This standard specifies the method for measuring the maximum pore size of filter paper and paperboard using an automatic maximum pore size determination instrument. This standard is applicable to filter paper and filter plates with a thickness of 0.10 mm to 3.50 mm that can be safely wetted by a wetting agent. GB/T 2679.14-1996 Determination of the maximum pore size of filter paper and paperboard GB/T2679.14-1996 Standard download decompression password: www.bzxz.net

GB/T2679.14—1996
This standard adopts the British national standard BS6410 (Section 2.14.2): 1991 "Method for determination of the maximum equivalent aperture", and combines the characteristics of the domestically developed instrument for automatic determination to formulate the standard for "Determination of the maximum aperture of filter paper and paperboard". The determination principle, pressure sensor range and pressure rise speed of this standard are the same as those of the British standard, but the wetting agent used is different. In addition, the British standard is manually determined, while the operation of this standard, including temperature correction and result display, is all automatic. This standard was proposed by the China Light Industry General Association.
This standard is under the jurisdiction of the National Paper Standardization Technical Committee. The drafting unit of this standard: China Pulp and Paper Industry Research Institute. The main drafters of this standard: Zhao Huang, Liu Huiyin, Xu You, Shan Xiaoxuan, Chen Xi. 338
1 Scope
National Standard of the People's Republic of China
Filter paper and filterboard--Determination of maximum pore diameter
Filter paper and filterboard--Determination of maximum pore diameterGB/T 2679. 14--1996
This standard specifies the method for determining the maximum pore diameter of filter paper and filterboard using an automatic maximum pore diameter determination instrument. This standard is applicable to filter paper and filter boards with a thickness of 0.10mm to 3.50mm that can be completely wetted by a wetting agent. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB450-89 Paper and paperboard test samples
3 Terminology
3.1 Porosity
The pores of paper are composed of capillary channels of various shapes, twists and turns, extending in all directions, and of varying lengths. 3.2 Aperture
The pore size of paper refers to the pore diameter equivalent to the cylindrical capillary with the same capillary pressure, and is therefore an equivalent pore size. The largest of these is the maximum pore size (pmax).
4 Principle
4.1 According to the principle of capillary action, as long as the pressure at which the first bubble emerges when the air is driven out of the liquid in the largest capillary in the paper is measured, the maximum pore size of the sample can be calculated by using the known surface tension of the liquid at the measurement temperature and the capillary equation. 4.2 The surface tension of the test solution should be low, and it should be able to fully wet the filter paper without affecting the organizational structure of the paper. It should be non-toxic and have low volatility. Suitable liquids include isopropyl alcohol and kerosene. The surface tension of isopropanol =%-AY·t=22.90-0.079t (mN/m) The surface tension of kerosene =27.19--0.092t (mN/m).
5 Instrumentwww.bzxz.net
Adopt QZH-2 automatic maximum aperture measuring instrument (see Figure 1). Approved by the State Administration of Technical Supervision on June 25, 1996 and implemented on January 1, 1997
Front view
Rear view
Sealing ring
8 Middle mother
Liquid injection detection
Liquid injection end line
Main parameters:
GB/T 2679. 14-1996
Testing gland
Reset drain
Pressure speed adjustment
Liquid filling adjustment
a) Determination of filter paper thickness range (0.10～3.50)mm; b) Test area (20.0±0.5)cm2;
c) Clamp ring inner diameter (50.0±0.5)mm;
d) Clamp ring outer diameter (54.0±0.5)mm;
e) Liquid height on the sample (28.7±0.4)mm. 6 Calibration of the instrument
6.1 Place the instrument horizontally.
Display window
Fuse box
6.2 Add wetting agent from the liquid filling hole, and the liquid level in the liquid storage cup should be between the two red lines. Detection cup
Printer
Selection switch
6.3 Turn on the power, preheat for 20-30 minutes, unscrew the sealing ring, remove the detection cover, and adjust the zero point. 6.4 Verification
Power switch
Power plug
Use standard hole foil (aluminum foil with small holes on 0.17mm thick) for testing. The pressure measured 3-4 times is qualified if the standard deviation is within 10 Pa (i.e. 1mm water column).
Sampling and processing
7.1 Sampling shall be taken in accordance with the provisions of GB450--89 or the provisions of the product standard inspection rules. 7.2 From the sampled paper, cut 6-10 samples (numbered) with a diameter of about 60mm at equal distances along the horizontal paper width and keep them clean.
7.3 Soak the sample with a wetting agent.
8 Test method
8.1 Test preparation (see Figure 1).
GB/T2679.14—1996
8.1.1 Connect the power supply, turn on the power switch, and warm up the instrument and reset it to zero. 8.1.2 Check the liquid storage cup to ensure that the liquid level is between the two red lines. 8.1.3 Turn the print control switch to the left for display only without printing, and to the right for both display and printing. 8.2 Determination
8.2.1 Place the sample soaked in wetting agent with the mesh surface facing up into the measuring cup, cover the cup mouth, do not touch the electrode, and clamp it. 8.2.2 Press the liquid injection key, and the display screen will display "", and the liquid will slowly flow up and be injected into the cavity on the sample surface from the center hole of the detection cover. 8.2.3 When the liquid is filled and overflows, the liquid injection key pops up and the instrument enters the automatic measurement state. During the measurement process, the display screen always displays the pressure change. When bubbling begins, the instrument stops automatically and displays or prints out the pressure and pore size values ​​at the same time. 8.2.4 When repeating the measurement, just press the reset button and repeat the above two operations to achieve re-measurement. At least 5 valid test data shall be measured for each sample.
9 Result calculation
The maximum (equivalent) pore size Φmax (μm) can be calculated by formula (1): pmax
Where: —
40.8%,· cos6
Surface tension of the wetting agent at the test temperature, mN/mCosine of the angle between the surface tension and the capillary wall; conversion factor;
Air pressure, kPa;
Pressure of the wetting agent on the paper, kPa.
Express the result as its arithmetic mean, accurate to 1 decimal place. Test report
The test report should include the following items:
a) This standard number;
b) Description of the specimen;
c) Test results;
d) Any test conditions that deviate from this standard. (1)
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.