Q&A

UL94 flammability test methods include UL94 HB, UL94 V-0, UL94 V-1, UL94 V-2, UL94 5VA and UL94 5VB, which cover most of the flammability of ABS resin. Please see below for an image of the test method.

UL94 Test Method

The test methods introduced here are simplified images. If you would like more information on how the tests are carried out and the pass/fail results, please contact us by email.

---

UL94 HB Standard

A rectangular test piece is placed horizontally and burned, and the pass/fail is judged based on the speed at which the combustion progresses. There are two standards, 40mm/min and 75mm/min, depending on the thickness of the test piece.
 

Flame contact	HB

---

UL94 V-0, V-1, V-2 standards

The test methods are the same for V-0, V-1, and V-2.
The test is performed using five test pieces. As shown in the figure, a burner flame is applied to the bottom end of a vertically supported rectangular test piece for 10 seconds, and then the burner flame is removed from the test piece. When the flame goes out, the burner flame is immediately applied for another 10 seconds, and then the burner flame is removed.

The V-0, V-1, and V-2 ratings are based on the duration of flaming combustion after the first and second flame contact, the total duration of flaming combustion and flameless combustion after the second flame contact, the total flaming combustion time of the five test pieces, and the presence or absence of burning drips. For both the first and second flame contacts, V-0 means flaming combustion must end within 10 seconds, and for V-1 and V-2, it must end within 30 seconds.
Furthermore, the total duration of the second flaming burn and the flameless burn time must be extinguished within 30 seconds for V-0 and within 60 seconds for V-1 and V-2. The total duration of the flaming burn of the five test pieces must be within 50 seconds for V-0 and within 250 seconds for V-1 and V-2. Combustion falling objects are only allowed for V-2. All test pieces must not burn out.
 

Flame contact	V-0	V-1	V-2

---

UL94 5VA/5VB standard

5VA and 5VB are the highest flammability classes , determined using a burner flame with approximately 10 times the combustion energy of the V-0, V-1, and V-2 tests. The test methods for 5VA and 5VB are the same, and are determined by both the Bar (strip test piece) test and the Plaque (plate test piece) test. The flame retardant performance standards for the Bar (strip test piece) test are the same, but the determination of holes in the Plaque (plate test piece) test is as follows:

5VA: No openings,
5VB: Openings are acceptable

5VA and 5VB are sometimes collectively called 5V, but actual applications of electrical products that require 5V include large equipment and stationary equipment. These devices basically require a combustion performance of 5VA, but 5VB is only applicable to some of these applications (office equipment, information processing equipment, etc.).

 

1) Bar Test	5VB

 

2) Plaque Test (applies to those who have passed the Bar Test)

No opening

With opening