Liquid Penetrant Testing Level 2 (PT-2) Practice Exam

What is the minimum warm-up time normally required for a mercury vapour black light?

1. None

2. 2 to 3 minutes

3. 5 minutes

4. 10 minutes

The correct answer is: 5 minutes

The minimum warm-up time required for a mercury vapor black light is typically about 5 minutes. This warm-up period is essential because it allows the lamp to reach optimal operating conditions, ensuring that the ultraviolet (UV) light emitted is at the correct intensity for effective Liquid Penetrant Testing. During the warm-up phase, the mercury inside the lamp vaporizes and establishes a stable arc that produces the necessary wavelengths of UV light, specifically in the range that is most beneficial for detecting penetrants. If the lamp is not warmed up sufficiently, it may not produce enough UV intensity, potentially leading to inadequate inspections and undetected flaws. Other time options, such as none, 2 to 3 minutes, or 10 minutes, do not align with industry practice, as they either fall short of ensuring proper operation or extend beyond what is typically necessary, thus should not be considered standard procedure for warm-up times of this type of lamp.