1. The dust tester should be able to use the instrument to measure the dust concentration and propose measures to control the dust.

2. Carefully check the dust measuring instrument to make the surface clean and complete. The cable or the placing button is sensitive and reliable. When using the photoelectric dust detector, check the battery voltage. When the voltage is lower than the voltage, it should be charged as required.

3. Prepare the instrument, tools and accessories according to the dust measurement location and sampling quantity of the class.

4. When using the dust sampler to measure dust, the sampling filter should be carefully weighed beforehand. When measuring, use the plastic tweezers to remove the lining paper on both sides of the filter, then put the filter on the analytical balance for weighing, and record the weight value, edit the number, put it in the filter box; use the photoelectric dust meter When measuring dust, have enough filter paper tape.

5. When going down the well, you should bring all the instruments and meters. The instruments should be carried with you. It is strictly forbidden to squeeze and not allow others to take it or play with them.

6, pay attention to the observation of the top of the sampling site, transportation and so on. In order to ensure the safety of the work, if there are hidden dangers, it must be dealt with first.

7, dust sampler operation

(1) Before sampling, first adjust the required flow rate (generally 15~30L/min), and check to ensure no air leakage, then take out the prepared filter clamp and fix it on the sampler.

(2) When sampling, it should be noted that the flow rate is stable, and the length of the sampling time is determined according to the estimated dust weight on the filter (generally 1 to 120 mg, but not less than 1 mg). Record the sampling location, work process, sample number, flow rate and dust prevention measures in detail, and note the sampling start and end time.

The sampling time can be calculated as follows

T=1000W/CQ (1)

Where T is the sampling time, min;

W——the weight that the dust should reach, mg;

C——the dust concentration of the expected working surface, mg/m3;

Q——Flow at sampling, L/min.

After sampling, remove the filter retaining ring, quickly put it into the sampling box and ask the dust to face up, do not shake, vibrate, and then bring it back to the laboratory for weighing analysis.

(3) After sampling, the filter should be placed in a desiccator for drying for 1 hour, and then weighed; if there is water mist on the sampling site or if there is water droplet on the surface of the filter, the humidity is too large, the filter should be placed first. Dry in a drying oven at 60-65 ° C for 2 h, then dry in a desiccator for 30 min, and finally place it on the analytical balance and weigh it once until constant weight. The weigh should be recorded.

(4) Dust concentration at the dust measurement site is calculated according to formula (2):

C=1000 (W2-W1)/QT (2)

Where C is the concentration of dust in the air, mg/m3;

W2——the weight of the filter after sampling, mg;

W1——the weight of the filter before sampling, mg;

Q——Flow at sampling, L/min;

T - sampling time, min.

The dust concentration deviation of the two parallel samples does not exceed 20%, which is an effective sample, and the average of the two is taken as the dust concentration at the place of use.

The deviation rate of two parallel products is calculated according to formula (3):

f=×100% (3)

The deviation rate of two parallel samples in the formula, %;

a, b - dust concentration of two parallel samples, mg/m3

The weighing interval of the filter before and after sampling should be shortened as much as possible to avoid affecting the accuracy of the measurement results.

(4) When there is oil mist in the air at the sampling location, the filter membrane should be degreased first. The specific steps are as follows:

Place the steam bottle containing 120# solvent gasoline in the crucible with the thermometer with the range of 200 °C, connect the condensing device and the electric furnace, keep the oil temperature at about 110 °C, the maximum is no more than 120 °C, and use a wide range of cleaning. The mouth bottle collects the distilled gasoline.

Number the three weighing bottles and enter the distilled number 120# solvent gasoline.

The oil mist filter was folded in half by tweezers, and then the folded filter edge was clamped in the No. 1 weighing bottle with a vascular clamp for 2 min, and then placed in a No. 2 weighing bottle for 2 min.

Place the oil-removed filter on a clean glass plate, open the filter with tweezers, let the gasoline evaporate, and weigh it after 30 minutes.

The filter with the oil removed once was placed in the third weighing bottle in the above manner, and then the oil was removed once, and then left to stand for 30 minutes, the gasoline on the filter was volatilized, and then weighed until constant weight.

8. Operation of photoelectric dust meter

(1) Calibrate the sampling flow and sampling time of the instrument and adjust according to the instructions of the instrument.

(2) The number of consecutive measurements of each dust measurement site is not less than 3, and the average value is taken.

(3) When measuring the dust concentration with the fast direct reading dust meter, the measured data must be converted according to the concentration of the dust sampler.

9, dust control precautions

(1) Pay attention to the following problems when selecting the dust measurement position;

a. The sampling location is located on the return air side;

b. Take the height of the person's breathing zone, usually about 1.5 meters;

c. When sampling the heading face, the side of the roadway where the air duct is not installed shall be taken 4-5 meters away from the place of rock ( coal ), eye picking or shotcreting.

d. When sampling on the mechanized coal mining face, it should be carried out on the return side of the shearer and 10~15m away from the shearer.

e. When working in multiple stages of coal mining face, it should be sampled at 10~15m from the return air inlet of the working face.

f. When sampling at the transfer point, it should be carried out at the return air side at a distance of 3m from the transfer point.

g. When sampling in other dusty places, the sampling site should be as close as possible to the breathing zone operated by the worker, without prejudice to the operation of the worker.

(2) When measuring dust, the sampling port of the instrument must meet the wind flow.

(3) The requirements for the dust start time are: for continuous dust production, sampling should be carried out after the production reaches the sinking state for 5 minutes; for intermittent dust production, it should be sampled during the worker's operation.

(4) It is necessary to fill in the dust record of each time in time.

(5) After the dust measurement is completed, the dust determination result report form should be filled out, and the dust dust concentration measurement report form of this month should be completed at the end of the month and reported in time.

(6) When using the dust sampler to measure dust, if the filtered membrane is contaminated or the dust is lost, it should be discarded and resampled; since the membrane is not resistant to high temperature, it should not be used at the sampling site above 55 °C.

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