STO-50 Silicone Transformer Oil

Chemical Name: Linear Polydimethylsiloxane (PDMS)

CAS No: 63148-62-9

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Availability:5 - gallonpail(20kgnetwt.), 55 - gallondrum(200kgnetwt.)

Product Equivalent: XiameterPMX® - 561DC561®,GESF97 - 50,MomentiveSF97 - 50,WackerTR - 50

STO-50 Silicone Transformer Oil is a 100% Polydimethylsiloxane silicone oil (CAS# 63148-62-9) with a viscosity of 50cSt (centistoke) @ 25°C. STO-50 Silicone Transformer Oil is formulated exclusively for use as a dielectric fluid and dielectric coolant in high voltage transformers transformers.

STO-50 Silicone Transformer Oil is characterized by its high dielectric strength, high flash point, wide service temperature range, , low vapor pressure, good heat capacity values, low pour point, low viscosity change at extremely high and low temperatures, and inertness to virtually all substrates. It is a 100% PDMS silicone fluid that contains no additives (such as thermal stabilizers).

Unlike conventional PDMS Silicone fluids, STO-50 is dehydrated to contain < 50ppm water content to ensure the highest degree of dielectric strength and stability.

STO-50 Silicone Transformer Oil is an environmentally safe replacement for PCB containing askarels as the dielectric coolant for liquid-filled transformers. Its high thermal stability makes it a good choice for transformers that are located indoors or next to buildings where a thermally stable fluid is more critical.

Features and Benefits

  • High dielectric strength fluid
  • High flash point > 300°minimal flammability and high temperature stability
  • Low Viscosity change, low volatility
  • High thermal oxidation resistance
  • Chemically inert
  • Low toxicity
  • Compatible with most existing transformer insulation systems
  • Environmentally superior alternative to PCB's as transformer fluid
  • Longer service life than conventional transformer oils

Typical Properties:

Parameter Unit: Value:
Appearance Crystal clear fluid
Density @ 25°C kg/dm3 .96M
Viscosity @ 25°C mm2 sec 50(cSt)
Water content ppm 50
Refractive Index 1.404

Electrical Properties:

Parameter Unit: Value:
Dielectric Breakdown voltage kV 50M
Permittivity @25°C, 50Hz 2.7
Dissipation factor @25C,50Hz 0.0001
Volume resistivity @ 25C ohm.cm ohm.cm 1.0 x 1014

Thermal properties:

Parameter Unit: Value:
Flash point (open cup) >300°C
>572°F
Fire point (open cup) 370°C
698°F
Specific heat KJ/kg.K 1.51
Specific heat cal/gm°C 3.7x10-4
Thermal conductivity W (m.K) 0.151
Oxygen index TDLOI 21.4
Coefficient of Expansion cc/cc/°C 10.55 x 10-4

Applications Include

  • High Temperature Laboratory Bath Fluid
  • Excellent dielectric coolant
  • Dielectric silicone bath fluid
  • High Temp /High Pressure Fluid
  • High Temperature Fluids for Flow Control Fluid
  • High Temperature Calibration Fluid
  • Refractive Index Matching Fluid
  • Silicone damping fluid for electrical equipment and gauges
  • High Temp Silicone Lubricant for Plastic Parts
  • Silicone Lubricants for Rubber Parts

IEC & ASTM Specifications:

STO-50Silicone Transformer Oil meets bothInternational Electrotechnical Commission IEC 836 "Specifications for silicone liquid for electrical purposes" (Silicone Fluid Type T-1) and
ASTM D 4652 "Silicone Fluids for Electrical Insulation specifications for repair or top-off of existing liquid-filled units. These standards cover both the physical and electrical properties of fluid suitable for dielectric applications.

STO-50 has a fire point exceeding the requirements of these documents and is within the IEC 1100 class with lowest heat of combustion. Silicone Transformer Oil presents a much lower fire hazard than other transformer fluids. It is difficult to ignite, but if ignited, it will produce less heat and smoke. It will virtually extinguish itself when external heat source is removed.

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.