Model HTP


Thermocouple, Sulfur Processing Service

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

The design of the HTP is a result of careful attention to design detail, more than 50 years of experience, and numerous field installations. The thermocouple junction is isolated 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 HTP is built to meet each customer’s specific installation requirements, such as thermocouple type, insertion length, and construction materials. Installation tools are available, and recommended to accurately produce the refractory aperture in the correct size and alignment needed by the refractory thermowell and HTP 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
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  • Accuracy is continuously verified
  • Integral refractory dry out thermocouple reads accurately to 1°F (0.6°C)
  • Worldwide service and parts capability
  • Also used in process incinerators, POX units, and coal gasifiers
  • Special designs to 10,000 PSIG (70 MPa) or 4000°F (2200°C)
  • ATEX version available
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  • 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)
  • 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 Well, Model HFS Flush Gas Station
  • Optional Accessories: Model HRG Refractory Drilling System, Model TEW Thermocouple Extension Leadwire, Model HMB Horizontal Mounting Bars, Model HRS Refractory Stop, Model HRM Casting Mandrel, Refractory diamond drills, Field training, consultation and assistance

Certifications & Approvals

  • Housing:
    Third Party Listed by CSA NRTL/C (USA and Canada) Class I, Groups B, C and D; Class II, Groups E, F and G; Class III; Encl 4X

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

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Additional Information


Thermocouple, Sulfur Processing Service

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