DPDM-400 Diphenyl-Dimethyl Silicone Fluid

Product Description: PM‐125 Silicone Fluid is a clear, colorless and odorless Diphenyl‐Dimethylsiloxane Silicone Oil with a viscosity of 400cSt @ 25°C. It replaces methyl groups found in conventional PDMS Silicone oils with a high percentage of Diphenyl groups. In doing so, thermal stability and resistance to oxidation are significantly increased. DPDM‐400 provides long term stability at 250°C (open to air) and 300°C (closed to air). The fluid is further characterized by its high flash point, high dielectric strength, stability at extreme pressures, good heat capacity values, excellent lubricity and inertness to virtually all substrates.

Chemical Name: Diphenyl-Dimethylsiloxane

CAS No: 8083-14-7

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Service Temperature Range: 25°C to 250°C open to air / 25°C to 300°C closed to air

Availability: 1‐gallon (4kg net wt.), 5‐gallon pail (20kg net wt.), 55‐gallon drum (200kg net wt.)

In comparison to conventional PDMS silicone oils, DPDM‐400 has much higher thermal stability and remains stable at temperatures > 250°C (open system). When heated, its viscosity lowers very quickly which makes it an excellent choice for high temperature laboratory baths and heat transfer systems that have to circulate and pump the fluid. Conversely, it is not recommended for cold temperature systems due to its acute viscosity increase at lower temps.

As a calibration fluid, DPDM‐400 Silicone Fluid is widely used in Flow Control, Temperature Control and Motion Control technologies. Again, its advantage over conventional oils is that it will not break down at high temperatures and it will not coagulate at high pressures. It is widely used for instruments, gauges, sensors, meters and devices that are subject to extreme temperatures and high pressures.

DPDM‐400 Silicone Fluid has a higher RI value (1.505) than conventional PDMS silicone. It an excellent RI index matching fluid and optical fluid for use in sensor /imaging / LED and Photonics technologies that require a higher RI value than conventional fluids.

Typical Product Data:

Viscosity @ 25°C Specific Gravity Viscosity Temp Coefficient Pour Point °C Flashpoint °C Refractive Index Surface Tension
400cSt 1.07 0.82 -30°C 315°C 1.505 25.2

Thermal Properties:

Thermal Conductivity @ 50°C cal/cm•sec• °C Thermal Expansion cc/cc °C Specific Heat cal/g/ °C , 25°C
0.00032 0.00073 0.35

Thermal Gel Times (open system)

@ 250°C @ 260°C
1,500 to 2,000 hours >200 hours

Dielectric Properties:

Breakdown Voltage KV/2.5mm Dielectric constant (50Hz) @ Dissipation Factor (50Hz)
>50 2.88 <0.0005

Viscosity/Temp Coefficient: 0.82

Viscosity @ 25°C: 400cSt (mm2/sec)

Viscosity to Temperature:

Temperature Viscosity (mm2/sec)
@ 250°C 7cSt(mm2/sec)
@ 200°C 11cSt(mm2/sec)
@ 100°C 46cSt(mm2/sec)
@ 50°C 167cSt(mm2/sec)
@ 25°C 400cSt(mm2/sec)
@ 0°C 1,770cSt(mm2/sec)
@ -25°C 24,800cSt(mm2/sec)


  • High Flash Point
  • High thermal Stability
  • Viscosity lowers quickly when heated:
  • Easy to pump/circulate at elevated temps
  • High Refractive Index RI 1.505
  • High Dielectric Strength
  • Hydrophobic
  • Stable under high rates of pressure
  • Stable under high rates of shear
  • Excellent Lubricity

Applications Include:

  • High Temperature Laboratory Bath Fluid
  • High Temperature Heat Transfer Fluid
  • High Temperature Dielectric Fluid
  • High Temp /High Pressure Fluid
  • High Temperature Fluids for Flow Control Fluid
  • High Temperature Calibration Fluid
  • Refractive Index Matching Fluid
  • High RI Matching Fluids for LED and Optics
  • High Temp Silicone Lubricants for Plastic Parts
  • Silicone Lubricants for Rubber Parts

Industries & Fields of Research include: R&D, Education, Defense, Oil & Gas Exploration, Energy, Aviation, Aerospace, Life Sciences, Renewable Energies, Turbine Technology, Wind Power Technology, Temperature Control Technologies, Geothermal, Solar Industry, Sensor Technology, Geosciences, Electronics, Environmental, Electrical Testing, Optics, LED, Photonics, MEMS Technology, Refractive Index Matching Digital Display Technology, Flow Control, Flow Meters, Deep Sea / Subsea Technologies, Dielectric Fluids for Wire & Cable, Deepwater, ROV Technologies, Laser Technology Research, Earth & Atmospheric Sciences, Seismic Research, Oceanography Research, Physical Sciences, Chemical Engineering, Mechanical Engineering, 3D Printing Technology, Plasma Research, LCD Technologies, Polymer Research, Computer Engineering Research, Robotics Research, Plastic Manufacturing, Rubber Manufacturing, Hydraulics, Nanotechnology Research, Geothermal, Fuel Cell Technology, Hydrophobic Coatings, Lighting Systems, Seismology, Aeronautics, Pipe & Tubing Systems, Printing Industry, Industrial Cleaning, Touch Screen Technology, Fiber Optics, Touch Monitor Technology, Touch Screen Technology, Temperature and Process Controllers

Environmental: Silicone Fluids are exempt from Federal VOC regulations, including California (CARB) and OTC regulations. They are HAP‐free and do not contribute to ozone‐depletion and global warming. In addition, they meet RoHS Compliancy.