Choosing the correct sheath material and watt density for an application requires an understanding of the relationship between the sheath material, the watt density, and the solution being heated. The following recommendations are based on information compiled over many years of actual use under normal conditions.
These Recommendations can, however, be upset by unusual factors which can effect both the heater life and the media being heated. It is to your advantage to check with both the supplier of the solution and the supplier of the heater in question before using. We cannot guarantee heaters against premature failure due to corrosive action over which we have no control, so please check before having heaters installed.
Suggested Watt Density Ratings
Note: These watt densities may be adjusted when heat taken-away or flow velocity rates are increased or when operating temperatures are altered.
Because it is not possible to anticipate all conditions under which this information and our products may be used, Therm Coil Mfg. Co. cannot be responsible for any electric immersion heater failure that is attributed to corrosion.
| Materials Being Heated |
Max. |
Max. Watts Per Square Inch |
| Acid, Solution or Electro –Plating Tanks | 180°F | 40 W/in² |
| Alkali & Oaklite Cleaning Solution | 212°F | 40W/in² |
| Asphalt, Tar, Heavy Compounds, etc | 200°F 300°F 400°F 500°F |
10 W/in² 8 W/in² 7 W/in² 6 W/in² |
| Bunker C Fuel Oil | 160°F | 10-16 W/in² |
| Caustic Soda 2% 10% 75% |
210°F 210°F 180°F |
45 W/in² 25 W/in² 25 W/in² |
| Downtherm A liquid phase vapor phase |
750°F 750°F |
22 W/in² 10 W/in² |
| Downtherm E | 400°F | 12 W/in² |
| Ehtylene Glycol | 300°F | 30-35 W/in² |
| Freon | 300°F | 3 W/in² |
| Fuel Oil Pre-heating | 180°F | 9-16 W/in² |
| Gasoline, Kerosene | 300°F | 3-5 W/in² |
| Glue | Heat indirectly using water bath | |
| Lead-Stereotype Pot | 600°F | 35 W/in² on casting |
| Liquid Ammonia Plating Bath | 50°F | 25 W/in² |
| Machine Oil, SAE-30 | 250°F | 18-20 W/in² |
| Metal Melting Pot | 500-900°F | 20-27 W/in² |
| Mineral Oil | 200°F 400°F |
20-26 W/in² 16-20 W/in² |
| Molasses | 100°F | 4-5 W/in² |
| Molten Salt Bath | 800°F-950°F | 25-30 W/in² |
| Molten Tin | 600°F | 20 W/in² |
| Oil Draw Bath | 600°F 400°F |
20 W/in² 24 W/in² |
| Paraffin or Wax | 150°F | 16-25 W/in² |
| Sodium Cyanide | 140°F | 40 W/in² |
| Steel Tubing Cast into Aluminum | 500°F-750°F | 50 W/in² |
| Steel Tubing Cast into Iron | 750°F-1000°F | 55 W/in² |
| Socony Vacuum Type Transfer Oil | 600°F | 22 W/in² |
| Therminols and Heat Transfer Oils | 500°F 600°F |
22 W/in² 22 W/in² |
| Therminol 66 | 650°F | 22 W/in² |
| Therminol 77 | 700°F 750°F |
22 W/in² 15 W/in² |
| Trichlorenthylene Vapor Degreasing Solutions |
150°F 275°F |
20 W/in² |
| Vegetable Oil (fry kettle) | 440°F | 30-50 W/in² |
| Water (process) | 212°F | 50-60 W/in² |
| Water (washroom) | 140°F | 80-90 W/in² |