XL-7335 is a 100% Silicone transformer fluid designed for use as a replacement for PCB (askeral)
filled electric transformers, or as an OEM fill on new equipment.

Small fires involving PCB transformers can result in long-term shutdown of
facilities, loss of business, extensive clean-up costs, and the possibility of
extensive lawsuits. A carefully selected replacement transformer fluid can make
sound business sense in many ways through improved safety of the units, and
higher operating efficiencies.

There exists a vast array of transformers on the market today such as:

• Air Cooled • Mineral Oil
• Dry Type • High Molecular Weight (HMW) Hydrocarbon
• Cast Resin • Chlorinated Hydrocarbon
• Vapour Cooled • Silicone Liquid

Liquid filled transformers are preferred over dry-type and vapour-cooled systems
in medium to large type units because of the following advantages:
• Unlike solids, liquids cool as well as insulate
• More compact than dry-type or cast resin
• High efficiency at reasonable cost
• Liquids do not crack
• Can be operated in harsh surroundings because they are sealed

In addition, XL-7335 SiliconeTransformer Fluid adds the following to the list of advantages:
• Same dielectric strength and temperature stability as PCB’s
• Same performance as PCB’s without environmental hazards attached
• Non toxic (cosmetic grade & food additive) base oil
• May be used in food processing plants, and near waterways
• Highly compatible with most other transformer fluids and construction materials
• Polydimethylsiloxane base is non-solvent and chemically inert
• Will not sludge or break down
• Longer transformer life, with reduced maintenance

XL-7335 is hard to ignite, gives off less heat and smoke when it does burn, and virtually
extinguishes itself when the external source of heat is removed. Tests have also
shown that the combustion by products are significantly lower than that of other
transformer coolants.

Because heat generated by a fire contributes to its spread and hampers fire
fighting efforts, the amount of heat released by a material as it burns is an
important factor in assessing the potential fire hazard. XL-7335 proved
in tests performed that it produced the lowest heat release rates of the liquids

The constitution of XL-7335 is a pure liquid without any stabilizers, pour point suppressants or other
additives found in comparable mineral oils. The inherent high chemical
stability, and ‘water-white’ clarity of XL-7335 permits
simple visual checks for foreign materials in the field.

XL-7335 intrinsically provides the same high dielectric properties as hydrocarbon fluids with the
added dimension of exceptional thermal, electrical and chemical stability. This
results in a product that will NOT break down and form acids that will attack
and corrode the insulation and solid components.

The main source of heat transfer in liquid filled transformers are by convective
forces, though conductive and radiative forces also help remove the heat from
the transformer core. The convective effect occurs when fluid heated by the hot
windings and core rises, and the heavier cool fluid sinks downward. This
circulation of fluid carries heat to the transformer case and cools the windings
without additional equipment. XL-7335 is
comparable to askerals in heat transfer ability, and its density change with
respect to heat is far greater than hydrocarbons thus resulting in a highly
efficient ‘thermal syphon’ and greater cooling ability.

Product Code: XL-7335

Dielectric Strength (KV @ 25°C) (ASTM D-877) 40
Dielectric Constant (@ 25°C) (ASTM D-924) 2.7
Volume Resistivity (ohm cm 25°C) (ASTM D-1169 1 x 1015
Dissipation Factor (@ 25°C) (ASTM D-924) 0.00002
Dissipation Factor (@ 100°C) (ASTM D-924 0.00004
Flash Point (°C) (ASTM D-92) 300
Fire Point (°C) (ASTM D-92) 343
Pour Point (°C) (ASTM D-97) -55
Thermal Conductivity (Cal/[Sec cm2

°C]/cm) (ASTM D-2717)
Specific Heat (Cal/gm/°C) (ASTM D-2766) 0.365
Coefficient of Expansion (OC/0°C/°C) (ASTM D-1903) 0.00104
Rate of Heat Release – Convective (kW/m2) 62
Rate of Heat Release – Radiative (kW/m2) 30
Chemical Name Polydimethyl-siloxane
Chemical Structure [(CH2)2SiO]Y(CH3)2
Specific Gravity (g/ml @ 25°C) (ASTM D-1810) 0.960
Interfacial Tension (dyne/cm @°C) 20.8
Viscosity (cSt @ 25°C) (ASTM D-88) 50
Viscosity (cSt @ 50°C) (ASTM D-88) 32
Smoke Release Rate (cfm/ft2L)
(ASTM E-906 [OSU])
Weight Loss (% [burn time, min]) – Smoldering 1 [40]
Weight Loss (% [burn time min]) – Flaming 16 [13]
Gases evolved during combustion SiO2,
CO, CO2,




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