GB/T 2951.10 specifies the test methods for the dropping point determination method, oil separation determination method, low temperature brittleness test method, total acid value determination method, corrosion test method, dielectric constant determination method at 23 degrees, DC resistivity determination method at 23 degrees and 00 degrees of filling paste. GB/T 2951.10-1997 General test methods for cable insulation and sheath materials Part 5: Special test methods for filling paste Section 1: Dropping point - Oil separation - Low temperature brittleness - Total acid value - Corrosion - Dielectric constant at 23°C - DC resistivity at 23°C and 100°C GB/T2951.10-1997 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Common test methods for iesulatingand sheathing materials of electric cablesPart 5 : Methods specific to filling compoundsSecllon one: Drop-point .- Separation of oil-Lower temperaturebrittleness—-Total acld number-Absence of corrosive componenisPermittlvity at 23 C—DC resistivity at 23'C and 100C
GB/T 2951. 10 - 1997
idtIFC811-5-1:1990
Common test methods for iesulatingand sheathing materials of electric cablesPart5 : Methods specific to filling compoundsSecllon one: Drop-point .- Separation of oil-Lower temperaturebrittleness—-Total acld number-Absence of corrosive componenisPermittlvity at 23 C—DC resistivity at 23'C and 100C 100℃ 1 Range
GB/T2951.10 specifies the test methods for the dropping point determination method, oil separation determination method, low temperature brittleness test method, total acid value determination method, corrosion test method, dielectric constant determination method at 23℃, DC resistivity determination method at 23℃ and 100℃ of filling paste. 2 Test principles
Any test requirements specified in this standard can be modified in the relevant cable product standards to meet the needs of special types of cables. 3 Applicable range
The test conditions and test parameters specified in this standard are applicable to the filling materials in communication cables. 4 Dropping point
Note; The purpose of this test is only for classification,
4.1 Overview
The dropping point test can be used to determine the maximum temperature that a filling paste can withstand without complete liquefaction or excessive oil separation. 4.2 Method A (reference method)
4.2.1 Test equipment
a chrome-plated brass cup, the dimensions of which are shown in Figure 1; a heat-resistant glass test tube with three grooves inside to support the chrome-plated brass cup, the dimensions of which are shown in Figure 2: a thermometer, graduated in degrees Celsius, with an accuracy of 1°C and a temperature measuring range of -5 to 300°C. The mercury ball is 10 to 15 mm long and 5 to 6 mm in diameter (the immersed part is 76 mm); an oil bath consisting of 400 ml of burner and appropriate amount of oil, a ring frame and a ring to support the oil bath, a thermometer, two cork plugs as shown in Figure 2, a polished metal rod with a diameter of 1.2 to 1.6 mm and a length of 150 mm, and a suitable device for heating and stirring the oil bath. 4.2+2 Test steps
Insert a thermometer in the cork as shown in Figure 2, adjust the position of the upper cork so that the bottom end of the temperature probe is 3mm above the bottom of the cup, and install the instrument for the test. Hang the second thermometer in the oil bath so that its temperature probe is roughly on the same level as the temperature probe of the thermometer in the test tube.
Fill the filling paste into the large mouth of the chrome-plated brass cup until it is full. Take care to avoid moving the filling paste and scrape off the excess filling paste. The cup should be placed vertically with its small part facing down. Gently press the metal rod so that it extends about 25mm above the large part. Press the metal in the water direction of the cup so that it contacts the upper and lower edges of the cup. Keeping this state, rotate the cup around its axis and at the same time let the cup fall along the metal drop until it passes through the lower end of the metal drop. This explosive swirling motion will cause the filling paste to adhere to the metal rod, leaving a conical cavity in the cup and a reproducible geometric filling sound in the cup. Place the brass cup and thermometer in a test tube and suspend the test tube in an oil bath with the oil level no more than 6 mm from the edge of the test tube. If the cork holding the overflow meter in the test tube is properly adjusted, the 76 mm immersion mark on the thermometer will be flush with the bottom edge of the cork. The assembled test piece should be flooded to this point.
Stir the oil bath and heat at a rate of 4 to 7 K/min. Reduce the heating rate until the oil bath temperature is about 17C below the expected dropping point of the filling paste, so that the test arm temperature is 2°C below the oil temperature before the oil bath overflow increases by another 2.5K. Continue to heat the oil bath at a rate that keeps the temperature of the test tube and the oil bath temperature 1 to 2°C different. This requirement is achieved when the oil is heated at a rate of about 1 to 1.5 K/min. As the temperature increases, the filling paste will gradually flow out of the small hole in the cup. When the first drop of the sample drips, record the temperature values ​​of the two thermometers.
4.2.3 Evaluation of test results
The average value of the temperature values ​​of the two thermometers is the dropping point of the filling paste. 4.3 Method B
4.3.1 Test equipment
A chrome-plated yellow feather cup that meets the size shown in Figure 3. The cup can also be made of other suitable metals that are not affected by the filling being tested. The openings at the top of the cup and the bottom of the test tube should be smooth, parallel to each other, and perpendicular to the axis of the cup. The lower part of the large part of the cup is approximately hemispherical and has a certain internal depth, so that when a steel ball with a diameter of 7.0 mm is placed in the cup, the top of the steel ball is (12.2±0.15) mm away from the bottom opening of the test tube. The bottom edge of the opening should have no grooves or rounded corners. A cylindrical metal sleeve for fixing the overflow meter and a metal box screwed to the metal sleeve, the dimensions of which are shown in Figures 4 and 5. The metal sleeve is fixed to the temperature connection so that after the metal box is screwed onto the metal sleeve, the bottom of the temperature measuring head of the thermometer is (8.0 ± 0.1) mm below the stop ring. The thermometer rod is coaxial with the metal sleeve and the metal box. The thermometer is fixed to the metal sleeve with cement suitable for its temperature range. The thermometer is graduated in degrees Celsius, ranging from 20 to 120°C, with a scale accuracy of 1°C. The maximum length of the temperature measuring head is 6 mm. The diameter is 3.35 to 3.65 mm (the immersed part is 100 mm). Heat-resistant glass test tube, length (110 ± 2) mm, inner diameter (25 ± 1) mml. A beaker large enough to allow the test tube to be vertically immersed in the heating medium for two-thirds of its length and 251 from the bottom of the beaker. Stir with a stirrer to ensure that the temperature of the oil bath is uniform. Clamp the test tube and the oil bath thermometer with the sample holder and support the beaker on the heating source, the gas torch, which can heat the liquid bath at a certain rate. Note: For filling pastes with a dropping point below 80°C, water is recommended as the heating medium; for filling pastes with a dropping point above 80°C, glycerin or light oil is recommended as the heating medium.
4.3.2 Test steps
Fill the brass cup with the filling paste with a scraper and scrape off the excess, carefully remove the bubbles, but do not melt the filling, push the cup into the metal box until it cannot move, avoid lateral movement, and scrape off the excess filling squeezed out from the bottom of the cup. Be careful not to block the small support on the side of the metal box. Install the thermometer and the matching brass cup, so that it is in the center of the test tube. Pass through the center hole of the wooden stopper with side teeth, so that the bottom of the brass cup is higher than the bottom of the test tube (25 ± 1.0). Then, place the test tube vertically in the beaker GB/T 2951. 10-1997 containing liquid heating medium, so that two-thirds of its length is immersed, and the bottom of the test tube should be 25mm higher than the bottom of the beaker, as shown in Figure 6. Heat the liquid and stir it continuously. When the temperature is 20℃ below the dropping point of the sample, use the dropping point thermometer to indicate the temperature rise at a rate of 1K/min, and record the temperature when the first drop of sample drips from the cup, regardless of its composition. Or record the temperature when a continuous fluid reaches the bottom of the test tube.
4.3.3 Evaluation of test results
The temperature recorded by the dropping point thermometer is the dropping point next to the filling, accurate to 1.0℃. 5 Oil separation
5.1 Overview
This test is used to determine the amount of oil separation at 50°C. 5.2 Test equipment
The rectangular box consists of two rectangular boxes, the dimensions of which are shown in Figure 7. The surface finish of the machined surface is required to ensure that the separated oil will not be blocked when flowing.
5.3 Test steps
Heat the filling paste to a transparent state and stir it evenly. Fill one box in the rectangular box with the molten filling sound. Then put it in an oven preheated to 100°C, then open the oven door and cool it to room temperature. After cooling for at least 24 hours, turn the rectangular box 90 degrees, and then heat the oven to (50±2)°C and keep it for 24 hours. After heating, take out the rectangular box from the oven for testing.
5.4 Test result evaluation
The separated oil should not extend beyond the 5mm center of the right-angle box without the filling paste (excluding the oil seepage along the edge of the box).
6 Low-profile
6.1 Overview
This test is used to check the adhesion between the filler and other components of the electrode. Note: This method is not suitable for filler pastes with a dropping point higher than 80°. 6.2 Test equipment
Aluminum alloy sheet with dimensions of 170 mm × 14 mm × 0.9 mm. Brass template with dimensions of 160 mm × 160 mm × 1 mm, with a rectangular opening of 100 mm × 10 mm and a positioning edge to prevent the lead sheet from moving.
6.3 Test procedure
Clean each lead alloy sheet with a wire brush and place it on a flat bottom plate. Then place the brass template on the lead alloy sheet so that it symmetrically covers the longitudinal edges of the lead alloy sheet. Scrape the filler paste to the opening of the brass template at room temperature. Scrape off the excess filler paste with a hot scraper or other suitable tool, and then remove the brass template. Prepare ten test strips in the same way as above.
The specimens are placed at room temperature for 16 h and then cooled to (-10 ± 1) °C for at least 1 h. Each specimen shall be immediately wound in a spiral around a metal test mandrel fixed in a horizontal position. The diameter of the metal test mandrel is 10 mm and has been precooled to -10 °C. The winding rate is about one turn per second. Each specimen shall be checked for cracks with normal or corrected vision without a magnifying glass. 6.4 Evaluation of test results
No more than 2 specimens out of 10 specimens shall have cracks. If more than 2 specimens fail, the test shall be repeated. Note that slight detachment of the filler corners is permitted. 7 Acid value
7.1 Overview
CB/T 2951.10—1997
This test is used to test the corrosive components next to the filler. The total acid value is defined as the amount of potassium hydroxide (KOHI) required to titrate all the acid components in 1 g of the sample, in mg. 7.2 Test Equipment
One 50 mL burette with a minimum scale of 0.1 mL or one 10 mL burette with a minimum scale of 0.05 mL. 7.3 Reagents
Reagents should be of confirmed analytical grade. Distilled water should be used throughout the procedure. 7.3.1 Potassium Nitrogen Oxide Standard Solution in Anhydrous Isopropyl Alcohol (0.1 N) Add 6 g of solid KOH to a conical flask containing about 1 L of anhydrous isopropyl alcohol (water content less than 0.9%). Boil the solution slowly for 10 to 15 min, stirring constantly to prevent KOH from caking at the bottom of the flask. Add at least 2 g of sodium hydroxide (BaOH), and boil the solution slowly for another 5 to 10 min. Cool to room temperature and let stand for several hours. Then filter the supernatant using a fine sintered glass or porcelain funnel. Avoid excessive exposure of the solution to carbon dioxide during filtration. Place the test solution in a chemically resistant reagent bottle, away from corks, rubber or saponifiable lubricants, and protect it with a protective sleeve containing soda ash, lime or alkaline cotton. The test wave should be sufficient for multiple calibrations. It is best to use phenolic acid to determine the endpoint. Titrate 100 mL of pure potassium phthalate in 100 mL of CO2-free water so that a change of 0.0005 N can be detected. Note
1 To simplify calculations, the standard KOH solution can be adjusted so that 1.0 mL. is equivalent to 5.00 mg KOH. 2NeOH can be substituted for KOH
7.3.2 p-Naphtholbenzein indicator solution Dissolve 10 g/L p-naphtholbenzein in the titration solution specified in 7.3.3. p-naphtholbenzein should comply with the provisions of Appendix A.
7.3.3 Titration
Add 500tmL toluene and 5mL water to 495mL anhydrous isopropanol. 7.4 Test Procedure
Add about 25g of the filling sample (weighed to the nearest 0.1g) to a 250nL conical flask, add 100mL titration solution and 0.5mL indicator solution, and shake continuously to dissolve the sample completely in the titration solution. Titrate immediately at a temperature below 30°C. Gradually add 0.1V KOH solution, and shake as much as possible to disperse the KOH. When approaching the endpoint, shake the flask vigorously, but avoid dissolving carbon dioxide (CO,) in the titration solution.
When the solution changes color for 15s or the color can be reversed by adding two 0.1N HCl, the titration endpoint is considered to have been reached. Note: When the filling solution changes from orange to green or green, the titration endpoint is considered to have been reached. Carry out a blank titration. Add 0.1N KOH solution in increments of 0.05mL or 0.1mL to 100mL of titration solution and 0.5mL of indicator solution. Record the amount of 0.1N KOH solution required to reach the end point (change from orange to green). 7.5 Calculation
Total acid value is calculated as follows:
Total acid value, mg KOH required per gram solution = (4-.B)N×56.1W
Where: A—KOH required for titration sample, mL;—KOH required for blank titration, mL
N—KOH solution equivalent concentration;
W—grams of sample used.
B Abrasiveness
8.1 Overview
GB/T 2951.10---1997
This method is used to indicate the effect of fillers when they come into contact with the metal parts of cables. 8.2 Test equipment
A lead strip not less than 0.5 mm thick and with a purity of at least 99.5% is cut into small pieces of 50 mm long and 20 mm wide; a cold-rolled tungsten steel strip not less than 0.5 mm thick is cut into small pieces of 50 mm long and 20 mm wide. Note: There are two grades of copper commonly used: high-conductivity toughened steel, phosphating reduced copper and oxidized high-conductivity copper, and the results are similar. 8.3 Test procedure
Polish the copper strip on both sides to obtain a uniform and smooth surface without defects. Wash the strip with ether and let it dry. Use a clean rod for further operation.
Place about 120 g of fill preheated at (80 ± 2)°C in a tall glass beaker with a capacity of at least 200 ml. Fill the prepared aluminum and copper strips completely with the fill paste. The gold strips should not touch each other or the walls of the beaker. Then place the beaker in an oven at (80 ± 2)°C for 14 days.
After the beaker has been in the oven for the specified time, remove it and allow it to cool to room temperature. Remove the metal sheet, wipe off any excess filler and clean it first with petroleum ether and then with ether.
Use normal or corrected vision without a magnifying glass to examine the surface of the metal sheet for corrosion, rust or discoloration. 8.4 Evaluation of test results
The metal sheet shall show no corrosion.
Dielectric band number at 923°C
9.1 Overview
This test is used to determine the relative dielectric constant of the filler paste. This test method shall be consistent with the three-electrode test cup test method specified in IEC 247. 9.2 Supplement to IEC 247 method
Heat the filler paste to the transparent point and pour it into an electrode cup that has been preheated to the same temperature, taking care to avoid air bubbles entering the electrodes. The test shall be carried out at (23 ± 2)°C. DC resistivity at 1023°C and 100°C
10.1 Overview
This test is used to determine the DC resistivity of the filler within a certain temperature range. This test method shall be consistent with the three-electrode test method specified in IEC 247. 10.2 Supplement to IEC 247 method
The filler shall be filled in accordance with the method in 9.2.
The test shall be carried out at (23±2)°C and (100±3)°C: the test voltage shall be 100 V DC.
Size 4
Internal diameter 0.4
Inner diameter 4.5/4.7
GB/T 2951. 10 -1997
Figure 1 Cup
Flowmeter
Ventilation type
11. 1/12. 7
Sharp edge only with deburring
Soft guide plug and test tube enzyme 1. 5
, Renlai test tube
Three equally divided brass cups
Figure 2 Instrument assembly diagram
Dimension unit: mm
Dimension unit: mm
.5/5.5
47.35/7.65
GB/T 2951. 10—1997
Said edge only with deburring
7.00 Roller
Dimension unit: mm
Figure 3 Cup
G. C / 1G. 2
Agitator,
Steel nail or 12B screw
5. 5/4. 7
Figure 5 Metal box
No light line
Figure 6 Instrument assembly drawing
M10X10
Dimension unit: mm
Figure 4 Thermometer and metal sleeve
0. 02/ G. 03
Dimension unit: mm
GB/T 2951.10—1997
Figure 7 Right-angle box with two vertical boxes
Dimensions: mm
A1 Appearance
Para-naphthobenzene should be a red amorphous powder. A2 Amide
Chloride content should be less than 0.5%.
A3 Solubility
GB/T 2951. 10—1997www.bzxz.net
Appendix A
(Indicative Appendix)
Technical Specifications for Para-naphthobenzene
10 g para-naphthobenzene should be completely dissolved in 1 L of titration solution specified in 7.3.3. A4 Minimum absorption coefficient
Dissolve 0.1000 g of sample in 250 mL of methanol and dilute 5 mL of the solution to 100 mL with a buffer having a pH value of 12. This final dilution shall be read on a Beckmann DU or other alternative spectrophotometer with a 1 cm sample cup and water as a blank sample at 6.50 m. The minimum absorbance shall be 1.20. A5p Range
When tested using the pH range method for the p-benzoin indicator specified in 7.3.2, the indicator shall turn a clear green color at a pH of 11 ± 0.5.
The addition of not more than 0.5 mL of 0.01 N KOH1 to the blank sample shall cause the indicator solution to turn a clear green color. The addition of not more than 1.0 mL of 0.01 N KOH1 to the blank sample shall cause the indicator solution to turn blue. The initial pH of the indicator solution shall be at least as high as that of the blank sample.
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