Question

Which fluid is NOT used in hydraulic systems?

• A. Petroleum based oils
• B. Water
• C. Compressed air
• D. Molten metal

Answer 1

Answer:

C. Compressed air

Compressed air is not used in hydraulic systems. Hydraulic systems use a liquid as a pressure medium while pneumatic systems use a gas. Various liquids can be used, including water, mineral oils, synthetic and organic liquids, vegetable oils, and even molten metals.