UL 94 is defined as the "Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances testing". This plastics flammability standard is issued by Underwriters Laboratories of the USA.
The standard classifies plastics according to how they burn in various orientations and thicknesses. From the lowest (least flame-retardant) to the highest (most flame-retardant). The classifications are summarised below.
UL 94 HB:
Slow burning on a horizontal specimen; burning rate < 76 mm/min for thickness < 3 mm and burning stops before 100 mm.
Unless listed below, most OKW products carry this rating. Please see individual product pages for details.
UL 94 V-2:
The test samples are extinguished within 25 seconds average time (mean of 10 successive tests). None of the test samples burn longer than 30 seconds. The test samples emit some burning particles.
UL 94 V-1:
The test samples are extinguished within 25 seconds average time (mean of 10 successive tests). None of the test samples burn longer than 30 seconds. None of the test samples emit burning particles.
UL 94 V-0:
The test samples are extinguished within 5 seconds average time (mean of 10 successive tests). None of the test samples burn longer than 10 seconds. None of the test samples emit burning particles.
UL94 5VB:
Burning of the test sample stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may develop a hole.
UL94 5VA:
Burning of the test sample stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may not develop a hole.
