Water-glycol solution is suitable for hydraulic systems requiring fire protection. If the liquid is operated at a temperature higher than 65 "C for a long time, the evaporation of water makes its viscosity increase, so it must be checked frequently. The viscosity is low at low temperatures, and its lubricity is worse than petroleum-based hydraulic oil. Most rubber seal materials used in the system are compatible, but will cause a lot of paint to come off.