Product Description
MARLOTHERM® SH is a premium synthetic organic heat transfer fluid based on dibenzyl toluene (CAS 26898-17-9), engineered for high-temperature liquid-phase operation in closed, forced-circulation systems. This high-performance fluid operates across its entire working range at atmospheric pressure—no system pressurization required—because its boiling range (385–395°C) lies well above the maximum recommended bulk temperature of 350°C (662°F). The dibenzyl toluene molecular structure delivers exceptional thermal stability at elevated temperatures while maintaining favorable low-temperature characteristics that permit cold startup down to -5°C (23°F) without steam tracing. MARLOTHERM® SH is non-corrosive to standard plant construction materials and compatible with graphite, PTFE, and fluoroelastomer seals. For applications requiring enhanced low-temperature performance or specific viscosity characteristics, MARLOTHERM® SH can be custom-blended with MARLOTHERM® LH to optimize system behavior across the full operating envelope.
- High-Temperature Liquid-Phase Operation: Operates up to 350°C (662°F) bulk temperature with 380°C (716°F) maximum film temperature—all without system pressurization.
- Outstanding Thermal Stability: Dibenzyl toluene chemistry provides exceptional resistance to thermal degradation; properly maintained charges deliver years of reliable service.
- Cold Startup Capability: Pumpable to -5°C (23°F), eliminating heat tracing requirements for most installations and enabling rapid system startup.
- Industry-Leading Flash Point: 200°C (392°F) flash point—among the highest in its class—provides enhanced operational safety at elevated temperatures.
Applications
Chemical Processing
Plastics & Polymer Manufacturing
Reactor Heating
Polymerization Vessels
Distillation Columns
Process Dryers
Heat Exchangers
Heat Recovery Systems
Styrene Production
Pharmaceutical Manufacturing
Industrial Process Equipment
Indirect Heating Systems
Combined Heating & Cooling Systems
Benefits
Non-Pressurized Operation Throughout Working Range
Exceptional High-Temperature Thermal Stability
Cold Startup Without Heat Tracing
High Flash Point for Enhanced Safety
Non-Corrosive to Standard Materials
Compatible with Graphite & PTFE Seals
Blendable with MARLOTHERM® LH
Multi-Year 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 |
| Composition | Dibenzyl Toluene (100%) |
| CAS Number | 26898-17-9 |
| Density @ 20°C | 1.04–1.05 g/ml (8.68–8.76 lb/gal) |
| Kinematic Viscosity @ 20°C | 42–52 cSt |
| Kinematic Viscosity @ 40°C | 16.5 cSt |
| Kinematic Viscosity @ 100°C | 3.1 cSt |
| Pour Point | -34°C (-29°F) |
| Pumpability Limit | -5°C (23°F) |
| Boiling Range @ 1013 mbar | 385–395°C (725–743°F) |
| Flash Point (Pensky-Martens) | ~200°C (392°F) |
| Autoignition Temperature | ~500°C (932°F) |
| Max Bulk Temperature | 350°C (662°F) |
| Max Film Temperature | 380°C (716°F) |
| Specific Heat @ 200°C | 2.22 kJ/kg·K |
| Thermal Conductivity @ 200°C | 0.107 W/m·K |
| Vapor Pressure @ 300°C | 200 mbar (2.90 psi) |
| Vapor Pressure @ 350°C | ~700 mbar (~10 psi) |
| Chlorine Content | <10 ppm |
| Acid Number | 0.02 mg KOH/g |
Note: MARLOTHERM® SH circuits operate most efficiently with inert gas blanketing (nitrogen recommended) at less than 100 mbar back pressure on the expansion vessel. Inert gas protection is the most effective measure against oxidative degradation—antioxidant additives are unstable above 200°C and become ineffective after short operating periods. At operating temperatures above 340°C, continuous removal of low-boiling decomposition products via the expansion vessel is recommended; maintaining the expansion vessel at approximately 150°C assists this process. Decomposition products remain dissolved in the charge and do not form deposits when operated within recommended parameters. For combined heating/cooling applications or enhanced cold-weather performance, MARLOTHERM® LH may be blended with MARLOTHERM® SH, provided the system operates below the boiling point of MARLOTHERM® LH or is approved for the resulting higher vapor pressure. Annual fluid analysis is recommended to monitor fluid condition and ensure continued trouble-free operation. MARLOTHERM® SH is designed in accordance with DIN 4754 standards for organic heat transfer installations. Rubber-elastic seal materials are not compatible—use graphite, PTFE, or fluoroelastomer seals only.