GB/T 4925-1985 Test method for breaking strength and breaking elongation of synthetic fiber fishing nets GB/T4925-1985 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
GB4925-85
Testing method f-or breaking load and elongation of netting of synthetic fibre
Promulgated on 1985-02-02
State Administration of Technical Supervision
Implementation on 1985-09-01
National Standard of the People's Republic of China
Testing method f-or breaking load and elongation of netting of synthetic fibre
GB4925—85
This standard specifies the test method for the breaking strength, tearing strength, mesh breaking strength and elongation of netting of synthetic fibre fishing nets.
1 Explanation of terms
1.1 Dry specimen: Place the specimen in a test room with standard atmospheric conditions (temperature above 20 ± 2°C, the specimen is a dry specimen.
Relative humidity 63-67%), and balance for 24 hours
1.2 Wet specimen: Place the specimen in water with a temperature of 20 ± 2°C and immerse it for more than 24 hours, the specimen is a wet specimen, 1.3 Longitudinal direction of the mesh: the warp direction of the mesh. 1.4 Transverse direction of the mesh: the weft direction interlaced with the warp 1.5 Longitudinal direction of the plain mesh: the warp direction of the mesh. 1.6 Transverse direction of the plain mesh: the weft direction of the mesh 2 Test items
2.1 Mesh breaking strength and elongation at break
a. Dry longitudinal breaking strength and elongation at break of the mesh. b. Wet longitudinal breaking strength and elongation at break of the mesh. c. Mesh transverse dry breaking strength and breaking elongation. d. Mesh transverse wet breaking strength and breaking elongation bzw.cn
2.2 Breaking strength and breaking elongation of plug-in mesh and plain woven mesh a. Mesh longitudinal dry breaking strength and breaking elongation. b. Mesh longitudinal wet breaking strength and breaking elongation. c. Mesh transverse dry breaking strength and breaking elongation. d. Mesh transverse wet breaking strength and breaking elongation 2.3 Mesh tearing strength
a. Mesh longitudinal dry tearing strength.
b. Mesh longitudinal wet tearing strength.
c. Mesh transverse dry tearing strength. bzxZ.net
d. Mesh transverse wet tearing strength.
2.4 Mesh breaking strength
a. Mesh dry breaking strength.
b. Wet breaking strength of mesh.
3 Test conditions
3.1 The standard atmospheric conditions of the test room are 20±2℃ and the relative humidity is 63~67%. 3.2 Use a constant rate of elongation or constant rate of tension strength testing machine, and have an elongation measuring device. The error of the indicated value shall not exceed 1%. 3.3 The average breaking time of the sample is 20±3s. 3.4 The clamp used for measuring mesh samples shall adopt a flat clamp with an effective width of more than 50mm. It is allowed to add padding to the clamping surface of the clamp to avoid sample clamping or slippage. The measured value of the sample breaking at the clamp shall not be calculated. 3.5 The pre-tension value of the mesh sample, the pre-tension value on each mesh foot of the dry sample is equal to the dead weight of the mesh line of 250±25m in length, and the pre-tension value on each mesh foot of the wet sample is equal to the dead weight of the mesh line of 125±12.5m in length. 4 Sampling and sample processing
4.1 The sample must be taken at a distance of more than 5 meters from the edge of the mesh. 4.2 The sample should be cut away from the mesh knot or connection point, and the mesh foot should be processed by melting method. 4.3 The sample should be taken from various parts of the mesh. When testing the same item, continuous sampling in the direction where the sample is stretched is not allowed. However, when cutting dry and wet samples at the same time, two samples must be cut continuously in the direction where the sample is stretched. 4.4 The sample must meet the requirements of dry or wet state. 5 Test method
5.1 Breaking strength and elongation at break of mesh
The maximum strength value when the sample is stretched to break is called the breaking strength, expressed in Newton (N) or kilogram-force (kgf). At the same time, the percentage of the stretched length of the sample at break to the original length is the breaking elongation. 5.1.1 Longitudinal dry breaking strength and breaking elongation of mesh 5.1.1.1 Specimen specifications: The effective length of the specimen between the clamps is 200mm, and the width is 4.5 mesh, see Figure 1. For meshes with a mesh length greater than 150mm, the net knot strength shall be tested in accordance with 3.5 of SC110-83 "Test Methods for Synthetic Fiber Fishing Net Lines". 502
5.1.1.2 Test method: Clamp one longitudinal end of the longitudinal dry specimen of the mesh flatly into the upper clamp, and make the mesh feet tight to each other. After pre-tensioning the lower end of the specimen, clamp it into the lower clamp, and then conduct the test to measure the breaking strength and breaking elongation. The number of measurements shall not be less than 10 times. 5.1.2 Wet longitudinal breaking strength and breaking elongation of mesh 5.1.2.1 Specimen specifications: Same as 5.111
5.1.2.2 Test method: The wet longitudinal test specimen of mesh shall be tested in the same manner as 5.1.1.2 5.1.3 Dry transverse breaking strength and breaking elongation of mesh 5.1.3.1 Specimen specifications: Same as 5.1.1.1. D
5.1.3.2 Test method: Clamp one transverse end of the dry transverse test specimen of mesh flatly into the upper fixture, and make the mesh feet close to each other. After pre-tensioning the lower end of the specimen, clamp it into the lower fixture, and then conduct the test to measure the breaking strength and breaking elongation. The number of measurements shall be not less than 10 times. 5.1.4 Transverse wet breaking strength and breaking elongation of mesh 5.1.4.1 Sample specifications: Same as 5.1.1.
5.1.4.2 Test method: The transverse wet sample of mesh is tested in the same way as 5.1.3.2. 5.2 Breaking strength and breaking elongation of twisted and plain woven mesh 5.2.1 Longitudinal dry breaking strength and breaking elongation of mesh 5.2.1.1 Sample specifications: The effective length of the sample between the clamps is 200mm and the width is 50m 5.2.1.2 Test method: Same as 5.1.1.2. 5.2.2 Longitudinal wet breaking strength and breaking elongation of mesh 5.2.2.1 Sample specifications: Same as 5.2.1.1. 5.2.2.2 Test method: The longitudinal wet sample of mesh is tested in the same way as 5.1.1.2. 5.2.3 Transverse dry breaking strength and elongation of mesh 5.2.3.1 Sample specifications: Same as 5.2.1.1. 5.2.3.2 Test method: The transverse dry test sample of mesh shall be tested in the same way as 5.1.3.2. 5.2.4 Transverse wet breaking strength and elongation of mesh 5.2.4.1 Sample specifications: Same as 5.2.1.1. 5.2.4.2 Test method: The transverse wet test sample of mesh shall be tested in the same way as 5.1.3.2. 5.3 Tearing strength of mesh
The maximum strength value when all the knots or connecting points retained on the sample are torn apart shall be expressed in Newton (N) or kilogram-force (kgf). 5.3.1 Dry tear strength of mesh in longitudinal direction
5.3.1.1 Specimen specification: The number of mesh in transverse direction of the specimen shall be not less than 9. Cut the mesh in longitudinal direction from the central mesh at one transverse end, leaving 4 mesh (as shown in Figure 2A1).
5.3.1.2 Test method: Clamp the specimen into the upper and lower clamps as shown in Figure 2B. Measure the maximum strength until all the knots (or connecting points) are torn apart, and the number of measurements shall be not less than 10 times. Longitudinal direction
5.3.2 Wet tear strength of mesh in longitudinal direction
5.3.2.1 Specimen specification: Same as 5.3.1.1. Figure 2
5.3.2.2 Test method: Test the wet specimen in longitudinal direction of the mesh in the same way as 5.3.1.2. 5.3.3 Transverse dry tear strength of mesh
5.3.3.1 Sample specifications: The number of meshes in the longitudinal direction of the sample is not less than 9. Cut the mesh in the transverse direction from the central mesh at one end of the longitudinal direction, leaving 4 meshes.
5.3.3.2 Test method: Test the transverse dry sample of the mesh in the same way as 5.3.1.2. 5.3.4 Transverse wet tear strength of mesh
5.3.4.1 Sample specifications: Same as 5.3.3.1. 5.3.4.2 Test method: Test the transverse wet sample of the mesh in the same way as 5.3.1.2. 5.4 Mesh breaking strength
The maximum strength value when a single mesh is stretched to break, expressed in Newton (N) or kilogram-force (kgf). 5.4.1 Mesh breaking strength
5.4.1.1 Sample specifications: Single mesh. When the mesh length is less than 15mm, a 3×3 mesh sample can be cut and the central mesh can be used as a single mesh for testing.
5.4.1.2 Test method: Hook a single mesh dry sample into a steel hook for testing (as shown in Figure 3A). When the mesh length is too small and the hook cannot be hooked into the net, the mesh can be connected with a mesh wire of the same material and appropriate thickness (as shown in Figure 3B) and then tested. During the measurement, the test is invalid if the net knot is loose, the wire head slips off or does not break at the net knot. The number of measurements shall not be less than 20 times. Figure 3
5.4.2 Wet breaking strength of mesh
5.4.2.1 Sample specifications: Same as 5.4.1.1. 5.4.2.2 Test method: Test the wet mesh sample in the same way as 5.3.1.2. 6 Data processing and result expression
6.1 The data of each item are expressed as the arithmetic mean of the measured values, with three significant figures, and are processed according to the digital rounding rules. 6.2 The measured value should be calculated for unevenness, and the calculation formula is as follows: , = 2-100%
In the formula: H—unevenness;
X—arithmetic mean of all test data: 1—arithmetic mean of each number less than x; total number of data with values ​​less than x;
total number of test data.
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