MARLOTHERM® SH is a high-performance synthetic, organic heat-transfer medium for use in the liquid phase in closed, forced circulation heat-transfer systems and can be used over the whole working range without being kept under pressure. The boiling range of the product at atmospheric pressure is above the use limit. The heat transfer medium can be used up to a maximum bulk temperature of 350°C. The film temperature should not exceed the limit of 380°C (716°F) either significantly or for a prolonged period.
MARLOTHERM® SH is most suitable for indirect heating of reactors, polymerisation vessels, distillation columns, heat exchangers in process plants and systems for heat recovery.
MARLOTHERM® SH is also suitable for use in heating and cooling systems. The technical characteristics of a MARLOTHERM® SH charge can also be matched to the specific requirements of a system and optimized by mixing with MARLOTHERM® LH.
Heat-transfer plants containing a MARLOTHERM® SH charge can be started up at temperatures down to -5°C (23°F). Steam tracing is generally not necessary. At external temperatures below -5°C, the heat-transfer medium should be protected from excessive cooling during the shut- down phase, or the viscosity of the charge can be lowered by mixing with an appropriate amount of MARLOTHERM® LH. MARLOTHERM® LH can be added to a MARLOTHERM® SH charge without concern, as long as the system is operated at a heater outlet temperature below the boiling point of MARLOTHERM® LH. At operating temperatures above the boiling point of MARLOTHERM® LH, it is necessary to first check whether the heat-transfer plant is approved for operation at the higher pressure.
MARLOTHERM® SH circuits are most efficiently operated using an inert gas back pressure of less than 100 mbar at the expansion vessel. Nitrogen is a suitable inert gas. Inert gas blanketing is the best protection against changes caused by oxidation. Antioxidants are unstable at operating temperatures above 200°C and are ineffective even after short operating times.
MARLOTHERM® SH is thermally stable at very high operating temperatures. The MARLOTHERM® SH charge can be used for several years with proper maintenance reprocessing and/or top up fluids. At very high temperatures, low-boiling and high-boiling decomposition products are formed.