This standard specifies the method for determining hydrogen sulfide using a longer hydrogen sulfide detector tube. This standard is applicable to the determination of the concentration of hydrogen sulfide in mine air (or gas). Note: The concentration of hydrogen sulfide is expressed in ppm (V/V), 1 ppm = 0.0001%. MT 277-1994 Method for determining harmful gas hydrogen sulfide in mine air (detection tube method) MT277-1994 Standard download decompression password: www.bzxz.net

Coal Industry Standard of the People's Republic of China
Harmful Gases in Mine Air
Method for Determination of Hydrogen Sulfide (Detector Tube Method)
Subject Content and Scope of Application
This standard specifies the method for determining hydrogen sulfide using a longer hydrogen sulfide detector tube. This standard is applicable to the determination of the concentration of hydrogen sulfide in mine air (or gas). Note: The concentration of hydrogen sulfide is expressed in ppm (V/V), 1ppm0.0001%. 2 Principle
MT 277-94
When the mine air (or gas) containing hydrogen sulfide passes through the indicator powder made of lead acetate solution adsorbed by a carrier, the indicator powder changes from white to brown, and the length of the color change column indicates the concentration of hydrogen sulfide. 3 Apparatus
3.1 Detector Tube
3.1.1 The detector tube consists of a glass tube, indicator powder, an isolation layer and a lining plug (see Figure 1). 5
Figure 1 Schematic diagram of the longer hydrogen sulfide detection tube
1—Starting end lining plug; 2—Isolation layer; 3-Indicator powder: 4—Division line: 5—Glass tube? 6—Lining plug
3.1.2 The detection tube must be a product produced by a unit with a production license for manufacturing measuring instruments. 3.1.3 The detection tube must have a product quality certificate and a safety mark (MA). 3.1.4 Specifications of the detection tube
Measuring range: 3~100ppm.
Minimum division value: 5ppm.
Minimum detection concentration: 3.0ppm.
3.2 Samplerwww.bzxz.net
3.2.1 There are three types of samplers: round-shaped suction type (see Figure 2A), round-shaped vacuum type (see Figure 2B) and bellows type (see Figure 2C). Approved by the Ministry of Energy of the People's Republic of China on May 1, 1992 and implemented on October 1, 1994
MT 277-94
Figure 2 Schematic diagram of sampler
A-circular simple suction type; B-circular simple vacuum type; C-accordion type3.2.2 The sampler must be a product produced by a unit with a production license for manufacturing measuring instruments. 3.2.3 The sampler must have a product quality certificate and a safety mark (MA). 3.2.4 The nominal volume of the sampler is 50mL or 100mL. C
3.2.5 The sampler used in the measurement must have the same performance as the sampler used by the test tube manufacturer to calibrate the test tube. 4 Preparation before measurement
4.1 Airtightness check of the sampler
Take an unopened test tube, plug the air inlet of the sampler, operate the sampler to sample and start timing, and then calculate the leakage rate based on the volume of gas inhaled and the sampling time. The leakage per minute shall not exceed 3% of its volume. 4.2 Appearance inspection of the detection tube
Before using the detection tube, the appearance inspection shall be carried out. If the tip of the tube is broken, the reagent is loose, mixed, discolored, the graduation line is unclear, and the interface between the indicator powder and the isolation layer does not coincide with the zero mark, it shall not be used. 5 Determination steps
5.1 Operation method
5.1.1 Operation method of circular simple suction sampler Open both ends of the detection tube, connect the upper end to the sampler, and evenly extract 100mL of gas sample through the detection tube within 100s. Read the hydrogen sulfide concentration in the measured air (or gas) according to the length of the color change column of the detection tube. 5.1.2 Operation method of circular simple vacuum sampler Break both ends of the detection tube in the cutting hole of the sampler, then insert the detection tube into the air inlet of the sampler, and turn the handle so that the red triangle on the handle corresponds to the red engraved line on the rear end cover of the sampler. Pull open the handle, and after about 2 minutes, when the front end of the color-changing column of the detection tube no longer moves forward, read the concentration of hydrogen sulfide in the measured air (or gas) according to the length of the color-changing column of the detection tube. 5.1.3 Operation method of accordion sampler
Open both ends of the detection tube, connect the upper end to the sampler, then compress the sampler by hand to discharge the gas in it and then release the sampler. After the control chain on the sampler is straightened, start counting the time, and remove the detection tube after about 30 seconds. Read the concentration of hydrogen sulfide in the measured air (or gas) according to the length of the color-changing column of the detection tube. 5.2 Reading of measured values ​​
When the cross section of the color-changing column of the detection tube is neat, the graduation position of the interface between the color-changing part and the non-color-changing part is the concentration of hydrogen sulfide in the measured air (or gas); when the cross section of the color-changing column is not neat, that is, there is an inclined surface, convex or concave shape, the highest and lowest values ​​should be taken according to the graduation position of the color-changing column and averaged.
6 Number of measurements and handling of measurement nests
6.1 When the concentration of the measured gas is relatively stable, perform two measurements. When the allowable difference of the two measurement values ​​meets the requirements of Table 1, take the arithmetic mean as the measurement result. When it does not meet the requirements of Table 1, a third measurement should be performed. When the range of the three measurements (the difference between the maximum and minimum values) does not exceed 1.2 times the allowable difference, the arithmetic average of the three measurement values ​​shall be taken as the measurement result; if the range of the three measurements exceeds 1.2 times the allowable difference, additional measurements shall be performed. The measurement average value is calculated to one decimal place, and after rounding, the integer is reported. Table 1
Measured concentration
6.2 When the concentration of the measured gas is unstable and multiple measurements are performed, the highest value shall be taken. Additional notes:
This standard was proposed by China Coal Research Institute. This standard is under the jurisdiction of Fushun Branch of China Coal Research Institute. This standard was jointly drafted by Fushun Branch of China Coal Research Institute and Hebi Mining Bureau. The main drafters of this standard are Yang Wenzheng, Chen Xingye, and Ye Zhanying. This standard was entrusted to Fushun Branch of China Coal Research Institute for interpretation.
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