L&L Parts

L&L Parts

Mullite Thermocouple Protection Tube, Long, Open, New Type

Mullite Thermocouple Protection Tube - Unit is 7" Long x 1" Diameter with a stepped head for use with all Longer Length Type-K 8 Ga. Thermocouples. NOTE: This is the newer type open end tube which was put into service for new kilns starting in November 2020.

  • NOTE: If you have the old closed-end tubes and you are changing one tube you need to change all of them to the new, open ended type.  If you purchase one, you will receive a full set to change over the entire kiln.


    Mullite Thermocouple Protection Tube - Unit is 5" Long x 1" Diameter with a stepped head for use with All Standard Length Type-K 8 Ga. Thermocouples. NOTE: This is the newer type open end tube which was put in service with new kilns starting in September 2020.

    Why this was changed: 

    When we first started using the closed-end tubes we were able to get a very consistent thickness of the ceramic tube. This produced a known offset that we could program into the controls. The consistency is no longer to our standards and this makes it difficult to know the correct offset until after a kiln is being fired in use. This can cause excessive testing and work on the part of some customers.

    Advantages of the new open tubes: 

    1. Protects the thermocouples from damage while loading the kiln. 

    2. Keeps the oxide dust from the thermocouple tip from getting into the kiln while firing. (Any dust should still be vacuumed when doing the normal cleaning of the kiln). 

    3. Protects thermocouples from excessive radiation error from the nearby hot elements. 

    4. Reduces zone control errors because the tips of all thermocouples are equally exposed to the heat of the kiln. Also, ErrF errors should no longer happen because of the better response of the thermocouple. 

    5. Thermocouple offset of 18 Deg F is no longer required. (We are now setting this to "0" in the factory.) 

    6. Note: It is still possible to change the thermocouple offset to balance heat output in the kiln. 


    1. Replace all tubes at one time. Talk to our office about special discounted pricing if you do this.

    2. Change the thermocouple offset to “0” (Zero) on all two or three zones. 


    1. For a DynaTrol: https://hotkilns.com/change-thermocouple-offset 


    1. Press MENU 

    2. Press 3-Adjustment 

    3. Press 2-TC Offset


    1. See pages 10 and 11 of your One-Touch manual. You can access it here: https://hotkilns.com/sites/default/files/pdf/one-touch-operation-deg-f-2016.pdf

    See this PDF for details.


  • Part Number:
  • Price:
  • Lead Time:
    One to Two Days
  • Return Policy:
    Part is returnable for a 25% restocking charge