ISO 16900-2 Respiratory Protective Devices - Test Methods and Test Equipment - Part 2: Determination of Respiratory Resistance

The standard “ISO 16900-2 Respiratory protective devices - Test methods and test equipment - Part 2: Determination of respiratory resistance” published by the International Organization for Standardization (ISO) describes respiratory resistance test methods for:

• Respiratory protective devices
• Filters for respiratory protective devices
• Respiratory interfaces

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:

• Static breathing resistance is the resistance of a breathing gas when it is passed through the device at a constant flow. respiratory protective device refers to the differential pressure caused by.
• Dynamic respiratory resistance refers to the differential pressure caused by a respiratory protective device when the respiratory gas is moved by a respirator, adjusted for a specific minute ventilation, including respiratory frequency, waveform, and tidal volume.

To apply this standard, at least the following parameters must be specified in the performance standard:

• Number of samples
• Support selection and types such as respiratory protective device head form and body
• Situation in which respiratory interfaces or respiratory protective devices will be tested
• Any prior conditioning or testing
• Flow rate (static test method)
• Flow rate (minute ventilation) including respiratory frequency, tidal volume and waveform (dynamic) testing method
• Any deviation from the methods

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 a relative humidity of 50 percent plus/minus 30 percent. 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 evaluate the reliability of the result in accordance with the annex to this standard (Annex A).

All flow velocity values ​​shall be corrected to 1 013 hPa and 20 degrees. Measurement uncertainty is calculated in accordance with Joint Committee on Metrology Guidelines 100.

When performing “Method 1: Static inhalation resistance for filters and respiratory interfaces,” the filter or respiratory interface is mounted on a support and air is drawn through the device at a constant flow rate. The convention for reporting inhalation resistance is that if the pressure relative to the atmosphere within a respiratory interface or downstream of a filter is negative during the inhalation resistance test, the result is prefixed with a “-”. If the relative pressure within a respiratory interface is positive, the result is prefixed with a “+”. The pressure drop across a filter is reported without any prefix.

The main equipment used in this method includes:

• Pressure gauge calibrated within range to performance standard.
• Flow meters calibrated over the appropriate volumetric flow rate range and corrected for ambient temperature and ambient atmospheric pressure during use.
• Ambient temperature and ambient atmospheric pressure measuring equipment.
• Regulated blower/compressed air source or variable suction device.
• Device support (e.g. filter holder or associated respiratory protective device headform).

The filter holder can be provided by the manufacturer of the respiratory protective device. It is important that the device support does not reduce the effective working area of ​​the filter or respiratory protective device.

The procedure for respiratory protection device filters is as follows:

• Air is drawn through the filter and filter holder system. The pressure drop between the medium and the filter holder is measured through a pressure port fitted at a suitable point between the connection to the suction device.
• It is necessary to ensure that the filter is in the condition specified in the performance standard.
• The filter is fitted in a leak-tight manner as shown in the figure given in the standard. Appropriate airflow is drawn through the filter holder system as specified in the performance standard. The pressure drop is measured and recorded.
• The filter is removed, the same airflow is drawn through the filter holder system and the pressure drop is measured and recorded.
• The breathing resistance of the filter is calculated and reported according to the formula given at the specified flow rate.

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 16900-2 Respiratory protective devices - Test methods and test equipment - Part 2: Determination of respiratory resistance”.