Standards related to:

GB/T 38979-2020**GB/T 38979-2020: PDF in English (GBT 38979-2020) **

GB/T 38979-2020

GB

NATIONAL STANDARD OF THE

PEOPLE’S REPUBLIC OF CHINA

ICS 91.140.70

Q 31

Sanitary wares - Test method for flushing noise of

toilet

ISSUED ON: JULY 21, 2020

IMPLEMENTED ON: JUNE 01, 2021

Issued by: State Administration for Market Regulation;

Standardization Administration of the People’s Republic of

China.

Table of Contents

Foreword ... 3

1 Scope ... 4

2 Normative references ... 4

3 Terms and definitions ... 5

4 Facility conditions and measuring instruments ... 5

5 Sample installation and commissioning ... 6

6 Sound pressure level measurement ... 7

7 Result calculation ... 10

8 Uncertainty of measurement ... 14

9 Test report ... 19

Sanitary wares - Test method for flushing noise of

toilet

1 Scope

This Standard specifies the facility conditions and measuring instruments,

sample installation and commissioning, sound pressure level measurement,

result calculation, uncertainty of measurement and test report for flushing noise

detection of toilets (not including toilets and smart toilets that use pressure

flushing devices).

This Standard applies to the flushing noise detection of toilets (not including

toilets and smart toilets that use pressure flushing devices).

2 Normative references

The following documents are indispensable for the application of this document.

For dated references, only the dated version applies to this document. For

undated references, the latest edition (including all amendments) applies to this

document.

GB/T 3768-2017, Acoustics - Determination of sound power levels and

sound energy levels of noise sources using sound pressure - Survey method

using an enveloping measurement surface over a reflecting plane

GB/T 3785.1, Electroacoustics - Sound level meters - Part 1: Specifications

GB/T 6952, Sanitary wares

GB/T 15173, Electroacoustics - Sound calibrators

GB/T 26730, Sanitary ware - Gravity water flushing devices and supports

JC/T 764, WC seats

JC/T 932, Drainage fittings for sanitary wares

ISO 3744, Acoustics - Determination of sound power levels and sound

energy levels of noise sources using sound pressure - Engineering methods

for an essentially free field over a reflecting plane

Note: When it comes to the arbitration of the detection result of flushing noise

of the toilet sample, the detection result of the semi-anechoic room shall

prevail.

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 Sample installation and commissioning

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. The WC seats shall comply with JC/T 764. The

sanitary ware support that is used for the wall-mounted toilet sample shall meet

the requirements of GB/T 26730. Use a flange, of a suitable size, that conforms

to JC/T 932, to adjust the drainage method of the rear-row toilet sample to the

bottom delivery type. Then, perform the connection tightness test under the test

static pressure of 0.14 MPa ± 0.01 MPa, to ensure that the toilet and the flushing

devices have good overall tightness.

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. Adjust the actual water consumption of the sample to be less than

or equal to the nominal water consumption; fill the toilet water seal to the normal

water level. When installing the toilet sample, suitable sound insulation

measures such as rubber pads shall be used to avoid interference noise

between the sample (or sanitary ware support) and the ground during the test.

6.4.2 In the full flushing mode, take a complete normal flushing cycle as the

measurement period of the sound level meter's audio frequency signal

acquisition, from the start of the drain valve button to the close of the inlet valve.

6.4.3 Take the normal flushing cycle of the to-be-tested toilet sample as the

measurement period; use the A-weighted equivalent sound level fast-time

weighting characteristic "F" of the sound level meter to determine the A-

weighted accumulative percentage sound pressure level LpAi(B)(50) and LpAi(B)(10)

of the background noise on the hemispherical measurement surface and record

them.

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.

Note: When a multi-channel acoustic analyzer is used for automatic audio

frequency signal acquisition, the acoustic signal acquisition time of the

instrument can be set to no more than 125 ms.

7 Result calculation

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

sound pressure level

Under normal flushing cycle conditions, the A-weighted cumulative percentage

sound pressure level average value _____ L'pA(50) and _____ L'pA(10) of the flushing noise of the

to-be-tested toilet sample are respectively calculated in accordance with

Formula (1) and Formula (2):

Where:

_____

L'pA(50) -- During the normal flushing cycle, the A-weighted cumulative 50% sound

pressure level average value of the toilet flushing noise that is measured

on the hemispherical measurement surface, in decibels (dB);

Keep one significant digit after the decimal point for the measurement results

of the A-weighted cumulative percentage sound pressure level of toilet flushing

noise and background noise LpAi(50), LpAi(10) and LpAi(B)(50), LpAi(B)(10); round the

calculation results of the average values _____ L'pA(50) , _____ L'pA(10) and ______ LpA(B)(50) , ______ LpA(B)(10) to the

nearest integer. Keep one significant digit after the decimal point for the

calculation results of the background noise correction value K1A(50), K1A(10) and

the environmental correction value K2A of the A-weighted cumulative

percentage sound pressure level; round the calculation results of the A-

weighted sound power level LWA(50) and LWA(10) to the nearest integer.

8 Uncertainty of measurement

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 σtot; it’s calculated according to Formula (12):

Where:

uLWA -- uncertainty of sound power level, in decibels (dB);

σtot -- total standard deviation, in decibels (dB);

σR0 -- reproducibility standard deviation of the measurement method, in

decibels (dB);

σomc -- standard deviation of the uncertainty that is caused by the installation

and test conditions of the to-be-tested toilet sample, in decibels (dB).

8.2 Determination of σomc

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, to perform at least 6 repeated measurements of the A-weighted

cumulative percentage sound pressure level average values _____ L'pA(50) and _____ L'pA(10) of

the flushing noise of the same toilet sample that is installed at the same position

in the test room (The toilet needs to be re-installed before each measurement),

and corrects the background noise for the measurement results.

8.3.2 Uncertainty caused by the measurement method

Assume that the uncertainty components in this Standard are not related to

each other, and the modeling method is complete and correct, then, the method

uncertainty that is caused by the residual uncertainty is umethod = 0.6 dB, and

the sensitivity coefficient is cmethod = 1.

8.3.3 Repeatability standard deviation of sound pressure level

measurement

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 of this Standard, uses the point that

is numbered 10 on the hemispheric measurement surface as the microphone

position coordinate, to perform multiple times (at least 6 times) of repeated

measurements of the A-weighted cumulative percentage sound pressure level

average values _____ L'pA(50) and _____ L'pA(10) of the flushing noise of the same toilet sample

that is installed at the same position in the test room (The sound level meter

needs to be repositioned before each measurement).

The uncertainty of the measured value uL'pA(50) and uL'pA(10), namely their

standard deviations sL'pA(50) and sL'pA(10), are calculated according to Formula

(16) and Formula (17) respectively; the upper limit is not more than 1.5 dB.

Where:

L'pA(50),j -- toilet flushing noise A-weighted cumulative 50% sound pressure level

of the jth repeated measurement, in decibels (dB);

L'pA(50)av -- arithmetic average of all repeated measurement results of L'pA(50),j, in

decibels (dB);

L'pA(10),j -- toilet flushing noise A-weighted cumulative 10% sound pressure level

of the jth repeated measurement, in decibels (dB);

L'pA(10)av -- arithmetic average of all repeated measurement results of L'pA(10),j, in

decibels (dB).

The sensitivity coefficients cL'pA(50) and cL'pA(10) of the measured value are

calculated according to Formula (18) and Formula (19) respectively:

issued by its calibration certificate; the corresponding sensitivity coefficient is

cslm = 1.

8.3.9 Uncertainty caused by the number of limited measurement points

The uncertainty which is introduced by the number of limited measurement

points umic is calculated according to Formula (22) and Formula (23); the

corresponding sensitivity coefficient is cmic = 1.

Where:

NM -- number of microphone positions;

L'pA(50)av -- arithmetic average of the measured values of L'pAi(50), in decibels (dB);

L'pA(10)av -- arithmetic average of the measured values of L'pAi(10), in decibels (dB).

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.

8.3.11 Uncertainty caused by the frequency spectrum shape and tuned

sound

Since there is no audible tuned sound in the toilet flushing process, it can be

assumed that the uncertainty which is introduced by the frequency spectrum

shape and tuned sound is utone = 0 dB; the sensitivity coefficient is ctone = 1.

8.4 Extended uncertainty of measurement U

The extended uncertainty of measurement U is calculated according to Formula

(24):

......

Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.