Test is run with bars one half inch wide and five inches long. These are held vertically and exposed to a laboratory burner flame three quarters of an inch high. Each sample is ignited for ten seconds, the flame allowed to go out, and ignited for a second time of ten seconds. The time taken for the flame to go out is measured and the technician watches for burning char or liquid droplets failing.
To pass UL94V-0 flame must be out in ten seconds or less, no glow beyond thirty seconds, and no burning material can fall.
To pass UL94V-1 flame must be out in thirty seconds or less, no glow beyond sixty seconds, and no burning material can fall.
To pass UL94V-2 flame must be out in thirty seconds or less,
no glow beyond sixty seconds, and burning material can fall.
