What types of non flammable transformer oils are available?

Options marketed as less flammable or fire resistant include natural ester fluids (vegetable based), synthetic esters, and silicone insulating liquids. Esters generally have higher fire points than mineral oil and offer good biodegradability, while silicone liquids are valued for strong fire performance and stable properties in some applications. Selection depends on dielectric requirements, compatibility with materials, operating temperature range, moisture behavior, cost, and environmental constraints. Mineral oil is still common but has lower fire safety margins than these alternatives.