AEROSOL PENETRATION BEHAVIOR OF RESPIRATOR VALVES

负压空气提供的有害气溶胶防护 净化呼吸器取决于过滤器和阀门的性能 和面罩贴合。 据推测，后者是最 呼吸器防护的重要因素。 然而，呼吸阀 故障可能会显着增加呼吸器防护能力的降低。 没有工作 已经完成，以证明阀门在循环流压力下的行为 随着时间的推移。 这项研究将检查气溶胶渗透和泄漏流 负压空气净化呼气阀和吸气阀 呼吸器。 来自多家制造商的新阀门将受到压力 两种工作速率下的八小时循环流。 五粒子穿透 直径在 0.1 到 1 μm 之间的尺寸将在期间定期测量 每次测试。 同时，静压下阀门的泄漏流量将 的确定方式类似于目前国家所使用的方式 职业安全与健康研究所测试呼吸器 呼气阀。 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 将进行测量。 工作率和使用时间将通过以下方式估算 观察和采访呼吸器佩戴者，以及使用和使用历史 维护费用将从雇主的记录中获得。 描述给定颗粒尺寸相关渗透的模型 工作率和泄漏流量将通过泄漏面积的测量来确定 和阀门尺寸。 使用该模型的预测将与 在不同的工作速率下获得的结果。 阀门是呼吸器的重要元件，其部分部件 失败可能会严重损害所提供的保护。 这些 实验将确定初始气溶胶渗透特性 呼吸器阀门，以及由于压力而可能发生的变化 时间。 阀门型号（制造商）、工作率和维护的影响 将探索该计划，以了解可能的范围 阀门功效。 这些实验的结果将有助于开发 更好的阀门测试方法、更好的阀门设计以及 确定适当的阀门使用时间和维护。 在 此外，这些结果将有助于确定阀门的影响 随着时间的推移和使用情况，呼吸器提供的保护效果。

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.