A Non-Passive Failure(NPF) is an industry term to define the rupture of a pressurized lamp. There is typically a very high internal operating pressure in Welch Allyn’s gas filled incandescent, halogen incandescent and Solarc high intensity metal halide sources. A rupture of the glass can occur and Welch Allyn refers to this as a non-passive failure. This is term is commonly used by other lamp manufacturers in the lighting industry.