Fire-resistant fluid
a fluid difficult to ignite and/or which shows little tendency to propagate flame, used especially in high-temperature or hazardous hydraulic applications. These fluids are less flammable than mineral (petroleum) oil and are approved for fire resistancy by Factory Mutual Research. They will burn at the ignition source but will not propagate a flame back through a spray mist to the leak. They will self-extinguish when the ignition source is removed. Three common types of fire-resistant fluids are:
| water-petroleum oil emulsions | in which the water prevents burning of the petroleum constituent |
| water-glycol fluids | which are essentially non-flammable by nature |
| non-aqueous fluids of low volatility |
such as phosphate esters, silicones, and halogenated hydrocarbons |