AEROSOL PENETRATION BEHAVIOR OF RESPIRATOR VALVES

负压空气提供的对有害气溶胶的保护- 净化呼吸器取决于过滤器和阀门的性能 而且脸型也很合适。据推测，后者是最重要的 口罩保护中的重要因素。然而，呼吸器阀门 故障可能会大大增加呼吸器的防护能力。没有工作 已经完成，以演示阀门在循环流动时的受力行为 随着时间的推移。 这项研究将检查气溶胶穿透和泄漏流动。 负压空气净化的呼气阀和吸气阀 呼吸器。几家制造商的新阀门将重点放在 在两个工作速率下的八小时循环流量。五个粒子的穿透 直径在0.1至1微米之间的尺寸将在 每一次测试。同时，阀门在静压作用下泄漏流量也会 被确定的方式，类似于国家 用于测试呼吸器的职业安全与健康研究所 呼气阀。 使用过的阀门将从已磨损的呼吸器中获得 工业工作情况和类似的渗透和泄漏流量 将进行测量。工资率和使用时间将通过以下方式估算 观察和访谈佩戴口罩的人，以及使用和使用口罩的历史 维修费将从雇主的记录中获得。 描述与颗粒大小相关的渗透率的模型 将使用泄漏面积的测量来开发工作率和泄漏流量 以及阀门的尺寸。使用此模型的预测将与 在不同的工作速度下获得的结果。 阀门是呼吸器的重要部件，其部分部件 如果失败，可能会严重损害提供的保护。这些 实验将确定初始气溶胶渗透特性 呼吸器阀门，以及由于压力过大而可能发生的变化 时间到了。阀门型号(制造商)、工作速度和维护的影响 将探索计划，以了解可能的范围 瓣膜功效。这些实验的结果将有助于发展 更好的阀门测试方法，更好的阀门的设计，以及 确定合适的阀门使用时间和维护。在……里面 此外，这些结果将有助于确定阀门的影响 关于呼吸器随时间和使用情况提供的保护。

The protection from harmful aerosols afforded by negative pressure air- purifying respirators depends on both the behavior of filters and valves and facepiece fit. It has been hypothesized that the latter is the most significant factor in a respirators protection. However, respirator valve failure may add significantly to a respirators reduced protection. No work has been done to demonstrate valve behavior as stressed with cyclic flow over time. This research will examine aerosol penetration and leak flow through exhalation and inhalation valves from negative pressure air-purifying respirators. New valves from several manufacturers will be stressed with an eight hour cyclic flow at two workrates. Penetration of five particle sizes between 0.1 and 1 mu-m diameter will be measured periodically during each test. At the same time, valve leak flow under static pressure will be determined, in a manner similar to that presently used by the National Institute for Occupational Safety and Health for testing respirator exhalation valves. Used valves will be obtained from respirators which have been worn in industrial work situations and similar penetration and leak flow measurements will be made. Workrate and usage time will be estimated by observing and interviewing the respirator wearers, and history of use and maintenance will be obtained from employer's records. A model to describe particle size-related penetration for a given workrate and leak flow will be developed using measurements of leak area and valve dimensions. Predictions using this model will be compared with results obtained at a different workrate. Valves are important elements of a respirator and their partial failure could severely compromise the protection offered. These experiments will identify initial aerosol penetration characteristics of respirator valves, as well as changes which may occur due to stress over time. Effects of valve model (manufacturer), workrate, and maintenance program will be explored to gain an understanding of the range of possible valve efficacy. Results of these experiments will help in the development of better valve test methods, the design of better valves, and the identification' of appropriate valve usage time and maintenance. In addition, these results will assist in identifying the influence of valves on the protection offered by a respirator over time and usage.