GB/T 39764-2021Volatile organic compounds from upholstered furniture—On-site and rapid detection method (English PDF)

3.1 Volatile organic compounds from upholstered furniture

Volatile organic compounds released from the tested surface of upholstered furniture and tested by on-site and rapid detection method.

3.2 Background clean

The background clean can be performed by either internal circulation (7.3.2) or nitrogen purging mode (7.3.3).

7.3.2 Internal circulation

7.3.2.1 Adjust the three-way valve (position 6 in Figure 1) to the upper passage position.

7.3.2.2 Set the flow rate of the gas pump (position 3 in Figure 1) to 600 mL/min. Set the running time to 30 min.

7.3.2.3 Start the gas pump (position 3 in Figure 1). The air in the entire device generates circulating power; so that the air in the collector, at a flow rate of 600 mL/min, passes through the mixing filter pipe (position 7 in Figure 1) and then returns to the collector. The volatile organic compounds in the ambient background air are absorbed by the mixing filter pipe (position 7 in Figure 1), to form clean air circulation to replace the air in the collector.

7.3.3 Nitrogen purging

Connect the nitrogen source (position 13 in Figure 1) to the intake port (position 1 in Figure 1) on the left side of the mask body. Open the top exhaust port (position 2 in Figure 1) to exhaust nitrogen. Turn on the nitrogen source, to purge the air in the mark body at a flow rate of 1 L/min, for no less than 18 min; replace the air in the mask body with nitrogen. After purging, immediately turn off the nitrogen source and the top exhaust port.

7.4 Cyclic enrichment

7.4.1 After the background clean, adjust the three-way valve (position 6 in

Figure 1) to the lower passage position.

7.4.2 Start the thermostat (position 9 in Figure 1) to control the heating temperature to (40±2)°C. Start the gas pump (position 3 in Figure 1). The temperature of the air entering at the entrance (position 10 in Figure 1) of the test mask body shall be (36±2)°C. When the air temperature at the entrance does not meet the requirement of (36±2)°C, the thermostat (position 9 in Figure

1) shall be adjusted. The VOCs released by the sample are enriched in the collector. The circulating gas flow is 600 mL/min. The enrichment time is 30 min.

7.5 Sampling and rapid VOCs analysis

7.5.1 General

The total amount of gas analyzed in each sampling shall not be greater than 80% of the volume of the mask body.

If the amount of gas collected for sampling analysis is greater than 10% of the volume of the mask body, when the test is continued, 7.4.2 cyclic enrichment shall be repeated before sampling.

Under the condition of meeting the detection requirements, the collection parameters can be set according to the instructions for use of the instrument.

7.5.2 Rapid formaldehyde analysis

After the end of the cyclic enrichment, within 30 s, turn on the gas circuit switch (position 5 in Figure 1); connect the rapid VOCs analyzer (position 15 in Figure

1) with the on-site and rapid collection equipment. Collect the gas in the mask body for analysis. The reading displayed on the rapid formaldehyde analyzer is the formaldehyde concentration value. The measured value of volume fraction shall, according to formula (15) in 7.4.4.1 of GB/T 18204.2-2014, be converted into mass concentration.

7.5.3 Rapid analysis for other aldoketone VOCs

After the end of the cyclic enrichment, within 30 s, turn on the gas circuit switch (position 5 in Figure 1); connect the rapid VOCs analyzer (position 15 in Figure

1) with the on-site and rapid collection equipment. At a rate of 100 mL/min, collect the gas in the mask body into the rapid analyzer for other aldoketone VOCs. At the same time of collecting, at the left supply port (position 1 in Figure

1), at the same flow rate, replenish nitrogen (6.2) to the mask body, to maintain the pressure balance in the system. When the sampling is completed, stop replenishing gas. When replenishing gas, at the left supply port (position 1 in

Figure 1), it is possible to connect a supplementary gas bag (6.4) filled with nitrogen. After sampling, the connection shall be disconnected immediately.

The sampling time and gas replenishing time are both 10 min.

After the analysis is completed, the reading displayed on the rapid VOCs analyzer is the concentration value of other aldoketone VOCs.

7.5.4 Rapid analysis for non-aldoketone VOCs

After the end of the cyclic enrichment, within 30 s, turn on the gas circuit switch (position 5 in Figure 1); connect the rapid VOCs analyzer (position 15 in Figure

1) with the on-site and rapid collection equipment. At a rate of 100 mL/min, collect the gas in the mask body into the rapid analyzer for non-aldoketone VOCs. At the same time of collecting, at the left supply port (position 1 in Figure

1), at the same flow rate, replenish nitrogen (6.2) to the mask body, to maintain the pressure balance in the system. When the sampling is completed, stop replenishing gas. When replenishing gas, at the left supply port (position 1 in

Figure 1), it is possible to connect a gas bag (6.4) filled with nitrogen. After sampling, the connection shall be disconnected immediately. The sampling time