This standard specifies the method for determining the air permeability of leather. This standard is applicable to all kinds of leather. GB/T 4689.22-1996 Method for determining the air permeability of leather GB/T4689.22-1996 Standard download decompression password: www.bzxz.net

GB/T 4689.22--1996
The air permeability measured in this standard is an important indicator for measuring the hygienic performance of leather. This standard is proposed by the China Light Industry General Association.
This standard is under the jurisdiction of the National Fur Leather Standardization Center. This standard was drafted by the China Leather Industry Research Institute and co-drafted by the Standardization Research Institute of the China Light Industry General Association. The main drafters of this standard are Zhao Liguo, Li Ying and Lv Fengru. 13
1 Scope
National Standard of the People's Republic of China
Determination of air permeability of leather
Leather
Determination of air permeability This standard specifies the determination method of leather air permeability. This standard is applicable to various leathers.
2 Referenced Standards
GB/T 4689.22—1996
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard was published, the versions shown were valid. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest version of the following standards. GB4689.2--84 Leather-Air conditioning of test pieces for physical properties 3 Principle
Use a leather air permeability tester to form an air pressure difference in opposite directions on both sides of the leather sample, and measure the volume of air that passes through the sample under this condition. That is, the performance of air permeation rate per unit area, and the result is expressed in air permeability [mL/(cm2·h)]. 4 Instruments and tools
4.1 The main components of the leather air permeability tester (see Figure 1) should meet the following requirements:
a) Glass measuring cylinder: volume of 100cm, minimum scale of 1cm, open at the top, with a ground glass stopper, and an inverted U-shaped glass air duct and a drain pipe at the bottom, which is controlled by a water flow control switch. b) Air test chamber: made of metal, hollow cylindrical, inner diameter 3.56cm (equivalent to 10cm2), closed at the bottom, with an air guide port on the side; equipped with a threaded hollow annular cap with an inner diameter of 3.56cm on the top, which is airtight after the sample is loaded. c) Rubber air guide tube: inner diameter 8~10cm. Approved by the State Administration of Technical Supervision on December 17, 1996 14
Implementation on May 1, 1997
GB/T4689.22
1-ground stopper, 2-glass measuring cylinder, 3-air guide tube; 4-drain pipe, 5-water flow control switch, 6-air control switch; 7-rubber air guide tube, 8-air test chamber, 9-sample; 10-cap Figure 1
4.2 Stopwatch: accuracy 0.1s.
4.3 Steel mold knife: The inner wall is a right cylinder with a diameter of 5.5cm. The inner and outer surfaces of the knife edge form an angle of about 20°. The height of the wedge formed by this angle should be greater than the thickness of the leather.
5 Test steps
5.1 Instrument air tightness check
Turn off the water flow control switch and the air control switch, unplug the ground-mouth plug, add water to the measuring cylinder, and plug the ground-mouth plug tightly, then turn on the water flow control switch. If water does not flow out of the drain pipe, it indicates that the air tightness is good. 5.2 Blank test
Do not put in the sample first, turn off the water flow control switch and the air control switch, fill the measuring cylinder with (20±3)℃ distilled water, and plug the ground-mouth plug tightly. Turn on the water flow control switch, then turn on the air control switch, water flows out from the drain pipe, when the water level in the cylinder drops to the scale "0", start the stopwatch immediately, when the water level drops to the scale "100" (that is, 100mL has flowed out), stop the stopwatch immediately, and record the required time as t. (s). The blank test shall not be less than two times, and the difference between the two parallel measurement values ​​shall not be greater than 0.5s. Take the arithmetic mean as the measurement result, and retain one significant figure after the decimal point. Note: For distilled water at (20 ± 3) ℃, the time required for 100mL to flow through should be (20 ± 1) s. If it is not within this range, it should be adjusted. 5.3 Sample test
Cut the sample with a die knife, perform air conditioning according to GB4689.2, then place the sample in the air test room, tighten the cap, operate according to step 5.2, and record the time t(s) required for 100mL of water to flow out. Each sample is measured twice in parallel, and the difference between the two parallel measurement values ​​should not be greater than 0.5s. The arithmetic mean is taken as the measurement result, and the result is retained to one significant figure after the decimal point. Note: If the air permeability of the sample is very small and the time for air to pass through is more than 15 minutes, the horizontal position of the water in the measuring cylinder can be adjusted to below zero. Without waiting for 100mL of water in the measuring cylinder to flow out, record the amount of air that passes through within 5 to 10 minutes (the scale of the water column falling), and stop the test, and record the test time t (s) and the number of milliliters of water flow.
Results
GB/T4689.22-1996
Air permeability: expressed as the number of milliliters of air that permeates the unit area of ​​the sample in 1 hour. The calculation formula is as follows (1) and (2): K
Wherein: K—air permeability, mL/(cm2·h); to—time required for the blank test, s;
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10(t - t.)
t— to
t—time required for the sample to pass through 100 mL of air, s; 10-area of ​​the sample through which air permeates, cm. Ki=
Wherein: K,-
air permeability, mL/(cm2·h);
—time required for the blank test, s;
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100t, - nt.
t The time required for the sample to pass through n mL of air, s; n-
The amount of air that the sample passes through, mL.
The calculation result is rounded to the integer.
7 Test report content
a) This standard number;
b) Sample name, number, type, manufacturer (or trademark), production date; c) Test results (test time, final results); d) Abnormal conditions that occurred during the test;
e) Differences between the actual measurement method and this standard; f) Test personnel, date.
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