Mobil Pyrotec™ HFD 46B

Fire-Resistant Hydraulic Fluid

Mobil Pyrotec™ HFD 46B is a high performance phosphate ester self-extinguishing fire resistant hydraulic fluid. Mobil Pyrotec HFD 46B is TXP-free.


Mobil Pyrotec HFD 46B has been evaluated in stringent tests for fire resistance such as the ISO 20823 manifold ignition test. Compared to other types of synthetic or mineral fire resistant fluids, Mobil Pyrotec HFD 46B shows a much higher ignition temperature (greater than 700°C) and is very difficult to ignite. If ignited, the flame will self-extinguish.


Mobil Pyrotec HFD 46B is formulated from specially purified phosphate base stocks and additives providing improved oxidation stability and lubrication properties. Physical properties such as foaming, air release and demulsibility are controlled to meet the limits specified by turbine manufacturers.



Features and Benefits


Advantages and Potential Benefits

High ignition temperature and self-extinguishing capability, approved by FM Approvals

Preferred choice in applications where fire safety is critical

TXP-free formulation

Compliance with future safety, health and environment regulations

Excellent oxidation resistance

Helps to extend oil life

Excellent anti-wear properties

Helps to extend component life



Mobil Pyrotec HFD 46B is recommended for use in applications where fire safety is critical, such as:


     •  Electro-hydraulic governor control systems of steam turbines, especially where a high performance fluid is required,

     •  Hydraulic and oil circulation systems operating in conditions subject to fire hazards,

     •  Other applications such as gas turbines, turbo-compressors, reactor coolant pumps and generators.


Please note that Mobil Pyrotec HFD 46B is fully compatible with Mobil Pyrotec HFD 46.


Special precautions should be taken when using Mobil Pyrotec HFD 46B regarding:


     •  System operating temperatures: normal system temperature should be between 50 and 65°C to avoid water condensation and local spot temperatures should be kept below 150°C,

     •  Flushing procedure when replacing  petroleum oils, conventional soluble emulsions, water in oil emulsions or water glycol fluids,

     •  Compatibility with elastomers (for example, Mobil Pyrotec HFD 46B is not recommended for use with Neoprene, nitrile and silicon materials but compatible with seals and hose materials such as butyl rubber and Viton),

     •  Compatibility with paints, enamels and varnishes (for example, Mobil Pyrotec HFD 46B is not recommended for acrylic, latex and phenolic resin paints but compatible for example with epoxy type paints).


Please contact your your ExxonMobil representative for further details.

Specifications and Approvals

This product has the following approvals:

FM Global Approvals Class 6930

Siemens TLV 9012 02

Siemens TLV 9012 03

Mitsubishi Power Ltd MS04-MA-CL004(Rev.6)


This product meets or exceeds the requirements of:

GE Power GEK 46357H


Properties and Specifications




ISO 46

Kinematic Viscosity @ 40C, mm2/s, ISO 3104


Flash Point, Cleveland Open Cup, °C, ISO 2592


Foam Sequence II, Tendency, ml, ISO6247


Foam Sequence II, Stability, ml, ISO6247


Water Separability, min, ISO 6614


Total Acid Number, mgKOH/g, ISO 6619


Volume Resistivity 20C, MOhm.m, IEC 60247


Water, wt %, ISO 760


Chlorine, ppm, IP 510/04


Appearance, Visual


Particle Count, Rating, ISO 4406

-/15/12 (max)


Health and safety

Health and Safety recommendations for this product can be found on the Material Safety Data Sheet (MSDS) @