Determining the oxygen index is the most important fire protection test for electromechanical and electronic components besides the smoke toxicity and smoke density test. This test procedure determines the lowest oxygen concentration of an ambient atmosphere that is required for a material to continue burning independently under specified conditions. Burn durations (<180 s) and burn path (<80 mm) are monitored.
The un-reinforced polyamides used for Phoenix Contact terminal blocks with flammability rating UL 94 V0 achieve an oxygen index > 32%. These excellent results are responsible for achieving outstanding ratings and classifications, for the expiring national standards as well as the European standard EN 45545-2.
The UL 94 standard (harmonized with the test regulations according to EN 60695-11-10) describes inflammability tests that have gained particular importance in the field of electrical engineering. Behavior in fire is the main focus. Items are classified according to either UL 94 HB (Horizontal Burning) or UL 94 V (Vertical Burning). The test setup is such that the UL V0/1/2 classifications are stricter than the 94 HB classification.
UL 94 V0/1/2
After conditioning, the test bar is vertically clamped and flame-treated several times for ten seconds each time. Between the flame treatments, the time until the test bar is extinguished is measured. Afterwards, the afterburning times and the drip behavior are evaluated.
The plastics used for Phoenix Contact terminal blocks achieve the highest rating, UL 94 V0, for the vertical test with a panel thickness of 0.25 mm.
|UL 94 V0||UL 94 V1||UL 94 V2|
|Burning time after each flame treatment||≤ 10 s||≤ 30 s||≤ 30 s|
|Total burning time after 10 flame treatments||≤ 50 s||≤ 250 s||≤ 250 s|
|Glowing time after the 2nd flame treatment||≤ 30 s||≤ 60 s||≤ 60 s|
|Ignition of the absorbent cotton under the sample||No||No||Yes|