Surface Probe – Maltec-T ST-31B


  • 0°C ~ 400°C
  • Fast response probe.
  • Ideal for measuring the surface temperature of small electronic parts

Dpstar is a professional thermocouple supplier in Malaysia. We offer a wide range of handheld thermocouple probes to suit a variety of applications. They are perfect for easy handling, quick use temperature measurement. A thermocouple probe consists of thermocouple wire housed inside a metallic tube. The wall of the tube is referred to as the sheath of the probe. Common sheath materials include stainless steel and Inconel. Inconel supports higher temperature ranges than stainless steel, however, stainless steel is often preferred because of its broad chemical compatibility. For very high temperatures, other sheath materials are also available. Thermocouple sensor probes come in various styles unique to different applications. Each style consists of a thermocouple sensing junction protected by a sheath with a termination option.

Maltec-T ST-31B – Designed to measure the temperatures of surfaces. The junction of the surface probe is flat, ensuring that the whole measuring surface remains in complete contact with the surface to be measured. These probes can be equipped with springs that will help the probe maintain constant contact with the surface or a sheath.

How Thermocouple Probe Works?

Thermocouple probes operate on the principle that an electromagnetic force (emf) is generated when heat is applied to the junction of two dissimilar metals (sending junctions). At the other end of the wires, usually, as part of the input instrument, is another junction called the reference junction. The temperature is inferred based on the emf difference between the sensing and the reference junction, which is at a known temperature. Thermocouple probe junction types include exposed junction, ungrounded junction, and grounded junction.

Thermocouple Probe Junction Types

Sheaths with small diameters have faster response times; sheaths with larger diameters have longer life and are better for measuring higher temperatures.

Exposed Junction has the fastest response time, ideal for measuring rapid temperature changes. Clear coating on most models provides a humidity barrier for the thermocouple. Do not use with corrosive fluids or atmospheres.


Ungrounded Junction has a welded junction insulated from the protective sheath and is electrically isolated. Longer response time; use for conductive solutions or where isolation of the measuring circuitry is required.


Grounded Junction has a junction welded to tip of sheath. Wires are completely sealed from contaminants. Good response time.


Probe Sheath/Body Materials

  • Inconel 600 Sheath is ideal for severely corrosive environments and elevated temperatures. Resists progressive oxidation. Maximum operating temperature: 1148°C (2100°F) continuous; 1371°C (2500°F) intermittent.
  • 304 SS Sheath is for general-purpose use, is corrosion-resistant, and good for food service and biological applications. Maximum operating temperature: 898°C (1650°F) continuous; 1398°C (2550°F) intermittent.
  • 316 SS Sheath has higher corrosion resistance than 304 SS. Withstands some strong acids. Maximum operating temperature: 898°C (1650°F) continuous; 1371°C (2500°F) intermittent.
  • SS Sheath with Coating of PTFE or PFA with grounded junction is ideal with corrosive liquids and atmospheres. Longer response time. Temperatures to 260°C (500°F).
  • Polymer Body Probes are available in a variety of polymers including Kapton and PTFE. These provide excellent flexibility and often good chemical resistance. Be sure to consult a chemical compatibility table when selecting a probe for your application.

Types of Thermocouple Probes

Dpstar’s range of hand-held thermocouple probes are designed for: immersion, in a liquid; surface, placed in contact; insertion, into a solid; air or within an airflow.

  • Immersion probes, used in liquids or semi-solids and have a flat or rounded tip.
  • Insertion probes are used to pierce solids and are often used within the food industry and have a pointed spear tip.
  • Contact probes are used to monitor surface temperatures and have a sprung-loaded or bulbous ribbon head.
  • Air probes are used to monitor air temperatures in ducting or flues in ducting or flues and often come with an exposed junction, which aids response time.


Thermocouple sensor probes are used widely across almost any and every commercial and industrial temperature process control application.


Maltec-T ST-31B Surface Probe_DpstarGroup