Mobil Pyrotec HFD 46 is a high performance fire resistant hydraulic fluid. It is designed for use in electro-hydraulic governor control systems of steam turbines, including systems using fine tolerance servo valves. It is also recommended as a fire resistant lubricant in, for example, steam and gas turbines as well as fire resistant hydraulic systems. Mobil Pyrotec HFD 46 is FM approved as a fire resistant industrial fluid.