Horizontal and vertical combustion tester is used to simulate the material UL94 combustion test device, combustion performance refers to some physical and chemical changes that occur when the material burns or encounters fire, this performance is measured by the characteristics of the material surface ignition and flame propagation, heat, smoke, charring, weight loss and the generation of toxic products.
(1) With the rapid development of the plastics industry, the variety of plastic products, involving a wide range of fields, plastic products have become a necessity of our daily life, and therefore to ensure safety and more favorable to promote the production and use of plastic products, combustion performance testing is a necessary task.
(2) Plastic materials are flammable and produce smoke and gas soot harmful to human body in the process of combustion, which is very dangerous and a threat to human life and property safety.
(3) The burning performance test of plastic materials can help and guide us to conduct flame retardant research on materials and regulate the manufacture of plastic products.
There are three main standards for flame retardant test grades for plastics.
(1) GB/T2408-2008 "Determination of burning properties of plastics Horizontal and vertical method
(2) GB/T2406.2-2009 "Plastics Determination of combustion behavior by oxygen index method".
(3) American Standard UL94 flame retardant grade (UL94 flame retardant grade is a very important standard, has been widely adopted.)
There are other standards such as GB/T8924-2005 "Test Method for Combustion Properties of Fiber Reinforced Plastics Oxygen Index Method", ASTM D2863, GB/T 5169.16, GB/T 5169.17, GB 4943.1 and so on. Among them, UL94 is a common flame retardant test standard in the plastic industry, with 12 grades: HB, V-0, V-1, V-2, 5VA, 5VB, VTM-0, VTM-1, VTM-2, HBF, HF-1, HF-2.
UL94 is used to evaluate the ability of a material to extinguish a flame after being ignited. There are various methods of evaluation based on burning speed, burning time, drip resistance and whether the dripping material burns or not. Many values can be obtained for each material tested, depending on color or thickness. The UL rating must be reported together with the thickness value when the material of a product is selected to meet the thickness requirements of the wall part of the plastic part.
I. UL94 common test methods
1、Vertical burning test
Bunsen burned for 10±0.5 seconds after contacting the center of the sample below the Bunsen burner, remove the Bunsen burner at a speed of 300mm/s, at least 150mm from the test piece, and record the first spontaneous combustion time. Immediately after the spontaneous combustion stops, the second burning, burning 10±0.5 seconds, remove the Bunsen burner, and record the second spontaneous combustion time and the incandescent time after the flame is extinguished.
2、Horizontal combustion test
Clamp one end of the test piece horizontally with the level of 45 ± 2 degrees, take a wire mesh, fixed horizontally below the test piece 10 ± 1mm, the Bunsen burner into 45 degrees, move to the other end of the test piece to contact the sample 6mm, and time 30 ± 1 seconds after moving away, to be burned to 25mm mark, start another timer. If the sample is burned to the 25 mm mark within 30±1 seconds, start another timer and move the Bunsen burner away.
3. 5VA Test
Move the Bunsen burner to the test piece at 20±5 degrees from the horizontal, make the tip of the inner flame touch the bottom side of the sample, burn for 5±0.5 seconds, then remove the Bunsen burner for 5±0.5 seconds, repeat this action five times, remove it after the fifth burn and record the self-ignition time and the incandescent time after the flame is extinguished.
Hold the test piece horizontally with jig or fixture, move the Bunsen burner to the bottom of the test piece at 20±5 degrees from the horizontal, the tip of the inner flame touches the bottom center of the sample and burns for 5±0.5 seconds, then move away from the Bunsen burner for 5±0.5 seconds, repeat this action five times, move away after the fifth burn and observe and record whether the test piece is damaged by holes.
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