High Velocity Thermocouple (HVT) Probe

How do you determine the actual flue gas temperatures and gas constituents inside your boiler?

  • 304 & 316 Stainless Steel Construction

  • Type "K" Thermocouple

  • A water-cooled probe used in gas flow streams up to 2,500°F

power plant performance testing

STORM’s High Velocity Thermocouple (HVT) Probe is ideal for measuring flue gas constituents and temperatures inside the furnace. By utilizing a water-cooled jacket, measuring flue gas temperatures up to 2,500oF is possible, where a non-cooled probe would simply melt. Standard HVT Probes are able to be used through an access port as small as 2” diameter. The probes are available in sizes from 4ft to 20ft in 2ft intervals. Each probe is manufactured from 304 and 316 stainless steel to resist corrosion.


A radiation shield protects the thermocouple from radiating heat to the surrounding surfaces so that the thermocouple will measure a true flue gas temperature, not a bulk gas temperature that most laser-based or IR devices provide. This is possible because the aspirator creates a strong suction to pull flue gas directly over the thermocouple at a high velocity; this high velocity negates the radiation effects from the open tip of the radiation shield. While the probe was designed to provide the user with a true flue gas temperature on a point by point basis, STORM feels its’ greatest asset is the probes’ ability to measure excess oxygen. These two variables can provide great insight into challenges you may be facing with slagging, high spray flows, tube metal temperatures and even point to possible factors that have increased corrosion/wastage of your surface areas. CO and NOX levels can also be measured depending on the gas analyzer that is being used with the test probe.

Probe Consists of:

  • “Chicago” Style Hose Couplings
  • Air Aspirator Assembly
  • Thermocouple Radiation Shield
  • Leverage Point with Clamp
  • Type “K” 304 Stainless Sheathed Thermocouple
  • Integrated Sampling Tube

Testing Locations

Probe Overview

Other Required Equipment for Testing:

  • Gas Sample Conditioner
  • Flue Gas Analyzer (e.g. ECOM J2KN)
  • Digital Thermometer
  • Digital Manometer
  • Single strand of flexible tubing with thermocouple (25ft or 50ft length)
  • Adequate lengths of hose for air supply and water supply and drain
  • Leverage bar for longer probes (generally recommended for 16ft length or greater)