UL 94, the Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances testing, is a plastics flammability standard released by Underwriters Laboratories of the United States. [1]

What is UL 94? UL 94 is a safety standard to determine the flammability of plastic materials. This test is released by Underwriters Laboratories of the United States. It measures: The ability of the plastic part to extinguish or spread the flame after ignition.

UL 94 H-B Horizontal Burn; Slow horizontal burn test (H-B) are considered "self-extinguishing". The lowest (least flame retardant) UL94 rating.

Jul 15, 2019 · Two UL 94 ratings that code officials commonly run across are HB and V (V-0, V-1, or V-2). These ratings are established using small-scale tests in which approximately 5 by ½ inch samples are subject to a ¾ inch, 50W tirrel burner flame ignition source.

Flammability UL 94 HB - Horizontal Burning The horizontal burning test is used to determine the HB flammability rating of a material. The flammability rating is calculated for a test specimen as a function of the burning rate and taking account of the material thickness.

Jun 9, 2021 · UL 94 flammability testing ranks plastics according to their ability to ward off ignition, remain consistent in high temperatures, and produce flammable plastic drippings. Since actual fire conditions are unpredictable, UL 94 flammability does not reflect how a …

The UL 94 HB rating is the lowest level of flame resistance. It is assigned to plastics that burn slowly in a horizontal position. For a material to pass this test, it must have a burning rate lower than 76 mm/min if it is thinner than 3 mm, or extinguish before reaching 100 mm.

HB: The lowest fire rating in the UL94 flammability standard. It is required that for specimens with a thickness of 3-13mm, burn rate should be less than 40mm per minute; and for specimens with a thickness of less than 3mm, burn rate is less than 70mm per minute, or flame is extinguished before the 100mm mark.

Mar 1, 2019 · What is UL 94? UL 94 is a plastics flammability standard released by the Underwriters Laboratories (USA). The standard classifies plastics according to how they burn in various orientations and part thicknesses from the lowest flame-retardant to most flame-retardant in six different classifications.

HB testing is generally considered the easiest flammability test to pass and is the lowest and least flame-retardant UL 94 rating. A UL 94 HB rating would typically be acceptable for portable, attended, intermittent-duty, household-use appliance enclosures (e.g. hair dryers).