A defect in the isolation equipment for COVID-19 suspects
We have studied the technical requirements of negative pressure isolation equipment for epidemic prevention in COVID-19 issued by various customs and airports. And after consulting the technical specifications of the relevant suppliers, an extremely unsafe technical issue was discovered.
In the technical requirements of negative pressure isolation equipment for epidemic prevention of COVID-19 and the technical specifications of relevant suppliers. The negative pressure isolation room requires an indoor air circulation system with fresh air. To maintain negative pressure inside the isolation room, it is necessary to exhaust air to the outside at all times. If there is a suspected person infected with COVID-19 in the isolation warehouse. The above-mentioned exhaust system poses serious potential hazards."The device of the exhaust system to prevent COVID-19 from leaking out only requires the use of high-efficiency filters."
Efficiency level of high-efficiency filter：H10、H11、H12、H13、H14。
H10(EN18822)：≥85%@MPPS(≥90%@0.3UM)；
H11(EN18822)：≥95%@MPPS(≥99%@0.3UM)；
H12(EN18822)：≥99.5%@MPPS(≥99.9%@0.3UM)；
H13(EN18822)：≥99.99%@MPPS(≥99.99%@0.3UM)；
H14(EN18822)：≥99.995%@MPPS(≥99.999%@0.3UM)
Efficient filters can block particles with a diameter of 0.3 μ m or more. Even the H14 ultra efficient filter can only block particles with a diameter of ≥ 0.3 μ m. However, the diameter of novel coronavirus is 0.06 to 0.14 μ m, which can not be stopped by high efficiency filter. If customs and airports only use high-efficiency filters to handle the exhaust of polluted air from negative pressure isolation rooms. Only the aerogel containing COVID-19 can be blocked. COVID-19 can pass through the high efficiency filter. After passing through the filter, if the climate conditions are suitable, COVID-19 can be transmitted by other media such as external aerogels. Or gather on high-efficiency filters. The cold weather in winter will also extend the active time of COVID-19 to several days. There is a possibility of serious pollution in the surrounding environment of the high-efficiency exhaust filter!
Our EST company's main design is to install two-stage UV disinfection and sterilization devices before and after the high efficiency filter for air exhaust. That is, in the exhaust duct, the exhaust air passes through the high efficiency filter after the first UV disinfection and sterilization, and then the second UV disinfection and sterilization. Only in this way can we ensure that the air discharged from the negative pressure isolation room to the environment is absolutely safe. As shown in the figure:
We have reviewed relevant regulations and provisions:
In the national technical standard GB/T35428-2017, Article 4.3.4 states: "The exhaust from polluted areas should be filtered by high-efficiency filters before being discharged. The high-efficiency filters for exhaust should be able to be collected, disinfected, and sterilized in situ to ensure that the filters are installed without leaks. When replacing the filters, they should be disinfected first, operated by professional personnel, and appropriate protective measures should be taken."
In the local standard DB11/XXX -2008 of Beijing, Article 7.6 states: "Negative pressure isolation wards and their bathrooms should use leak free, disposable, and safely detachable devices for ventilation; high-efficiency filters must be scanned and leak checked on site before installation of leak free devices; filter replacement should be carried out by professionals and protective measures should be taken."
In the standard of emergency medical facilities for novel coronavirus infectious diseases in the construction industry "T/CECS 661-2020", 7.0.10.2: "The exhaust air shall be filtered by high-efficiency filter before discharge."
In view of the spread of new variant COVID-19, there is a trend of expansion in China at present. If more thorough and strict measures are not taken to constrain movable negative pressure isolation equipment. The exhaust air is only used with a primary high-efficiency filter to block COVID-19. This serious technical flaw will make airport and customs epidemic prevention work more difficult or ineffective.
英特东方模拟测试技术（北京）有限公司
EST Simulation Test Technology (Beijing) Co.Ltd
January 20, 2021