Immersion Heaters Provide High-Temperature Heating Flexibility

Chromalox catalog tmo 109 3

The Challenge
The installed system for heating reactors and stills with hot tempering oils was limited in temperature range and could be troublesome. A growing diversity of products required a greater degree of flexibility in temperature range than the hot-oil system could provide. 

The company turned to other heat transfer mediae, but had no success. Heating with a central system for these new mediae was impractical because of the widely different temperature requirements on the various processing vessels. The physical characteristics of the mediae themselves required heat sources of varying temperatures.

The Solution
Because of the wide range of heating requirements, individual heat sources were chosen. On one 350-gallon vacuum still 18 KW of heating capacity now provides temperatures of 290°C. Chromalox Type TMO Immersion Heaters operate in the bottom of the vented vessel jacket which contains the heat transfer medium. Using 30 KW, a 450 gallon sealed jacket reactor can obtain temperatures up to 325°C., using Dowtherm-A.

In some cases, particularly where vessels were equipped with steam coil or for glass lined equipment, it was not practical to insert heaters directly into the vessel or jacket. In these cases, the heat transfer medium was heated adjacent to the vessel and
circulated by means of a sump-type centrifugal pump.


  • Versatility of heating capacity needed.
  • Close control of temperature in each vessel.
  • Economical to install, eliminates central heating system.
  • Faster heat up.
  • Immersion heaters are standard and immediately available from stock.
  • Low operating cost.