Cable Vertical Combustion Test machine UL1581 VW-1
I. Product Overview
The VW-1 Cable Horizontal and Vertical Flame Tester is a precision
test instrument designed to evaluate the flame retardancy of wires,
cables, electrical accessories, and other solid materials. Its core
purpose is to simulate the burning behavior, flame spread, and
self-extinguishing properties of materials exposed to a small flame
under specific conditions.
"VW-1" is a flame-retardant rating designation derived from the UL
standard, standing for "Vertical Wire-1." The instrument precisely
controls the timing, angle, and position of the flame application
to determine whether the tested sample meets the requirements of
VW-1 or other similar flame retardancy ratings (such as FT1 and
FT2).
This instrument is an essential testing instrument for quality
control and product certification (such as UL and CSA) in the wire
and cable, electronics, and building materials industries.
II. Test Principle
The basic principle of the test is to secure a sample (cable) of
specific dimensions at a specified angle (usually 20° or 90°
perpendicular) in a test chamber. A flame of a specified height and
heat is generated using a standardized Bunsen burner (or a
specialized blowtorch). The flame is applied to the lower surface
of the sample for a specified time (e.g., 15 seconds). The flame is
then removed, and the following behaviors of the sample are
observed and recorded:
Afterflame Time: The duration the sample continues to burn after
the flame is removed.
Afterglow Time: The duration for which the sample remains hot after
the flame is extinguished.
Charred Length/Scorch Length: The maximum length of the sample that
is burned or damaged.
Ignition of Cotton Bedding: During the test, the flame drippings
ignite the dry absorbent cotton pads below, which simulate the
environment.
Based on these observations and compared against the criteria
specified in the standard, the flame retardancy rating of the
sample is assessed.
III. Standard Compliance
This equipment is designed to strictly adhere to the following
mainstream international and regional standards:
UL 2556: Test Methods for Wire and Cable
VW-1 (Vertical-Wire 1): One of the most stringent flame retardancy ratings for cables,
requiring that after five flame applications, the afterflame
duration of each test sample must not exceed 60 seconds, and the
bedding must not ignite.
FT1 (Flame Test 1): Similar to VW-1, but with a 20° angle.
FT2 (Flame Test 2): Lower requirements than FT1, requiring a horizontal flame test.
IV. Main Features
Test Chamber:
- This test chamber is constructed of assembled steel plates and
features an anti-static paint finish for an attractive appearance
and rust and corrosion resistance. A smoke exhaust system is
installed on the top of the chamber to discharge exhaust gases
outdoors after the test. Two air inlets are located on the lower
sides, along with a set of pneumatic seals.
- An observation window is located on the front of the chamber for
easy observation of the test progress.
- Ventilation System: An exhaust vent is located on the top, allowing
connection to an external exhaust system to promptly remove toxic
and hazardous gases generated by combustion.
Sample Fixture:
- Test Stands: VW-1 and FT2 Combustion Test Stands.
- The fixture design ensures a secure hold on the sample without
interfering with test results.
Burner System:
- The burner is imported from Hamburg, USA, meeting ASTM D 5025-99
requirements, with a standard power of 500W and a 20° angle.
- Gas Supply: High-purity methane or propane is used as fuel, and a
U-tube pressure gauge and high-precision flow meter are provided to
ensure stable and adjustable gas flow and pressure. Flame height
scale: used to quickly calibrate the flame to the required standard
height (such as 125mm).
