GB/T 38979-2020Sanitary wares—Test method for flushing noise of toilet (English PDF)

3.1 Measurement time interval

It is used to determine the time of integration of the sound level meter for the A- weighted cumulative percentage sound pressure level of the flushing noise of the to-be-tested toilet sample.

3.2 Standard test operator

The personnel who are required to operate the to-be-tested toilet sample to complete the flushing process.

4.1 Test room

The test room should be a semi-anechoic room or a rigid-wall room; the background noise on the hemispherical measurement surface shall be more than 3 dB(A) lower than the average value of the A-weighted equivalent sound level LAeq of the flushing noise of the to-be-tested toilet sample.

4.2 Measuring instruments

The sound level meter for measurement shall meet the requirements for Grade- 2 instrument in GB/T 3785.1; it is recommended to use a Grade-1 instrument.

The sound calibrator shall meet the Grade-1 accuracy requirements in GB/T 15173.

5.1 Sample quantity and specifications

Take a toilet sample.

5.2 Toilet matching requirements

5.2.1 For matching products, install the to-be-tested toilet sample in accordance with the manufacturer's instructions; conduct a connection tightness test under the test static pressure of 0.14 MPa ± 0.01 MPa, to ensure that the toilet and its flushing devices have the overall tightness in good condition.

5.2.2 For non-matching products, the to-be-tested toilet sample can be equipped with a gravity flushing device that meets the requirements of rated water consumption, has an anti-siphon function and meets the requirements of GB/T 26730; the working water level of the flushing tank shall meet the needs of the normal flushing process.

5.3 Installation and orientation of the toilet sample

Place the to-be-tested floor-type toilet sample or the sanitary ware support that contains the wall-mounted toilet sample on the floor of the semi-anechoic room or rigid-wall room; make the distance between the center and any wall not less than 1.5 m.

6.1 Determination of size of the sound source reference body

Use the to-be-tested toilet sample as the sound source reference body; put down the toilet seat; lift the cover.

6.4 Sound pressure level measurement procedures

6.4.1 In a semi-anechoic room or a rigid-wall room that meets the requirements, locate each measurement point according to the microphone position coordinates on the hemispherical measurement surface. Then, move the sound level meter to the position of each measurement point in turn; ensure that the orientation of the microphone is the same as the incident angle of the sound wave when it is calibrated and it perpendicularly points to the measuring surface. Position number

6.4.4 Before testing the flushing noise of the toilet sample, it shall meet the requirements for water consumption in GB/T 6952.

6.4.5 Under the specified test static pressure, start the flushing device and time it in the normal way (generally no more than 1 s); use the A-weighted fast-time weighting characteristic "F" of the sound level meter to respectively measure the A-weighted cumulative percentage sound pressure levels LpAi(50) and LpAi(10) of the toilet flushing noise on the hemispheric measurement surface and record them.

7.1 Calculation of the average value of A-weighted cumulative percentage

sound pressure level

7.2 Background noise correction

The background noise correction values K1A(50) and K1A(10) of the A-weighted cumulative percentage sound pressure level are calculated according to Formula (5) and Formula (6) respectively.

7.3 Test environment correction

Calculate the environment correction value K2A according to Formula (7).

7.5 Calculation of the sound power level

During the normal flushing cycle, the sound power levels LWA (50) and LWA (10) under the meteorological conditions of the test site are calculated according to Formula (10) and Formula (11) respectively.

8.1 Combined standard uncertainty uLWA of the A-weighted sound power

level measurement The uncertainty uLWA of the toilet flushing noise sound power level that is measured according to this Standard is characterized by its total standard deviation sigma tot; it's calculated according to Formula (12).

8.2 Determination of sigma omc

Under the test static pressure of 0.14 MPa ± 0.01 MPa, the same standard test operator uses the same sound level meter, and, according to the test procedures that are specified in Chapter 6, uses the point that is numbered 10 on the hemispheric measurement surface as the microphone position coordinate,

8.3 Determination of sigma R0

8.3.1 Reproducibility standard deviation sigma R0

Reproducibility standard deviation sigma R0 includes measurement method, repeatability of sound pressure level measurement, measurement surface area, background noise correction, test environment correction, meteorological condition correction, sound level meter performance, number of measurement points, angle difference between the noise source acoustic emission direction and the measurement surface normal, frequency spectrum shape and tuned sound and other uncertainty components; it's calculated according to Formula (15).

8.3.7 Uncertainty caused by the meteorological condition correction

The uncertainty, which is caused by the reference quantity difference that is used for sound pressure level and sound power level, and the change of sound power level with temperature and pressure, is umet = 0.3 dB; the sensitivity coefficient is cmet = 1.When the altitude of the test site is less than 1 500 m, no meteorological condition correction is required; when the altitude is greater than 1 500 m, perform the meteorological condition correction in accordance with ISO 3744.

8.3.10 Uncertainty caused by the angle difference between the sound

source acoustic emission direction and the measurement surface normal In a semi-anechoic room, the uncertainty which is caused by the angle difference between the acoustic emission direction of the toilet flushing noise and the hemispherical measurement surface normal is uangle = 0.25 dB; the sensitivity coefficient is cangle = 10-0.1K2A. For a rigid-walled room, it is recommended to analyze the influence of the sound source and its directivity, measurement distance and other factors to determine the standard uncertainty reasonably.