High Performance Phosphate Ester Synthetic Fluid

Mobil Pyrogard™ 53 is a high performance phosphate ester synthetic fluid designed to replace petroleum-based oils in hydraulic applications where operating conditions preclude the use of combustible petroleum products. Mobil Pyrogard 53 is approved by Factory Mutual (FM) as a fire-resistant fluid.

Mobil Pyrogard 53 has excellent resistance to oxidation at temperatures normally encountered in hydraulic systems and gives long service life without the formation of deleterious sludges and other materials. It resists foaming and separates readily from water. It offers good antiwear protection for high pressure, high output hydraulic pumps and is very resistant to shear so that it retains its viscosity throughout its service life. The product provides good long-term rust protection, provided there is proper control to avoid excessive water contamination. Mobil Pyrogard 53 has a specific gravity greater than that of water. Any water in the system will float to the top of the reservoir where it can easily be removed. The high specific gravity also affects the flow characteristics of the fluid and must be taken into account in the design and maintenance of the system.

The successful experience over the years in a wide variety of hydraulic applications where fire resistance is a key concern has made Mobil Pyrogard 53 the product of choice for many users.



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Features and Potential Benefits

Mobil Pyrogard 53 is an important member of the Pyrogard brand of fire-resistant hydraulic fluids that have provided outstanding service, worldwide, in the most demanding of applications. Mobil Pyrogard 53 was developed in conjunction with hydraulic equipment builders to meet the needs of applications where fire-resistance properties are critical, but where the lubrication performance and long service life expected from mineral base products would be maintained.

Mobil Pyrogard 53 is engineered to provide a high level of fire resistance, and is approved as such by the Factory Mutual group. The product is formulated to provide excellent lubrication properties, including resistance to oxidation, sludge formation and foaming, along with long-term corrosion protection and good water separability.

Mobil Pyrogard 53 offers the following benefits:

FeaturesAdvantages and Potential Benefits
Excellent fire resistanceIncreased safety in fire-sensitive applications
Outstanding antiwear propertiesLong life of pumps, motors and valves with reduced parts replacement costs
Excellent oxidation stability and sludge resistanceExtended fluid life and long filter life
Long term rust protection in serviceProblem-free hydraulic system operation, reduced downtime
Highly resistant to viscosity shear breakdownRetains viscosity over life of fluid to give smooth, efficient and reliable operation
Good antifoam and water separation propertiesAvoids excessive water contamination and erratic operation due to foamy oil; lower operational costs



Application considerations: Seal and accumulator bladder materials must be compatible with Mobil Pyrogard 53. Butyl rubber, silicon, Teflon, Viton or equivalent materials are generally satisfactory. In all cases, operating conditions and the variability of elastomer properties from different manufactures should be considered. For best results, consult the equipment supplier or seal manufacturer for specific recommendations.

Many paints, coatings and some plastics are not suitable for use with Mobil Pyrogard 53. The manufacture of the coatings used should be consulted prior to use. When changing from petroleum oil to a phosphate ester fluid it is recommended to completely remove the paint from the reservoir and leave the reservoir unpainted. If this is not possible, clean suction screens frequently to prevent pump cavitation or starvation.

Water-glycol and emulsion-type fluids are not compatible with Mobil Pyrogard 53. Systems must be thoroughly drained and flushed before installing a new charge of Mobil Pyrogard 53.

Mobil Pyrogard 53 is recommended for hydraulic applications where fire resistant type fluids are required. While there may be various possible sources of ignition in many industrial facilities, plants where metals are smelted or hot-worked are perhaps most at risk. Such plants frequently have a history of damage to and leakage from hydraulic system hoses and other components. For safety reasons, Mobil Pyrogard 53 is recommended in these situations. Specific applications include:

  • Aluminum dye casting machines.
  • Tilting systems of cast iron induction melting furnaces.
  • Various steel industry applications where fire hazard is a key concern.

Typical Properties

Mobil Pyrogard 53 
Viscosity, ASTM D 445 
cSt @ 40º C41.8
cSt @ 100º C5.1
Pour Point, ºC, ASTM D 970
Flash Point, ºC, ASTM D 92246
Auto Ignition Point, ºC538
Specific Gravity @ 15.6º C1.155

Health and Safety

Based on available information, this product is not expected to produce adverse effects on health when used for the intended application and the recommendations provided in the Material Safety Data Sheet (MSDS) are followed. MSDS's are available upon request through your sales contract office, or via the Internet. This product should not be used for purposes other than its intended use. If disposing of used product, take care to protect the environment.