How to filter dust during the process

LEV works by taking it out of the escape point as soon as it is produced and removing it before it is inhaled or becomes a source of contamination. Its operating costs are generally lower than equivalent dilution ventilation systems.

The system typically includes a partial hood or enclosure, a venting duct system, a filter (typically an automatic purging bag filter), a fan, and a conduit for exhausting the cleaned air out of the system, typically for pharmaceutical use. There is also a restriction filter (typically a HEPA filter) that acts as a final protective filter before the air is vented to the atmosphere. This filter and seal should be inspected periodically for leaks, at least annually, or at intervals specified by local regulations or within the company.

The design of the partial hood is critical to achieving a capture rate that is compatible with the particle size and diffusion pattern of the particles. For example: primary filter G4 filter particle size > 3.0um dust, medium efficiency filter F5-F9 filter particle size > 1.0um dust, high efficiency filter H10-H14 filter particle size > 0.3um dust, ultra-efficient U15-U17 filter The particle size is >0.1um dust, and the design should also ensure reasonable noise level and displacement. Ventilation piping should be designed based on a constant flow rate to ensure that the particles remain in suspension and prevent them from accumulating in the pipeline.

The system can be designed to work continuously to reduce the risk of contamination caused by cross-flow of gas within the facility when the HVAC system is shut down (and thus affects indoor pressure). Air emissions should be considered during the HVAC system balancing process. If the main dust collector is automatically cleaned with counter-current compressed air, the design and commissioning should consider the effect of periodic reduction of flow in the system piping to prevent the risk of contamination caused by instantaneous changes in the indoor pressure difference when the exhaust flow is reduced during the cleaning process.