eli5: If water is non-compressible, then why not use it in hydraulic machines instead of hydraulic oil?

Question

eli5: If water is non-compressible, then why not use it in hydraulic machines instead of hydraulic oil?

In: 1817

Answer 1

Basically, water has some nasty properties. It doesn’t lubricate, it promotes corrosion, it has a low boiling point, and if it freezes it breaks stuff.

There are a few places where its other properties are valuable enough to make up for its nasty properties, typically in food processing plants and in steel mills. It’s non-toxic, so a leak into food won’t kill anyone, and it’s nonflammable, so a leak onto red-hot steel won’t start a fire.