Conoco FC Fluid-D is a water-glycol based fire-resistant hydraulic fluid developed for use in hydraulic systems operating at 2000 to 3000 psi in areas subject to fire hazards. It can withstand intermittent pressure spikes up to 5000 psi. It contains sufficient water to snuff out a fire resulting from ignition of a fluid leak.

FC Fluid-D is formulated with 60% diethylene glycol and 40% water. It is fortified with additives that provide lubricity, wear protection and corrosion protection for extended life of hydraulic system components. It contains less than 60 parts per billion (ppb) phenols, and does not contain any nitrites or nitrosamines.

FC Fluid-D has good antiwear properties to ensure long life for hydraulic pumps and motors. Special rust and corrosion inhibitors provide corrosion protection in both the liquid phase and the vapor phase. This product is compatible with other water-glycol type fire-resistant fluids.

FC Fluid-D is compatible with most hydraulic pump types, including vane, piston and gear pumps. It is safe to use with most packing and seal materials except polyurethane and silicone. Cork shaft seals should be replaced with Buna N or another synthetic rubber. Leather packing should be avoided and zinc or cadmium-plated components should not be used.

Caution: FC Fluid-D should not be used in systems where operating temperatures exceed 175 ºF (79 ºC). This product contains water and should not be stored at temperatures over 130 ºF (54 ºC). In addition, this product is not recommended for use as a conventional antifreeze coolant for automotive or industrial applications.
Unit of Measure


ISO Grade

N/A 32/46

Density @ 15.6 ºC (60 ºF)

N/A 1.08 g/cm³9.01 lbs/gal
Color1 N/A Red

Freezing Point

N/A -55 ºC-48 ºF

Viscosity @ 40ºC

N/A 39.3 cSt

Viscosity @ 100ºC

N/A 8.5 cSt

Viscosity @ 100ºF

N/A 198 SUS

Viscosity @ 210ºF

N/A 54.7 SUS

Viscosity Index

N/A 185

Alkalinity Reserve

N/A 210
Four-Ball Wear Scar Diameter2 N/A 0.48 mm

pH (neat)

N/A 9.7
Rust Test3 N/A Pass

Water Content Wt.

N/A 40 %


N/A Hydraulic systems operating in areas subject to fire hazards, such as:

  • Steel mills, aluminum mills and foundries
  • Molding and metal die-casting machinery
  • Welding machines
  • Furnace charging equipment
  • Open hearth and basic oxygen furnace (B.O.F.) equipment
  • Power transmission plants
  • Underground mines
FC Fluid-D meets the performance requirements of:
  • Denison HF-4 Hydraulic Fluid - Water Glycols
  • Factory mutual group I fluid
  • Ford M6C1C
  • U.S. Steel 171, Water-Glycol Fluids



  • Fire resistant for safety
  • Excellent wear protection
  • Excellent rust and corrosion protection
  • Good foam resistance
  • Glycol content protects against freezing
  • Compatible with other water-glycol fluids
  • Dyed red color for easy identification

Health and Safety Information

N/A For recommendations on safe handling and use of this product, please refer to the Material Safety Data Sheet via

Care and Maintenance

N/A All water-containing fire-resistant fluids require close maintenance of the water content to ensure safe operation. To keep FC Fluid-D operating at maximum efficiency, the water content and alkalinity level (pH) should be checked routinely and adjusted as necessary to maintain good fire resistance, corrosion protection and proper viscosity.

Water content can be determined with the use of a refractometer and Brix scale provided by the refractometer manufacturer, or by Karl Fisher titration. Digital refractometers are available that will give a direct reading of the water content. The viscosity of the fluid is an indirect measure of the water content of the fluid. Table 1 below shows the amounts of water or glycol to be added at different viscosities to maintain the proper water content for FC Fluid-D.

Alkalinity is determined by measuring the pH of the fluid. The pH should be adjusted as necessary to maintain a pH level of 9.6. Alkalinity may be adjusted by adding small amounts of morpholine to the make-up water.

Ordering Information

Package Type

N/A 55G RD

Pricing Information

N/A Price/Gal

Shipping Note

N/A Shipping will be quoted upon receipt of your order.

  • 1 Test-Visual
  • 2 ASTM D-4172
  • 3 ASTM D-665 A&B