. Approved by the Ministry of Light Industry of the People's Republic of China on April 14, 1992, and implemented on December 1, 1992
Tilt manometer
Sample hole
QB/T1461--1992
Screw hole of partition
Exhaust fan
5.2 Speed-adjustable fan that sucks air to achieve the required pressure difference on both sides of the paper. Buffer plate
Air outlet
Vertical manometer
5.3 Tilt manometer and vertical manometer for measuring pressure difference. The range of the tilt manometer is 0~245Pa (25mm water column), and the range of the vertical manometer is 0~3922Pa (400mm water column). 5.4 Device for measuring air flow and a set of calibrated orifice plates, the flow deviation of which does not exceed ±2%. 5.5 Calibration plate for calibrating instruments.
6 Preparation and treatment of samples
6.1 Samples shall be taken in accordance with GB/T450.
6.2 Cut the sample into 5 pieces of 150mmX150mm. Note that there shall be no appearance defects such as wrinkles, cracks and holes on the surface to be tested. 6.3 Treat the cut samples in accordance with GB/T10739 and test them in this atmosphere. 7 Test steps
7.1 Calibration of instruments
7.1.1 Calibrate the instrument level.
7.1.2 Adjust the liquid level of the vertical pressure gauge and the inclined pressure gauge to zero. 7.1.3 Place the calibration plate on the sample hole of the instrument and fix it. 7.1.4 Open the arc door of the instrument, screw the standard orifice plate into the partition screw hole of the box body, and then close the door. 7.1.5 Turn on the power of the instrument, start the exhaust fan, and slowly adjust the speed of the exhaust fan with the help of the voltage regulator to make the liquid level in the inclined pressure gauge rise slowly and then stabilize at 13mm.
7.1.6 Observe the liquid level reading of the vertical pressure gauge, find out the corresponding air permeability from the pressure difference-flow chart, and check whether the measured air permeability is equal to the air permeability marked on the calibration plate. If the deviation exceeds ±2%, the cause should be found and eliminated. 7.2 Test of the sample
7.2.1 The pressure difference between the two sides of the paper is generally set to 127Pa (13mm water column). Under special conditions or special circumstances, the pressure difference can be set separately and stated in the report.
7.2.2 Select the corresponding orifice plate according to the air permeability range of the sample to be tested, so that the liquid level reading of the vertical pressure gauge is between 60~340mm water column.
7.2.3 Place the sample on the sample hole of the instrument and clamp the sample with a pressure ring. 7.2.4 According to the method of 7.1.5, make the liquid level of the inclined manometer stable at the specified pressure difference, and read the liquid level indication of the vertical manometer accurately, record it and be accurate to one small grid of the scale.
8 Calculationwww.bzxz.net
QB/T14611992
8.1 According to the liquid level reading of the vertical manometer, find out the air permeability of the sample from the pressure difference-flow chart, QCL/(m2·s)] and then convert it to cm*/(cm2.s) [1 L/(m2.s)=0. 1 cm*/(cm2 s)]. 8.2 The air permeability of the sample is calculated according to the following formula:
Where: P-air permeability of the sample, um/(Pa·s); QThe air permeability of the sample under a pressure difference of 13mm water column, cm2/(cm2·s). Test report
The test report shall include the following contents:
This standard number;
The model or name of the instrument;
The pressure difference between the two sides of the sample (Pa, mm water column); The test results are expressed in air permeability cm2/(cm2·s) or air permeability μm/(Pa·s); The arithmetic mean of the test results, accurate to three significant figures; The standard deviation or coefficient of variation of the test results, retaining two significant figures; Any operation that deviates from this standard during the test. 585
QB/T 1461-1992
Appendix A
Conversion factors of air permeability and air permeability in different units (reference)
The air permeability of paper can be converted according to the air permeability in different units. The commonly used units can be converted according to the following formula and coefficient. However, the air permeability measured under different pressure differences is related to the air permeability, but not equivalent. Therefore, the pressure difference used must be reported. Conversion formula
Where: P
Air permeability, μm/(Pa·s);
-conversion coefficient, select corresponding values ​​according to different pressure differences and different air permeability units; Q—air permeability, cm\/(cm2·s); L/(m2·s); ft3/(ft2·min). Conversion coefficient K value table
127Pa (13mm water column)
196Pa (20mm water column)
Additional instructions:
cm2/(cm2s)
This standard was proposed by the Paper Industry Department of the Ministry of Light Industry. This standard is under the jurisdiction of the National Paper Standardization Center. This standard was drafted by Shanghai Guofeng Paper Mill. The main drafters of this standard are He Dongsheng, Yao Yong, and Chen Kangqian. L/(m2·s)
ft'/(ft?min)
This standard refers to the American standard TAPPIT251cm-1985 "Determination of air permeability of porous paper fabrics and hand-coated paper sheets".
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