MT 141-2005Plastic net protecting top-plane in coal mining (English PDF)

4.1 Appearance quality

Indicates flame-retardant and anti-electrostatic

Indicates plastic net protecting top-plane

Indicates single cross-section tensile strength, in Megapascal (MPa)

Indicates materials

b) If started time keeping from the time when the sample flame is

extinguished, the arithmetic mean of the flameless combustion time of

the 6 samples shall be less than 10 s, wherein the single value of the

flameless combustion time of any one of the samples shall be less than

30 s.

4.9.2 Alcohol lamp combustion performance

The top-plane protection net shall, through the alcohol lamp combustion test,

comply with the following requirements.

a) After removing the alcohol lamp, the arithmetic mean of the flame

combustion time of the 6 samples shall be less than 6 s, wherein the

single value of the flame combustion time of any one of the samples shall

be less than 12 s.

b) If started time keeping from the time when the sample flame is

extinguished, the arithmetic mean of the flameless combustion time of

the 6 samples shall be less than 10 s, wherein the single value of the

flameless combustion time of any one of the samples shall be less than

30 s.

4.10 Specifications of top-plane protection plastic net

The general specifications of the top-plane protection plastic net are as shown

in Appendix A.

5.1 Sample preparation

After the product was made 24 h, TAKE the sample.

5.2 Appearance quality

CUT one piece of sample having a length of not less than 10 m; PERFORM

visual inspection.

5.3 Specification size inspection

CUT one piece of sample having a length of 1m; USE a Vernier caliper having

a precision of 0.02 mm to measure width at any 5 points along the parallel

direction; TAKE the arithmetic mean; LEAVE 2 places after the decimal point;

ROUND off to 1 place after the decimal point; USE a Vernier caliper having a

precision of 0.02 mm to measure thickness at any 5 points; TAKE the

arithmetic mean; LEAVE 2 places after the decimal point; ROUND off to 1

place after the decimal point.

5.4 Skewness test

c) Respectively CALCULATE the tensile strength and tensile elongation at

fracture of each group of 5 samples, and CALCULATE the arithmetic

mean of the tensile strength and the tensile elongation at fracture of each

group of samples, TAKE the integer.

5.6 Surface resistance test

5.6.1 Sample preparation

5.6.1.1 TAKE a certain number of top-plane protection nets; USE the hot

pressing method to prepare them into circular or square sheet samples the

surface of which is flat and smooth; the sample thickness is (1 ± 0.2) mm, the

sample diameter or edge length is not less than 100 mm, and the number of

sample is 3; AND if the sample surface is coated with conductive layer, it shall

arrange the top-plane protection nets in parallel into square sample, AND

press it flatly before using it as the sample for the measurement of the surface

resistance.

5.6.1.2 USE the clean silk cloth or sterilized cotton cloth which is dampened

with distilled water to clean the sample; then USE a clean dry cloth to wipe the

sample dry; PLACE it in a dry place for over 24 h; before the arbitration test,

PLACE the sample in a dry place for 7 days before making the test.

5.6.1.3 Before the test, PLACE the sample in an environment having a

temperature of (25 ± 5) °C and a relative temperature of 60% ~ 70% for at least

2 h.

5.6.2 Conductive liquid

The composition of the conductive liquid (mass percentage) is.

Anhydrous polyethylene glycol having a molecular weight of 600. 79.9%

Soft soap. 0.1%

Water. 20.0%

5.6.3 Instrument

5.6.3.1 Surface resistance tester.

The measuring range is 103 ~ 1010 ohm, the accuracy is 10%, the DC power

supply voltage range is 50 ~ 500 V, AND the choice of voltage shall be based

on the conditions that the power consumption of the sample does not exceed 1

W.

5.6.3.2 Electrode.

USE a cylindrical coaxial copper pillar and a copper ring to make electrode, the

size of which is as shown in Figure 2. The base surface of the inner electrode

is round, the base surface of the outer electrode is ring, the base surfaces of

length of about 100 mm, OR through the thermometer which complies with the

temperature measurement requirements. When measuring the temperature,

KEEP the bare copper wire at a position 50 mm above the alcohol combustion

nozzle; AND if the bare copper wise can be blown within 6 s, it is deemed as

reaching to the flame temperature.

5.7.3.4 During the test, the sample surrounding air flow shall be minimized, in

order to avoid influencing the flame burning the sample.

5.7.3.5 During the test, the fuel level in the container shall be kept within the

range (600 ± 20) mm away from the alcohol blast burner nozzle, as shown in

Figure 3.

5.7.3.6 During the test, PLACE the sample in the flame to burn it, and

appropriately MOVE the sample to ensure that the relative position between

the sample and the blast burner is always maintained at the testing position as

shown in Figure 3.

5.7.3.7 The sample burning duration in the flame shall be at least 5 s AND at

most 10 s, BUT the flame combustion time of the same group of 6 samples

shall be consistent.

5.7.3.8 During the test, the flame combustion time and flameless combus...

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