Experimental study on protective performance of positive pressure bio-protective hoods
OBJECTIVE To evaluate the protective effect of typical electric air supply positive pressure bio-protec-tive hood(PPBH)on bioaerosol and physical aerosol.METHODS The air supply volume and internal and external differential pressure of 4 types of PPBH(denoted as A,B,C and D)were tested in micro-circumstance airtight cabin,and the inward leakage(IL)at different concentrations of bioaerosol and physical aerosol was also tested.RESULTS Both the internal and external differential pressure and the air supply volume of the 4 types of PPBH met the standards.The PPBH sample A,B and C showed good protective performance for the bioaerosol,while the PPBH sample D showed poor protective performance for the bioaerosol.The IL of the PPBH sample B was less than 0.01％against different concentrations of aerosols,the IL of the PPBH sample D was more than 0.01％against different concentration of aerosols,and the IL of both PPBH sample A and C was less than 0.01％against different concentrations of bioaerosols.However,the IL was more than 0.01％against some of the physical aero-sols with the particle diameter of 0.3 μm and 0.5 μm;with the increase of concentrations of the physical aerosols,the IL of the PPBH sample B,C and D was increased.The IL of the PPBH was greater to the 0.3 μm than to the 0.5 µm in the environment of different concentrations of physical aerosols.The IL of the PPBH samples A,B and C was 0％against the bioaerosols in the environment of different concentrations of bioaerosols,while the IL was more than 0％against the physical aerosols.CONCLUSION The protective performance of the PPBH is affected by the concentration and particle diameter of the tested aerosols.The higher the concentration and the smaller the particle diameters,the greater the corresponding IL,indicating that the PPBH is at high risk of leakage when the concentration is high and the particle diameter is small.The IL of the same PPBH is lower to the bioaerosols than to the physical aerosols.The test result for the protective performance of PPBH against the physical aerosols can represent the level of protection against the harmful biologicalsubstances.
Positive pressure bio-protective hoodProtective performanceConcentration of aerosolSize of aero-solAerosol samplingInward leakageExperimental research
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