Air Contamination in Oil and Its Solutions

It is a well-known fact that particulate and water contamination are often found in lubrication, hydraulic and dielectric oil systems. However, air and gases, as another kind of contamination, is usually neglected, despite the fact that it can potentially degrade the oil and damage the equipment components. Although no measures can eliminate air completely from oil, there are indeed methods to minimize its presence.
Air in oil can be divided into three types:
Dissolved Air: This type of air cannot be seen by human eyes and since practically, it does almost no harm to oil, there's little need to detect and expel them.
Entrained Air: Most harmful and requires suitable treatment. When your oil contains entrained air, it looks cloudy. Whether the emulsification is caused by air or water can be identified by a simple test. Taking a bottle of sample oil and leave it stand for a while, observing whether it clears up over time. If the oil clears up with the formation of an aqueous layer, the cloudiness is due to water contamination, otherwise, you have entrained air problem to deal with.
Foam: This type of air appears as a stable layer of comparatively big bubbles that build up on the surface of oil. A foam layer usually gives clear evidence that quite a mount of entrained air is in the oil.
Like I said before, it may be impossible to completely remove air from your oil, but measures should be taken to reduce it as much as possible. Excluding excessive air gives more life to your oil, improves system efficiency, and reduces wear and deposits. Always keep in mind that oil contamination control is not just remove solid dirt and moisture. It also requires expelling air from the system.
Insulating fluid system is the most sensitive under high voltage, and at present, the most effective means to repel air is transformer oil purification machine. The equipment process oil by vacuum dehydration and degassing, and can effectively eliminate air and various kind of gases from oil.
Welcome thoughts on the subject, and looking forward to discussing with your guys.