Time and again, we hear the same story. Firefighters wait hours until a blazing transformer is de-energized. All they can do is protect adjacent structures or equipment. After the power is turned off, they try to extinguish the fire with foam. When that fails, they try powder, but it reignites. Why?
The aging transformers in the US are failing at a rapid pace and can contain large amounts of mineral oil used to cool the transformer, plus they are huge masses of metal, that retain heat. Foam does very little to cool the transformer and since this is a three-dimensional fire, foam can’t form a blanket.
Remember, NFPA 11, Annex A.1.1. – “Foam is not suitable for three-dimensional flowing liquid fuel fires or for gas fires.”
￼Next, they try powder, but powder also doesn’t cool. As long as the oil is above the autoignition temperature of the oil, the fire will reignite.
The proven solution is F-500 Encapsulator Agent. It rapidly cools the oil and metal and encapsulates the oil, rendering it nonflammable. After F-500 EA extinguished a fire in Queens, NY in less than two minutes, ConEdison began extensive testing and found F-500 EA was the only agent that could be safely applied to an energized transformer (up to 345 kV, streaming from 125 feet).
Details of a recent transformer fire are described in the Linked pdf flyer.