AS NZS 16900.14:2021 pdf free download – Respiratory protective devices – Methods of test and test equipment
5  General test requirements
Unless otherwise specified, the values stated in this document are expressed as nominal values. Except for temperature limits, values which are not stated as maxima or minima shall be subject to a tolerance of ±5 %. Unless otherwise specified, the ambient conditions for testing shall be between 16 °C and 32 °C and (50 ± 30) % RH. Any temperature limits specified shall be subject to an accuracy of ±1 °C. For each of the required measurements performed in accordance with this document, a corresponding estimate of the uncertainty of measurement shall be evaluated. This estimate of uncertainty shall be stated when reporting test results, in order to enable the user of the test report to assess the reliability of the result in accordance with Annex A. NOTE  Uncertainty of measurement can be calculated in accordance with JCGM 100 [3] .
6.1  Principle
The RPD is operated on the RPD headform 3 1) (medium size) as specified in ISO 16900-5, equipped with the special ear inserts shown in Figure 1. The RPD headform is attached to the RPD torso as specified in ISO 16900-5 and connected to a breathing machine or metabolic simulator. Microphones are placed in the special ear inserts, details of which are shown in Figure 2 to 4, to measure the A-weighted continuous equivalent sound pressure level generated by the RPD, exclusive of any warning device, at the right and left ears. Measurements on both ears can be performed either in parallel or sequentially. The RPD headform 3 shall be used regardless of the size of the respiratory interface and shall be attached to the RPD torso to avoid reflected noise.
6.2  Equipment
a) The RPD headform 3 with soft surface finish fixed to the RPD torso shall be used. The torso shall be covered with a cotton T shirt. A pressure microphone, 12 mm in diameter shall be fitted in each special ear insert in the position as shown in Figure 5. The surface of the microphone shall be positioned at the surface of the flat ear ±1 mm.
b) The measurement system shall meet the IEC 61672-1 Class 2 standard for sound level meters and shall be capable of measuring the A-weighted continuous equivalent sound pressure level in decibels.
c) A sound level calibrator meeting IEC 60942 Class 2.
d) A suitable adaptor (see Figure 6) for the microphone system and sound level meter.
e) A breathing machine or metabolic simulator as appropriate.
The test environment, including test enclosure should not include surfaces that can reflect sound from the specimen.
6.3  Procedure
a) The microphone(s) shall be mounted in the RPD headform at the position shown in Figure 5
b) The sound level meter and microphone system shall be calibrated using the specified sound level calibrator [see 6.2 c)]. The sound level calibrator including the adaptor shall be tightly fitted onto the microphone (See Figure 6). The sound level calibrator applies a sinusoidal tone to the microphone which is used by the sound level meter for calibration. The sound level calibrator and adaptor shall
be removed after calibration.
c) The breathing machine or metabolic simulator shall be operated at the appropriate workrate for the class of the RPD.
d) The background noise level in the test room shall be measured, without the RPD fitted to the RPD headform, but with the breathing machine or metabolic simulator operating. The background noise level shall be a maximum of 70 dBA.
e) With the breathing machine or metabolic simulator switched off or disconnected, the RPD shall be fitted on the RPD headform and torso, making all the necessary adjustments to ensure a good fit with reference to the information supplied by the manufacturer.