Description
MARLOTHERM® N is an economical synthetic organic heat transfer fluid based on long-chain alkylbenzene derivatives (C14-30 alkyl benzenes), engineered as a cost-effective alternative to mineral oils in liquid-phase, non-pressurized, forced-circulation systems. This synthetic hydrocarbon blend delivers exceptional thermal stability and oxidation resistance at a fraction of the cost of premium synthetic fluids, making it ideal for medium-temperature applications where budget considerations are important. The recommended operating range is 150°C to 300°C (302°F to 572°F), with favorable low-temperature viscosity characteristics permitting cold startup down to -10°C (14°F) using standard centrifugal pumps without heat tracing. Unlike many high-temperature synthetics, MARLOTHERM® N demonstrates remarkable stability when exposed to air—a significant advantage for processing equipment where complete atmospheric isolation is not achievable due to system design constraints. When operated within recommended parameters, the fluid produces no viscous deposits or system-fouling residues, ensuring long-term heat exchanger efficiency.
- Cost-Effective Synthetic Alternative: Delivers synthetic fluid performance at an economical price point, replacing mineral oils in medium-temperature applications with superior thermal stability.
- Exceptional Air Stability: Resists oxidative degradation when exposure to air cannot be completely prevented—ideal for calenders, processing machines, and equipment with inherent atmospheric contact.
- Clean Operation: Forms no highly viscous or solid deposits; no heat exchanger surface coatings or circuit clogging observed when operated within recommended parameters.
- Easy Cold Startup: Pumpable at temperatures as low as -10°C (14°F) with standard centrifugal pumps, enabling reliable startup under unfavorable climatic conditions without heat tracing.
Applications
Processing Machine Temperature Control · Calender Heating · Plastics & Rubber Processing · Textile Manufacturing · Laminating Equipment · Die Temperature Control · Roll Heating · Paper Processing · Wood Processing · Printing Equipment · Packaging Machinery · Extrusion Equipment · Non-Pressurized Heating Systems · General Industrial Process Heating · Equipment with Atmospheric Exposure
Benefits
Economical Alternative to Mineral Oils · Superior Oxidation Stability · No System-Fouling Deposits · Cold Weather Startup Capability · Non-Pressurized Operation · Non-Corrosive to Standard Metals · Compatible with Fluoroelastomer Seals · Long Service Life with Proper Maintenance
Product Availability
5 Gal (20 L) · 55 Gal Drum (200 L) · Bulk (Totes / Tankers)
Product Data
| Property | Value |
| Appearance @ 20°C | Liquid, Clear (Yellow) |
| Composition | Benzene, C14-30-alkyl derivatives |
| CAS Number | 68855-24-3 |
| Density @ 20°C | 0.850–0.900 g/ml (7.09–7.51 lb/gal) |
| Kinematic Viscosity @ 20°C | 28–60 cSt |
| Kinematic Viscosity @ 40°C | 14 cSt |
| Kinematic Viscosity @ 100°C | 3.0 cSt |
| Kinematic Viscosity @ 200°C | 0.87 cSt |
| Recommended Operating Range | 150°C–300°C (302°F–572°F) |
| Max Bulk (Heater Outlet) Temperature | 300°C (572°F) |
| Max Film Temperature | 340°C (644°F) |
| Boiling Range @ 1013 mbar | 330–400°C (626–752°F) |
| Pour Point | ~-60°C (-76°F) |
| Pumpability Limit | -10°C (14°F) |
| Flash Point (EN 22719) | ~180°C (356°F) |
| Autoignition Temperature (DIN 51794) | ~330°C (626°F) |
| Specific Heat @ 200°C | 2.62 kJ/kg·K |
| Thermal Conductivity @ 200°C | 0.121 W/m·K |
| Vapor Pressure @ 200°C | 7 mbar (0.10 psi) |
| Vapor Pressure @ 300°C | 390 mbar (5.66 psi) |
| Chlorine Content | <10 ppm |
| Acid Number | ≤0.02 mg KOH/g |
| Water Solubility | Negligible (0.1 g/L) |
| Decomposition Temperature | ~330°C (626°F) |
Note: MARLOTHERM® N circuits operate optimally with low inert gas blanketing (nitrogen recommended) at approximately 50–100 mbar back pressure on the expansion vessel, even at the upper end of the operating range. While the fluid demonstrates good air stability compared to other synthetics, inert gas protection extends service life and minimizes oxidation effects. At high operating temperatures, thermal decomposition produces low-boiling and high-boiling secondary products in tolerable amounts; low boilers should be removed via the expansion vessel either during operation or during maintenance shutdowns. The fluid charge should be replaced when high-boiler concentration approaches 15% by mass. Construction and operation should comply with DIN 4754 recommendations for organic heat transfer installations. MARLOTHERM® N is non-corrosive to standard plant construction metals; avoid cadmium and zinc as these metals catalyze thermal decomposition of organic compounds. Compatible with graphite, PTFE, and fluoroelastomer seals (quality grade It-0 or equivalent); rubber-elastic materials and conventional thermoplastics (PVC, polyethylene) are not compatible. Annual fluid analysis is recommended to monitor fluid condition and ensure continued trouble-free operation. When molten, the product can cause serious burns—appropriate PPE should be worn when handling hot fluid.
