Avaliação da eficiência dos sistemas de ventilação local exaustora em laboratórios de ensino de química: diagnóstico e propostas de melhoria

Abstract

The installation of a Local Exhaust Ventilation System (LEV) is essential in environments where equipment is found that emits contaminants or products that release substances that are harmful to the health of workers who frequent the location. For this reason, chemistry laboratories require exhaust hoods that capture pollutants and eliminate them, through piping and a fan, before they are dispersed throughout the room. Therefore, pointing out this need, the technician of higher education undergraduate laboratories that handle chemical products recommended that the LEV of these locations be analyzed and checked for possible failures. The aim, then, was to increase the safety of researchers, students and professors who work there and reduce environmental impacts. Therefore, two visits were made to the laboratories, with the help of the responsible technician, to collect information and measurements, in addition to studying proposals for relevant solutions that meet a LEV and using equations to calculate the pressure and flow rate required by the system to select the ideal exhaust fan, correctly achieving the objective. Thus, to solve the faults present in the system of these studied locations, two options for dimensioning the three installed hoods were suggested. One of these solutions would be a single pipe connected to the three hoods with diameter reducers in the hoods furthest from the exhaust fan, having to be connected at the same time for any of them to be used. The other solution would be for each hood to have its own pipe and for all three to have the same duct diameter, allowing for less noise, since each one would be connected separately. In addition, to solve other perceived problems, some solutions were proposed: in order to avoid fire and eliminate internal wires in the hoods, on/off buttons were required on the outside of them; for the lack of sealing at the base of the hoods, silicone was required around their entire perimeter; to prevent animals, insects, rain and hail from entering the pipes, Chinese hats and screens were added at the end of each duct; and to the presence of high noise, the exhaust fans were installed outside the laboratories.