125mm vertical burning test

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125mm vertical burning test for classifying materials 5VA or 5VB

The UL94 125mm vertical burning test evaluates both the burning and afterglow times and any holes that are formed as well as dripping of the burning test specimen.


Specimen:  Four sets of five bar specimens and three plaque specimens. The bar specimens will have nominal dimensions 125mm x 13mm and thickness not to exceed 13mm. The plaque specimen will have nominal dimensions 150mm x 150mm and thickness not more than 13mm.

Specimen conditioning:

Two sets of 5 bar specimens and 3 plaque specimens per sample to be conditioned as follows:

i. First set at 230C and relative humidity 50% for minimum of 48 hours.

ii. Second set in an air circulating oven for 168 hours at 700C and then cooled in a desiccator for minimum of 4 hours.

Gas flow: Set the methane gas flow to 965 ml/min with back pressure 125mm of water. Adjust the flow and air intakes of the burner to get a flame 125mm high and inner blue cone 40mm high.

Flame application: 125mm Bunsen burner flame.

Flame application time: 5 x 5 seconds flame applications with intervals of 5 seconds after each application.


After the 5th application of the flame record the following:

A – Afterflame and afterglow time in seconds.

B – Whether or not the flaming particles ignited the cotton.

C – Burn through (hole formation) of any specimens.

125mm vertical burning test

Based on the measured values use the following table to classify the material as 5VA or 5VB

Test setup:

The Bunsen burner and test specimen were setup as shown in the test schematic.

125mm vertical burning test

bar type test specimens

125mm vertical burning test

plaque type test specimens