with a bunsen burner and the length of time required for the flame to extinguish after the flame source has burn removed is recorded for each strip unlike the bum test the flame from the burner is held under the laminate for 10 seconds at a time for two cycles a rating is assigned to the sample according to the burn times the v 0 rating which is the best is given when the sum of the two burns on the individual samples is less than or equal to 10 seconds and the sum of the two burns for all five samples is less than or equal to 50 seconds the v 1 rating is given when the sum of the two burns for an individual sample is greater than 10 but less than 30 seconds or if the cumulative burn times for the five samples in the two cycles is greater than 50 seconds but less than 250 seconds higher v ratings are assigned for worse performance the v rating and cumulative burn times are listed for the laminates in table i below the limited oxygen index test gives an indication of the minimum oxygen content needed to support combustion as flammability decreases more oxygen is needed to maintain a combustible fuel source in this test the oxygen content in a controlled atmosphere chamber around the sample is adjusted until combustion occurs the minimum oxygen content that will support combustion is reported as the limited oxygen index loi and is determined via the following equation equ1 furthermore the higher the oxygen content before combustion.