Thermal Systems

Closed-Loop Thermal Fluids

Closed-loop thermal oil systems require a heat transfer fluid matched to the maximum operating temperature, heater film temperature and service life requirements of the specific installation. NEXT Lubricants supplies mineral and synthetic thermal fluids for closed-loop heat transfer systems across industrial process heating, solar thermal, waste heat recovery and marine heating applications.

Knowledge

Fluid Selection Considerations for Closed-Loop Thermal Systems

Thermal fluid selection for a closed-loop system is primarily determined by the maximum bulk temperature and heater film temperature of the system — fluid type, operating temperature ceiling and service life are closely linked. Mineral-based fluids cover the majority of industrial applications up to around 300°C. Synthetic fluids extend the operating range for high-temperature duties and offer longer service intervals in demanding applications.

Maximum Operating Temperature

The fluid must be rated for the maximum bulk fluid temperature and heater film temperature of the system — operating above the fluid's recommended temperature limits accelerates thermal cracking and deposit formation, reducing fluid life and increasing the risk of system fouling.

Fluid Condition & Service Life

Thermal fluids degrade gradually through thermal cracking and oxidation during service — regular fluid sampling and acid number, viscosity and flash point analysis are standard practice to determine when fluid maintenance or replacement is required before system performance is affected.

Fire Point & Safety Margins

The fluid's flash and fire point relative to the maximum system operating temperature determines the safety margin of the installation — a fluid operating close to its flash point creates a fire risk in the event of a leak, making fluid selection an important element of system safety assessment.

products

Closed Loop Thermal Fluids

The following thermal fluids are available for closed-loop heat transfer system applications across high-temperature process heating, solar thermal energy systems, waste heat recovery and marine and offshore heating. Final selection depends on maximum system operating temperature, heater film temperature, required service life and system design. If you need assistance selecting the right product, use the recommendation form below or contact our technical team directly.

NEXTHERM 332

Heat Transfer Fluid

Base Oil: Mineral

Max. Bulk Temp:  332°C

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NEXTHERM FG

Food Grade Heat Transfer Fluid

Base Oil: Mineral

Max. Bulk Temp: 327°C

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NEXTHERM HF

High Flash Heat Transfer Fluid

Base Oil: PAO

Max. Bulk Temp: 340°C

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NexthermClean+

Fast-acting thermal oil system cleaner for mineral oil-based thermal systems

Treat Rate: Mineral

ISO Range: 5-10%

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Recommendation

Need Help Selecting a Closed Loop Thermal Fluid?

NEXT Lubricants provides technical fluid recommendations for closed-loop thermal oil systems across industrial process heating, solar thermal, waste heat recovery and marine heating applications.