Submer’s PAO2-Nano Oil Validation
Full qualification of Synano’s PAO-2 nano-oil under the Submer Fluid Validation Program: dielectric strength, fire safety, material compatibility and system-level thermal performance
Synano PAO2-Nano went through independent immersion cooling fluid validation with Submer, the qualification framework used to clear fluids for data center deployment. It passed every acceptance criterion. Breakdown voltage measured 71.4 kV against a 30 kV threshold, closed cup flash point 164.8 °C against a 150 °C minimum, and 14 of 15 material groups performed at or above their predicted result after 336 hours at 80 °C. On an Intel LGA7529 test vehicle, thermal performance matched the PAO-2 base oil in every cooling configuration tested. Submer confirmed the fluid suitable for deployment in immersion cooling systems.
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COOLING CHALLENGE
PAO-2 is a strong base fluid for single-phase immersion cooling. Good dielectric behaviour, low viscosity, well understood by the industry. It carries one weakness that matters in a data center: a flash point at the lower end of what fire safety standards accept. In a hall full of energised hardware, which is not a detail.
The design objective for the nano-oil was specific. Raise the flash point of PAO-2 without giving up anything the base fluid already does well. Nanoparticle additives move more than one property at a time, so the question was whether a formulation built for fire safety would still hold its dielectric strength, keep its thermal performance, and leave hardware materials alone.
A datasheet does not answer that for an operator. Submer’s Fluid Validation Service does. It is an independent qualification framework, built on OCP immersion requirements and international test standards, that decides whether a fluid is fit to enter a data center at all.
Industry
Data Centers / Immersion
Product
Synano PAO-Nano (PAO2 nano-oil)
Location
Barcelona, Spain
Year
2025/2026
Intel’s LGA7529 test vehicle
targeted and forced flow heatsink
SOLUTION
Synano PAO2-Nano, designated PP0 in Submer’s report, is a single-phase dielectric nano-oil built on a PAO-2 base modified with alumina nanoparticles. Its primary design objective, recorded at the start of the programme, was a higher flash point than base PAO-2. Secondary objectives were more efficient heat removal and a higher dielectric breakdown voltage.
Submer ran the fluid through the full qualification programme between 15 December 2025 and 6 February 2026, every stage against a published standard. Breakdown voltage was measured per IEC 60156 with VDE electrodes at a 2.5 mm gap, averaged over six measurements. Dissipation factor, volume resistivity and dielectric constant followed IEC 60247 at 90 °C. Closed cup flash point followed the Pensky-Martens method, ASTM D93, averaged over three runs. Thermal conductivity followed ASTM D7896, specific heat capacity ASTM E1269, acidity IEC 62021.
Material compatibility followed the OCP Material Compatibility in Immersion method. Sixteen samples covering structural plastics, seals, cable jackets and adhesives were immersed for 336 hours at 80 °C, with weight, diameter, thickness and hardness measured before and after. The fluid was re-tested after every exposure, so anything picked up from a material would show in the fluid data.
Thermal performance was assessed at system level on an Intel LGA7529 thermal test vehicle at 500 W and 650 W, against its own PAO-2 base oil, across natural convection immersion, forced convection, and targeted flow cold plate at 1 and 2 L/min. The mechanical stack stayed undisturbed between fluids, so any difference could only come from the fluid.
RESULTS
The fluid passed every acceptance criterion in the programme, with margin on all of them.
- The primary objective was met. Closed cup flash point measured 164.8 °C across three runs, against the 150 °C minimum set by OCP immersion requirements and echoed in IEC 62368-1 and NFPA 75. Submer placed the value at the top of the range expected from PAO-2 fluids.
- Dielectric performance cleared every threshold with room to spare. Breakdown voltage averaged 71.4 kV over six measurements, more than double the 30 kV pass threshold and clear of the 40 kV Submer treats as ideal. Volume resistivity measured 525 GΩ·m against a 2.00 GΩ·m minimum, dissipation factor 0.0053 against a 0.05 limit, and dielectric constant 2.06 against a 2.30 ceiling.
- Material compatibility matched or beat expectations. Fourteen of the fifteen material groups performed at or above their predicted result after 336 hours at 80 °C, with PVC better than predicted. Every structural plastic and adhesive passed, along with PTFE, PUR and PVC cable jackets and FKM seals. EPDM, polyolefin and silicone swelled past the limits, which is how those three behave in any PAO-2 based fluid and why immersion tanks and IT hardware already exclude them.
- The fluid itself came through unchanged. Breakdown voltage stayed above the 20 kV acceptance limit after every one of the sixteen exposures, and colour and acidity passed across the board. Fresh fluid acidity measured 0.006 mg KOH/g against a 0.01 ideal.
- Thermal performance held level with the base oil. Across natural convection, forced convection and targeted flow cold plate, at 500 W and 650 W, thermal resistance tracked the PAO-2 base in every configuration. In the immersion cold-plate (targeted flow) configuration, at higher flow rates (2 L/min), a small reduction in thermal resistance was observed (−1.8% at 500 W and −2.0% at 650 W). The PP0 formulation achieves higher flash point with equivalent or slightly enhanced heat removal potential.
Submer validation summary, all ten acceptance criteria met
Predicted against measured material compatibility, 16 samples
Fluid breakdown voltage after each material exposure, against the 20 kV limit
TECHNICAL AND PERFORMANCE IMPLICATIONS
- Closed cup flash point of 164.8 °C, against the 150 °C OCP immersion minimum
- Breakdown voltage of 71.4 kV, more than double the 30 kV pass threshold (IEC 60156)
- Volume resistivity of 525 GΩ·m, against a 2.00 GΩ·m minimum
- Dielectric dissipation factor of 0.0053, an order of magnitude below the 0.05 limit
- Dielectric constant of 2.06, inside the band expected of hydrocarbon immersion fluids
- Thermal conductivity of 0.135 and 0.133 W/m·K at 25 °C and 40 °C, in line with PAO-2
- 16 materials tested to the OCP immersion method for 336 hours at 80 °C, with 14 of 15 groups at or above their expected result
- Fluid breakdown voltage above the 20 kV limit after every material exposure
- Acidity of 0.006 mg KOH/g, inside the ideal band for new dielectric fluids
- Thermal resistance equivalent or slightly better than base PAO-2
- Drop-in formulation with no hardware changes and no system modifications
CONCLUSION
The Submer programme answered the question the formulation was built to answer. Synano PAO2-Nano delivers a closed cup flash point of 164.8 °C, clear of the 150 °C threshold that OCP, IEC 62368-1 and NFPA 75 converge on, and it gives up nothing the base fluid already did well.
For a data center operator the reading is short. The fire safety margin goes up. The electrical safety margin goes up. The thermal design does not change. Existing PAO-2 material guidance still applies, because the three materials that swelled are the same three any PAO-2 system already designs around. No new exclusion list, and no change to tank, pump or hardware specification.
This was the qualification stage of the Submer Fluid Validation Service, and the fluid cleared it. Synano PAO-Nano is validated for use in immersion cooling systems. Extended testing in a Submer SmartPod is the stage that follows.
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