42 CFR 84.181 - Non-powered air-purifying particulate filter efficiency level determination.
(a) Twenty filters of each non-powered air-purifying particulate respirator model shall be tested for filter efficiency against:
(1) A solid sodium chloride particulate aerosol as per this section, if N-series certification is requested by the applicant.
(2) A dioctyl phthalate or equivalent liquid particulate aerosol as per this section, if R-series or P-series certification is requested by the applicant.
(b) Filters including holders and gaskets; when separable, shall be tested for filter efficiency level, as mounted on a test fixture in the manner as used on the respirator.
(c) Prior to filter efficiency testing of 20 N-series filters, the 20 to be tested shall be taken out of their packaging and placed in an environment of 85 ±5 percent relative humidity at 38 ±2.5 °C for 25 ±1 hours. Following the pre-conditioning, filters shall be sealed in a gas-tight container and tested within 10 hours.
(d) When the filters do not have separable holders and gaskets, the exhalation valves shall be blocked so as to ensure that leakage, if present, is not included in the filter efficiency level evaluation.
(e) For non-powered air-purifying particulate respirators with a single filter, filters shall be tested at a continuous airflow rate of 85 ±4 liters per minute. Where filters are to be used in pairs, the test-aerosol airflow rate shall be 42.5 ±2 liters per minute through each filter.
(f) Filter efficiency test aerosols.
(1) When testing N-series filters, a sodium chloride or equivalent solid aerosol at 25 ±5 °C and relative humidity of 30 ±10 percent that has been neutralized to the Boltzmann equilibrium state shall be used. Each filter shall be challenged with a concentration not exceeding 200 mg/m 3.
(2) When testing R-series and P-series filters, a neat cold-nebulized dioctyl phthalate (DOP) or equivalent aerosol at 25 ±5 °C that has been neutralized to the Boltzmann equilibrium state shall be used. Each filter shall be challenged with a concentration not exceeding 200 mg/m 3.
(3) The test shall continue until minimum efficiency is achieved or until an aerosol mass of at least 200 ±5 mg has contacted the filter. For P-series filters, if the filter efficiency is decreasing when the 200 ±5 mg challenge point is reached, the test shall be continued until there is no further decrease in efficiency.
(g) The sodium chloride test aerosol shall have a particle size distribution with count median diameter of 0.075 ±0.020 micrometer and a standard geometric deviation not exceeding 1.86 at the specified test conditions as determined with a scanning mobility particle sizer or equivalent. The DOP aerosol shall have a particle size distribution with count median diameter of 0.185 ±0.020 micrometer and a standard geometric deviation not exceeding 1.60 at the specified test conditions as determined with a scanning mobility particle sizer or equivalent.
(h) The efficiency of the filter shall be monitored and recorded throughout the test period by a suitable forward-light-scattering photometer or equivalent instrumentation.
(i) The minimum efficiency for each of the 20 filters shall be determined and recorded and be equal to or greater than the filter efficiency criterion listed for each level as follows: