| Coal mines are a high incidence area for pneumoconiosis in China,and individual protection is an important tool for effective prevention of pneumoconiosis.However,the current self-absorbing filtered anti-particulate respirator worn by miners,the testing standard is based on the general industrial environment,under the coupling effect of deep high dust,high humidity,high temperature and strong load operation,it is difficult to ensure that its indicators such as filtration efficiency,suction resistance and wearing time still meet the standard requirements.In view of this,this paper comprehensively explores two simple masks(SM-A,SM-B),two N95 anti-particulate respirators(FFR-A,FFR-B),two N95 viscoelastic silicone half masks(EHR-A,EHR-B),a total of six commonly used self-absorbing filtered dust masks/respirators,in the light of questionnaire survey,numerical simulation,simulation experiments,theoretical analysis and other research means.penetration rate,most easily penetrated particle size(MPPS),suction resistance,quality factor(Q_f)and other key performance indicators in deep well high dust,high humidity,high temperature and strong load operating environment.The main conclusions of this thesis are as follows.1)A study of 1498 dust miners in five major mining areas in Xinjiang,Henan,Shandong,Shanxi and Inner Mongolia provinces showed that the main types of dust miners were exposed to were coal dust and silica dust,and 69.23%of miners had dust concentrations exceeding the standard;23.08%of miners had dust exposure times of 5-6 hours,and 38.46%had dust exposure times of 6-8 hours;among the respiratory protective equipment used,48.07%used simple disposable half-masks and 35.34%used viscoelastic silicone half-masks.48.07%of the miners used simple disposable half masks and 35.34%used viscoelastic silicone half masks;more than 50%of the miners were dissatisfied with the performance of the respiratory protective equipment such as tightness,filtration and suction resistance.2)The inspiratory resistance of six self-absorbing filtered masks/respirators was simulated in a deep well simulation environment with 40°C,100%RH and 60mg/m~3coal dust concentration,and it was found that with the increase of coal dust loading time,the inspiratory resistance of each tested mask/respirator increased sharply,and it far exceeded the national maximum allowable limit within 40min.3)Based on the self-absorbing filtered dust mask simulation and testing system constructed independently,the penetration rate test results of six masks/respirators show that(1)the penetration rate of coal dust is greater at a coal dust concentration of20 mg/m~3,100%RH,and 40°C;(2)The penetration rate of coal dust increases with the increase of constant flow rate and decreases with the increase of circulating flow rate;(3)At the flow rate of 30L/min,the penetration rate of masks/respirators in circulating flow mode is higher than that of constant flow rate,and as the flow rate increases to85L/min,the penetration rate of masks/respirators in constant flow mode is higher than that of circulating flow rate.4)The MPPS test results of the six masks/respirators showed that:(1)At a dust concentration of 20 mg/m~3,the MPPS of SM-A and FFR-A changed significantly with increasing test time;the MPPS of SM-B,FFR-B,EHR-A and EHR-B remained at 10-40 nm;(2)At 100%RH,the MPPS of SM-A,SM-B,FFR-A,FFR-B,EHR-A’s MPPS changed significantly with the increase of testing time,and EHR-B’s MPPS stayed at10-20 nm;(3)At 40°C,the MPPS of the six masks/respirators showed significant changes with the increase of testing time,SM-A,SM-B,FFR-A,FFR-B’s MPPS changed significantly with the increase of testing time,EHR-A,MPPS of EHR-B remained at 10-20 nm;(4)With the increase of the test duration at the flow rate of 30L/min,the MPPS of SM-A and SM-B changed significantly,FFR-A showed no significant MPPS,and MPPS of FFR-B,EHR-A,EHR-B remained at 10-20 nm;with the increase of the inspiratory flow rate,the MPPS of each mask/respirator showed obvious changes in MPPS and showed the characteristics of multi-peak distribution of penetration rate;(5)With the increase of test time:the MPPS of EHR-A and EHR-B changed significantly at the circulating flow rate,and the MPPS of SM-A,SM-B,FFR-A and FFR-B remained at 10-30 nm;while at the constant flow rate,the MPPS of SM-A changed significantly,and the SM-B,FFR-A,FFR-B,EHR-A and EHR-B MPPS remained at 10-30 nm.5)The test results of inspiratory resistance of six masks/respirators show that:(1)in high coal dust concentration of 60 mg/m~3,high relative humidity of 100%,and high temperature of 40°C,the inspiratory resistance increases faster with the test time;(2)the inspiratory resistance at constant flow rate is higher and increases faster compared to the circulating flow rate;(3)the inspiratory resistance increases significantly with the increase of the test flow rate.6)The results of the quality factor analysis of the six masks/respirators showed that(1)the Q_f value was higher at a coal dust concentration of 60 mg/m~3,60%RH,and30°C;(2)the Q_f gradually decreased as the test flow rate increased;(3)At a flow rate of 30 L/min,the Q_f in constant flow mode is higher than the circulating flow rate.7)The test results of the six masks/respirators show that:(1)at a coal dust concentration of 20 mg/m~3,the penetration rate of EHR-A is the smallest,the inspiratory resistance of SM-B is the lowest,and the overall performance of SM-B is the best;(2)at 100%RH,the penetration rate of EHR-A is the smallest,the inspiratory resistance of FFR-A is the lowest,and the overall performance of FFR-A is the best;(3)at 40°C,the penetration rate of EHR-B is the smallest,the suction resistance of FFR-A is the lowest,and the overall performance of FFR-B is the best;(4)When the test flow rate is 30 L/min,at constant flow rate,the penetration rate of EHR-B is the smallest,the suction resistance of SM-B is the lowest,and the overall performance of SM-B is the best;at circulating flow rate,the penetration rate of EHR-A is the smallest,the suction resistance of SM-B is the lowest,and the overall performance of SM-B is the best;(5)When the test flow rate is 85 L/min,the penetration rate of EHR-B is the smallest,the suction resistance of FFR-A is the lowest,and the comprehensive performance of EHR-A is the best under the constant flow rate;under the cyclic flow rate,the penetration rate of SM-A is the smallest,the suction resistance of FFR-A is the lowest,and the comprehensive performance of FFR-A is the best.The thesis contains 53 figures,35 charts and 98 references. |
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