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Square Cartridge Heater End Seals

End Seals

Cement Provides protection against some thicker liquids and dust, however it is not waterproof. It is also somewhat brittle and subject to cracking in high impact or high vibration applications. Up to 2600°F
Ceramic A steatite endpiece provides excellent strength and temperature resistance.  However it offers little protection against moisture or other contaminats.
Epoxy Potting Provides a very good seal with excellent mechanical strength. However, it's adherence to Teflon or silicone rubber lead wire is only fair. It is rated up to 265°F and bonds well to Duraflex lead wire.
Epoxylite Potting Provides similar mechanical properties as epoxy potting. Up to 600°F. 
  • RTV Potting, when used in combination with silicone rubber insulated lead wire, provides the best seal of all options.
  • The down side to silicone is that it is limited to 500ºF and while extremely flexible, it is not as strong mechanically as other options.
  • Although the RTV is rated for 500ºF, silicone rubber leads are only rated to 392ºF. An option is to use Duraflex lead wire instead. Duraflex is rated to 1000ºF and has a heavy silicone coating.
  • While Duraflex is not sold as a waterproof wire, it performs very well in wet environments.
  • Another option is to use crimped on leads, then the power pins are sealed where they enter the heater and the type of lead wire does not matter.


  End Seal Type Max Temp Moisture Protection Contamination Mechanical Strength Vibration Resistance Moisture Applications Vibration or Flexing
square heater with cement potting Cement Potting 2600°F Poor Fair Good Poor Poor Poor

Mica End Piece


2500°F Poor Fair Good Fair Poor Good
square heater with epoxylite potting Epoxylite Potting 600°F Fair Very Good  Very Good Excellent Good Excellent
square heater with RTV potting RTV w/ Silicone Rubber Leads 392°F Excellent Excellent Fair Good Excellent Average
square heater with epoxy potting Epoxy Potting 265°F Good Good Excellent Excellent Good Good
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