UL94 foamed material horizontal burning test

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UL94 foamed material horizontal burning test for classifying materials HBF, HF-1 or HF-2.

This test is intended to be performed on foamed plastic materials.


Specimens: Four sets of 5 specimens with nominal dimensions 150mm x 50mm and in minimum and maximum thickness.

Specimen conditioning:

Two sets of 5 specimens per sample were 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: Attach a wing tip to the Bunsen burner, and adjust the gas flow till a clean blue flame 38mm high is obtained.

Flame application: 38mm Bunsen burner flame

Flame application time: 60 seconds.

Measurements for HF-1 and HF-2

A – The flaming ceases (afterflame).

B – The flaming and glowing ceases (afterglow).

C – The flaming or glowing front reaches the 125mm mark or when the specimens ceases burn or glow before 125mm mark.

D- The distance specimen burnt up to 60mm mark or if the 60mm mark passed.

E- The dripping particles ignited the cotton placed below.

Measurements for HBF

A – The duration of burning between the 25mm mark until flaming or glowing stops or passes 125mm mark.

B – The distance the specimen burned in mm between 25mm mark and where the flaming / glowing stops or up to 125mm mark.

C- burning rate expressed in mm/min.

Based on the measured values the specimen is classified HBF if it meets the all of the following conditions:

i. Burning rate C expressed in mm/min is less than 40mm/min over a 100mm span.

ii. Each specimen should cease to burn before flaming or glowing reaches 125mm mark.

Foamed Material Horizontal Burning Test

Based on the measured values use the following table to classify the material as HF-1 or HF-2.

4/5 means 4 specimens out of a set of 5.

1/5 means 1 specimen out of a set of 5.

Test setup:

The Bunsen burner and specimen is arranged as shown in the following test schematic.

Foamed Material Horizontal Burning Test