Glow Wire Thermo Resistance Loop VRI SP u type for Hot-wire ignition test

Specification:

1,Glow-wire material: Nickel/Chromium (>77%Ni/20±1%Cr)

2, Diameter: 4,0 mm ± 0,07 mm (before bending)

3, Dimension A: (after bending) see 5.1

Characteristics of Resistance:

Appliance:

The tip of the glow-wire is then brought smoothly into contact with the test specimen for a duration of 30 s ± 1 s. An approximate rate of approach and withdrawal of 10 mm/s to 25 mm/s has been found to be satisfactory. However, the rate of approach shall be reduced to near zero upon contact to avoid impact forces exceeding 1,05 N. In those cases where the material melts away from the glow-wire, the glow-wire shall not be kept in contact with the test specimen. Following the application time, the glow-wire and the test specimen are slowly separated, avoiding any further heating of the test specimen and any movement of air which might affect the result of the test. The penetration of the tip of the glow-wire into and through the test specimen shall be limited to 7 mm ± 0,5 mm.

When forming the glow-wire , care shall be taken to avoid fine cracking at the tip.

 NOTE:

 Annealing is a suitable process for prevention of fine cracking at the tip.