Is air bag (also known as: membrane, compensator, diaphragm, baloon) necesssary for conservator type medium power transformer?

Air bag application seperates the contact between the transformer oil and air in the atmosphere. By using the airbag, the transformer becomes like a hermetically sealed transformer. The oil lifespan can increase since it's not in contact with air in the atmosphere. But for the transformers without the airbag, when periodic maintenance is done on the dehydrating breather the transformer oil will not be effected from the air in atmosphere.

Released for: Schneider Electric USA