Plebani Carmela, Listrani S, Di Luigi M
ISPESL--Dipartimento Igiene del Lavoro, Laboratorio Dispositivi di Protezione--Monte Porzio Catone (RM).
Med Lav. 2010 Jul-Aug;101(4):293-302.
Electrostatic filters are widely used in applications requiring high filtration efficiency and low pressure drop. However various studies showed that the penetration through electrostatic filters increases during exposure to an aerosol flow.
This study investigates the effects of prolonged exposure to an oily aerosol on the penetration through filtering facepieces available on the market.
Some samples of FFP1, FFP2 and FFP3 filtering facepieces were exposed for 8 hours consecutively to a paraffin oil polydisperse aerosol. At the end of the exposure about 830 mg of paraffin oil were deposited in the facepiece.
All the examined facepieces showed penetration values that increased with paraffin oil load while pressure drop values were substantially the same before and after exposure. The measured maximum penetration values did not exceed the maximum penetration values allowed by the European technical standards, except in one case. According to the literature, 830 mg of oil load in a facepiece is not feasible in workplaces over an eight- hour shift. However, the trend of the penetration versus exposure mass suggests that if the load increases, the penetration may exceed the maximum allowed values. For comparison a mechanical filter was also studied. This showed an initial pressure drop higher than FFP2 filtering facepieces characterized by comparable penetration values. During exposure the pressure drop virtually doubled while penetration did not change.
The increase in penetration with no increase in pressure drop in the analyzed facepieces indicates that it is necessary to comply with the information supplied by the manufacturer that restricts their use to a single shift.
静电过滤器广泛应用于需要高过滤效率和低压力降的场合。然而，多项研究表明，在暴露于气溶胶流期间，通过静电过滤器的穿透率会增加。
本研究调查长时间暴露于油性气溶胶对市售过滤面罩穿透率的影响。
将一些FFP1、FFP2和FFP3过滤面罩样品连续暴露于石蜡油多分散气溶胶中8小时。暴露结束时，约830毫克石蜡油沉积在面罩中。
所有检测的面罩显示，穿透率值随石蜡油负载量增加而增加，而暴露前后的压力降值基本相同。除一个案例外，测得的最大穿透率值未超过欧洲技术标准允许的最大穿透率值。根据文献，在一个八小时轮班期间，面罩中830毫克的油负载量在工作场所是不可行的。然而，穿透率与暴露质量的趋势表明，如果负载量增加，穿透率可能超过允许的最大值。为作比较，还研究了一个机械过滤器。结果显示，其初始压力降高于具有可比穿透率值的FFP2过滤面罩。在暴露期间，压力降几乎翻倍，而穿透率没有变化。
所分析面罩中穿透率增加而压力降未增加，这表明有必要遵守制造商提供的信息，即限制其使用为单班制。
