ISO 16900-1 Respiratory Protective Devices - Test Methods and Test Equipment - Part 1: Determination of Inward Leakage

The standard "ISO 16900-1 Respiratory protective devices - Test methods and test equipment - Part 1: Determination of inward leakage" published by the International Organization for Standardization (ISO) describes test methods to determine the inward leakage of respiratory interfaces and the total inward leakage of complete respiratory protective devices at specified metabolic work rates, using specified test agents and incorporating specified body movements. These tests are performed in laboratories using specified test agents under specified conditions and therefore do not represent the performance of the device in actual use.

For the purposes of this standard, in addition to the terms and definitions given in ISO 16972 Respiratory protective devices - Vocabulary and graphical symbols, the following definitions apply:

• Respiratory protective equipmentRefers to filtration where air is forced through filters by means of a blower in addition to the user's breathing.
• Porous device refers to a respiratory protective device that contains materials, excluding filters, through which gases and vapors can penetrate during the inward leakage test. This leads to increased inward leakage.
• Unassisted filtration refers to filtration in which air is drawn through the filters solely by the user's breathing.

Performance standards should specify test conditions. Prerequisites described in this standard include:

• Minimum number of test samples
• Working conditions of respiratory protective equipment
• Exercise regimen to be used
• Use of crosswinds during specific test exercises, if appropriate
• Any exclusions from the test exercise regimens in Appendix B
• Any preconditioning, preconditioning sequence, or testing required
• Any accessory of the respiratory protective device to be included in the evaluation
• Selection of test panel candidates

Unless otherwise stated, values ​​stated in this standard are expressed as nominal values. Values ​​not stated as maximum or minimum, except for temperature limits, are subject to a tolerance of plus/minus 5 percent. Unless otherwise stated, ambient conditions for testing shall be between 16 degrees and 32 degrees and 50 percent plus/minus 30 percent relative humidity. Any temperature limits stated are subject to accuracy of plus/minus 1 degree.

For each of the required measurements performed in accordance with this standard, a corresponding estimate of the measurement uncertainty is evaluated. This uncertainty estimate is stated when reporting test results to enable the user of the test report to assess the reliability of the result in accordance with the annex to this standard (Annex A). The measurement uncertainty is calculated in accordance with Joint Committee on Metrology Guides 100.

In principle, when testing, a subject wearing a respiratory protective device performs a series of exercises while surrounded by an atmosphere containing a known concentration of the test substance. During these exercises, the concentration of the test substance inside and outside the respiratory interface is measured and compared.

Three test substances are specified for test substance selection: a solid aerosol, a liquid aerosol and a gas. The general principle of the test is the same for all substances. The test substances used depend on the type of respiratory protective device being tested (selected according to the figures given in the standard). When sodium chloride is used as the test substance for type T respiratory interfaces (tight fit), Method 2A (impulse sampling) is used. When the choice of gas or aerosol is permitted, aerosol test methods are preferred. Sulfur hexafluoride is a greenhouse gas and is considered undesirable if avoided.

According to this standard, three test items are specified for inward leakage tests:

• Test substance 1 = Sulfur hexafluoride gas
• Test substance 2 = Sodium chloride aerosol
• Test item 3 = Corn oil

All three test materials are equally acceptable for determining inward leakage or total inward leakage, subject to the selection requirements in the standard. If the results from the porosity test of the materials indicate porosity, the respiratory protective device shall be tested using sulphur hexafluoride gas.

Unless otherwise specified in the performance standards, the test panel consists of 15 test subjects selected according to the following criteria:

• Test panel candidates are measured for face length and face width in accordance with Annex C of the ISO/TS 16976-2 standard.
• Candidates' face length and face width measurements are used to assign candidates to cells of the bivariate panel according to the ISO/TS 16976-2 standard.
• Candidates whose bivariate measurements for facial width and length fall outside the panel boundaries will not be used as test subjects.
• When selecting subjects for a test panel, the size of the respiratory interface as defined by the manufacturer is taken into account. In certain cases, neck circumference may need to be taken into account.
• If a respiratory protective device equipped with a tight-fitting respiratory interface (Type T) is being tested, the fit of the respiratory interface should be assessed on each subject in accordance with the method specified in the information provided by the manufacturer of the respiratory protective device. If the respiratory interface does not fit the subject in accordance with the testing required by the manufacturer, that subject is removed from the test panel and replaced with an alternative test subject. The fit assessment described is performed in a separate test prior to the inward leakage assessment.

Our organization has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. Among the numerous test, measurement, analysis and evaluation studies provided for businesses in various sectors, there are also test services in accordance with the standard “ISO 16900-1 Respiratory protective devices - Test methods and test equipment - Part 1: Determination of inward leakage”.