Certain machinery inspections should not be carried out during daylight hours for accuracy reasons.
Surprisingly, it has nothing to do with the state of the surrounding environment being light or dark, but to do with the thermal energy from the sun and the energy emitted from objects in the surrounding environment. This energy is usually significantly lower at night than during sunlight hours.
Even on relatively cool days, heat energy from the sun will be gradually absorbed by buildings, roads, and construction materials while it’s daylight outside.
When these types of objects absorb energy from the environment over the course of the day, any small faults in the objects become less distinguishable from the objects emitted energy which has been inflated due to the absorbed solar energy. This is a phenomenon called “solar loading”.
Unfortunately, people who do not understand thermography often say things like, “We are just inspecting rollers, so we don’t have to be that accurate”.
This way of thinking will eventually lead to an unexpected failure to occur.
It is due to the fact that untrained people do not understand what level of accuracy or inaccuracy IS acceptable for those components.
The exception to the rule is sometimes, if it is very overcast, and it is a fixed plant conveyor or an outdoor electrical component inspection in a power distribution or control system.
Some of the most important reasons that pertain to thermography inspections on a fixed plant are listed below:
I personally performed a test in winter to prove this theory on a plant in Central Queensland, the effect of the rising sun between the eastern and western sides of the conveyor system. I found that within half an hour of the sun striking the conveyor components, there was up to a 10°C temperature differential between the eastern and western sides.
This temperature differential decreased over the day; however, the overall energy absorbed and therefore emitted would cause the following problems with inspections:
If you would like to discuss this topic further, please reach out.
Jeff Erichsen