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Q&A | What is the relationship between GWT, GWFI and GWIT?
Date：2021/10/19 Clicks：995
Glow wire test of finished product (GWT)
Meet the criteria:
1. The test sample does not burn;
2. Although it ignites, it extinguishes within 30s after the glow wire leaves and does not ignite the wrapping paper under the product.
Material Glow Wire Flammability Index (GWFI)
The highest test temperature of a test sample with a specified thickness in three consecutive tests meets the conditions:
1. The test sample does not burn;
2. Although it ignites, it extinguishes within 30s after the glow wire leaves and does not ignite the wrapping paper under the product.
Material glow-wire ignition temperature (GWIT)
1. The highest temperature at the top of the glowing wire that will not cause ignition of the test sample of the specified thickness in three consecutive tests is 25K higher (30K higher between 900°C and 960°C).
Question: Is the literal understanding of GWIT more severe than GWFI?
Answer: This is a misunderstanding, please see the following analysis
Example: When the product does not burn when the material is tested for three consecutive times at the highest temperature of 750℃,
At this time, GWFI: 750°C, and GWIT: 750+25=775°C.
When the material is subjected to three consecutive tests at the highest temperature of 750°C, the sample ignites and extinguishes within 15s when the glow wire is removed. At this time, the GWFI: 750°C; and the GWIT cannot be determined, it needs to be degraded and tested at 700°C. If it does not burn at 700°C ( The burning time is less than 5s), then GWIT: 700+25=725°C at this time.
Conclusion: GWFI and GWIT cannot be compared; generally speaking, the glow wire test GWT performs a series of tests from low temperature to high temperature. The first time a fire occurs is the glow wire ignition temperature GWIT, which is in the qualified and The unqualified threshold "just qualified" is the glow-wire flammability index GWFI.
Question: Under what circumstances do I need to make GWT, GWIT, GWFI for insulating material parts supporting current-carrying connectors?
Answer: Refer to Chapter 30 of the household appliance standard GB 4706.1 (IEC 60335-1) as follows:
Have someone to take care of at work:
For connectors with current carrying over 0.5A, GWT 750℃;
Carrying current does not exceed 0.5A connector, GWT 650℃.
Unattended at work:
For connectors with current carrying over 0.2A, GWFI is 850℃; GWFI is the material pre-selection test. After passing the test, one of the GWIT 775℃ or GWT 750℃ tests can be done; if GWT 750℃ fails, the remedy is Need to conduct further needle flame tests on other surrounding parts.
For connectors with current carrying current not exceeding 0.2A, one of the GWIT 675°C or GWT 650°C tests is sufficient; if GWT 650°C fails, the remedy is to conduct further needle flame tests on other surrounding parts.
As a national CNAS laboratory, Guangzhou Saida Testing Technology Co., Ltd. has carried out testing and certification for home, lighting, IT/AV and other related products in 2006, and professionally provides CCC, CQC, SAA, RCM, CE, TUV, VDE, UL, SABER, COC and other related certifications, all companies are welcome to call or write for consultation!
Guangzhou Saida Testing Technology Co., Ltd.
Room 703, Tianan Energy-saving Technology Park Development Building, 555 Panyu Avenue North, Panyu District, Guangzhou
Contact:
Ms. Jiang Junwen
Mobile phone: 13430319971
Email: sales2@certitek.cn
Mr. Xu Yongde
Mobile: 13148900346
Email: sales2@certitek.cn
Meet the criteria:
1. The test sample does not burn;
2. Although it ignites, it extinguishes within 30s after the glow wire leaves and does not ignite the wrapping paper under the product.
Material Glow Wire Flammability Index (GWFI)
The highest test temperature of a test sample with a specified thickness in three consecutive tests meets the conditions:
1. The test sample does not burn;
2. Although it ignites, it extinguishes within 30s after the glow wire leaves and does not ignite the wrapping paper under the product.
Material glow-wire ignition temperature (GWIT)
1. The highest temperature at the top of the glowing wire that will not cause ignition of the test sample of the specified thickness in three consecutive tests is 25K higher (30K higher between 900°C and 960°C).
2. Light-off: combustion lasting more than 5s
Question: Is the literal understanding of GWIT more severe than GWFI?
Answer: This is a misunderstanding, please see the following analysis
Example: When the product does not burn when the material is tested for three consecutive times at the highest temperature of 750℃,
At this time, GWFI: 750°C, and GWIT: 750+25=775°C.
When the material is subjected to three consecutive tests at the highest temperature of 750°C, the sample ignites and extinguishes within 15s when the glow wire is removed. At this time, the GWFI: 750°C; and the GWIT cannot be determined, it needs to be degraded and tested at 700°C. If it does not burn at 700°C ( The burning time is less than 5s), then GWIT: 700+25=725°C at this time.
Conclusion: GWFI and GWIT cannot be compared; generally speaking, the glow wire test GWT performs a series of tests from low temperature to high temperature. The first time a fire occurs is the glow wire ignition temperature GWIT, which is in the qualified and The unqualified threshold "just qualified" is the glow-wire flammability index GWFI.
Question: Under what circumstances do I need to make GWT, GWIT, GWFI for insulating material parts supporting current-carrying connectors?
Answer: Refer to Chapter 30 of the household appliance standard GB 4706.1 (IEC 60335-1) as follows:
Have someone to take care of at work:
For connectors with current carrying over 0.5A, GWT 750℃;
Carrying current does not exceed 0.5A connector, GWT 650℃.
Unattended at work:
For connectors with current carrying over 0.2A, GWFI is 850℃; GWFI is the material pre-selection test. After passing the test, one of the GWIT 775℃ or GWT 750℃ tests can be done; if GWT 750℃ fails, the remedy is Need to conduct further needle flame tests on other surrounding parts.
For connectors with current carrying current not exceeding 0.2A, one of the GWIT 675°C or GWT 650°C tests is sufficient; if GWT 650°C fails, the remedy is to conduct further needle flame tests on other surrounding parts.
As a national CNAS laboratory, Guangzhou Saida Testing Technology Co., Ltd. has carried out testing and certification for home, lighting, IT/AV and other related products in 2006, and professionally provides CCC, CQC, SAA, RCM, CE, TUV, VDE, UL, SABER, COC and other related certifications, all companies are welcome to call or write for consultation!
Guangzhou Saida Testing Technology Co., Ltd.
Room 703, Tianan Energy-saving Technology Park Development Building, 555 Panyu Avenue North, Panyu District, Guangzhou
Contact:
Ms. Jiang Junwen
Mobile phone: 13430319971
Email: sales2@certitek.cn
Mr. Xu Yongde
Mobile: 13148900346
Email: sales2@certitek.cn
Add.：Room703、705/7F, Development Building, Tian An Hi-Teck Ecological Park, No.555 North Road Panyu Avenue, Panyu District, Guangzhou City, 511400, China
Tel.：020 - 39211670 Fax：020 - 39211640 E-mail:info@certitek.cn