Model HTX


Thermocouple, Sulfur Processing Service, ATEX, IECEX

The Delta Controls Model HTX Thermocouple is designed for the primary purpose of reliably protecting a vessel and its refractory lining from excessive temperatures. The HTX provides long-term accuracy and reliability in sulfur processing service.

The design of the HTX is a result of careful attention to design detail, more than 50 years of experience, and numerous field installations. The thermocouple junction is protected from corrosive and invasive gases by using a constant low-flow flush gas circulating across the junction. The flush gas is kept at a pressure higher than the internal reactor pressure to mitigate the migration of process gases through the primary thermowell, body, or seals. Process gases that enter are carried away by the flush gas. The metered flush gas flow has an insignificant effect on the accuracy of the temperature measurement.

The HTX is built to meet each customer’s specific installation requirements such as thermocouple type, insertion length, and construction materials. Installation accessories are available, and recommended to accurately produce the refractory borehole in the correct size and alignment needed by the refractory thermowell and HTX Thermocouple assembly.


  • Worldwide standard for protecting Claus thermal reactors
  • Maintenance free
  • Remains accurate under extreme conditions
  • Protects and extends the useful life of refractory and improves reactor up-time
  • More than 50 years of proven results in hundreds of installations worldwide
  • Keeps working accurately in sulfur service long after other thermocouple designs fail
  • Accuracy is continuously verified


  • Thermocouple Types: B, R, S (others available)
  • Flange Material: Carbon steel or stainless steel
  • Trim, Bolting, Seats: Stainless steel
  • Primary Thermowell:Blended alumina ceramic
  • Process Connection: ANSI 6.0 in Class 150 std (other sizes, types, ratings available)
  • Flush Gas: Nitrogen (11 L/h)
  • Ingress Protection: IP65
  • Working Pressure: 150 psig (10 bar) at vessel skin temperature of 500 °F (260 °C)
  • Working Temperature: 0 °F to +3100 °F (0 °C to +1700 °C)
  • Required Accessories: Model HNP Nozzle Packing Kit Model HRW Refractory Thermowell Model HFS Flush Gas Station
  • Optional Accessories:Model HRG Refractory Drilling System, Model TEW Thermocouple Extension Wire, Model HMB Horizontal Mounting Bar, Model HRS Refractory Stop, Model HRM Casting Mandrel, Field training, consultation and assistance

Certifications & Approvals

  • 70131733 Ex db IIB + H2 T3 Gb Class I Zone 1, AEx db IIB + H2 T3 Gb
  • Sira 18ATEX1044x II 2G, Ex db IIB + H2 T3 Gb Ta = -4 °F to +158 °F (-20 °C to +70 °C)
  • IECEx SIR 18.0012x Ex db IIB + H2 T3 Gb
  • EAC TR CU 012/2011

Required Ordering Information

  • Detailed model number
  • Tag or nameplate detail (if required)
  • Documentation & testing packages (if required)
  • Installation Details
    Nozzle inside diameter
    Shell thickness
    Nozzle inside height
    Refractory thickness
    Nozzle angle from vertical

Additional Information


Thermocouple, Sulfur Processing Service, ATEX, IECEX

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