GB/T 38723-2020 English PDF (GBT38723-2020)

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GB/T 38723-2020: Determination of emission rate of volatile organic compounds from wooden furniture -- Concentration history method
GB/T 38723-2020
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 97.140
Y 80
Determination of emission rate of volatile organic
compounds from wooden furniture - Concentration
history method
ISSUED ON: APRIL 28, 2020
IMPLEMENTED ON: NOVEMBER 01, 2020
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 ... 4 
4 Principle ... 5 
5 Test methods ... 5 
6 Result representation ... 8 
Annex A (informative) Fitting methods and examples ... 10 
Determination of emission rate of volatile organic
compounds from wooden furniture - Concentration
history method
1 Scope
This Standard specifies the principle, terms and definitions, test methods and
result calculation for concentration history testing method of emission rate of
formaldehyde, benzene, toluene, xylene, total volatile organic compounds
(TVOC) in wooden furniture.
This Standard is applicable to testing of emission rate of formaldehyde,
benzene, toluene, xylene, total volatile organic compounds (TVOC) in wooden
furniture. The testing of emission rate of other volatile organic compounds may
refer to this Standard.
2 Normative references
The following referenced documents are indispensable for the application of
this document. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any
amendments) applies.
GB 18584, Indoor decorating and refurbishing materials - Limit of harmful
substances of wood based furniture
GB/T 18801-2015, Air Cleaner
GB/T 31106-2014, Determination of volatile organic compounds in furniture
GB/T 31107, Environmental chamber for the determination of volatile organic
compounds of furniture - General technical requirements
GB/T 35607, Green product assessment - Furniture
3 Terms and definitions
For the purposes of this document, the terms and definitions defined in
GB18584, GB/T 31106-2014, GB/T 31107, GB/T35607 as well as the followings
5.1.1 Climate chamber
It shall meet the requirements of GB/T 31107. The number of air changes when
the climate chamber is closed shall be less than 0.03h-1. See A.2 of GB/T
18801-2015 for the test method.
5.1.2 Sampling instruments and equipment
It shall meet the requirements of Clause 4 and Clause 5 in GB/T 31106-2014.
5.2 Test conditions
During the test, the test conditions in the climate chamber shall meet:
- Temperature of (23±2)°C;
- Relative humidity of (45±5)%;
- Air velocity of 0.1m/s~0.3m/s.
5.3 Sample
5.3.1 Measurement and calculation of emittable area
Use measuring equipment to measure the size of each wooden part of the
wooden furniture sample. Calculate the emittable area of the sample. Those
with carved patterns on the surface are treated with planes. If a steel ruler or
tape measure is used, the accuracy is not less than 1mm. If an area tester is
used, the accuracy shall not be less than 1mm2.
5.3.2 Pretreatment
Assembled products, folding products, and adjustable products shall be
assembled, opened, and adjusted according to the style that is most conducive
to emit harmful substances. Generally, conduct pretreatment according to the
whole product. The surface of all parts of the product shall be exposed to the
pretreatment environment.
Pretreatment time is (120±2)h.
The pretreatment environmental conditions are:
- Temperature is (23±2)°C;
- Relative humidity is (45±10)%;
- The distance between samples is not less than 300mm; the placement and
direction shall try to avoid mutual interference between samples due to
airflow;
formaldehyde sampling flow rate shall be 0.5L/min~1.0L/min. The sampling flow
of benzene series and TVOC shall be 200mL/min. During the test, the total
sample volume shall not exceed 10% of the volume of climate chamber.
5.4.4 Determination and analysis of volatile organic compound samples
According to the provisions of Clause 4 and Clause 5 in GB/T 31106-2014,
analyze the collected samples of volatile organic compounds.
6 Result representation
According to the results of the concentration of volatile organic compounds
obtained by determination and analysis, according to formula (1), the
concentration and time of each target volatile organic compound in the chamber
are respectively linearly fitted. The slope is a0 (R2≥0.90). If R2 is less than 0.90,
and the concentration at the initial moment of the closed phase is lower than
the 0.5th hour concentration result, sequentially obtain the slope between the
target volatile organic compound concentration at each time and the
concentration at the initial time of the closed phase. Take the maximum value
as a1. If R2 is less than 0.90, and the initial concentration of the closed phase is
higher than the 0.5th hour concentration result, then sequentially obtain the
slope between the concentration at each time after the 0.5th hour and the
concentration at the 0.5th hour. Take the maximum value as a2. See Annex A
for R2 calculation method and fitting example. The calculation result keeps three
decimal places.
Where,
a0 - Linear fit slope, in milligrams per cubic meter hour [mg/(m3·h)];
ρt - Target volatile organic compound concentration in the climate chamber, in
milligrams per cubic meter (mg/m3);
t - Time the sample is placed in the climate chamber, in hours (h);
b - Linear fit intercept, in milligrams per cubic meter (mg/m3).
The emission rate per area of target volatile organic compound of wood
furniture samples is calculated according to formula (2):