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8 Series Heat Flux Transducers

Product Details

Our 8 Series Heat Flux Transducers feature a 1/8” diameter Sensing Tip. They can fit into tight locations or may be spaced closely together to measure the heat flux distribution with fine spatial resolution, yet they are large enough to be relatively easy to install and handle. These transducers offer dependable direct measurement of heat transfer rates by a truly miniature transducer in a variety of applications due to careful design, rugged quality construction and a wide variety of mounting configurationsEach transducer is usually designed to provide a self-generated 10 millivolt output at the design heat flux levelContinuous readings from zero to 150% design heat flux are made with infinite resolution. The linear transducer output is directly proportional to the net heat transfer rate absorbed by the sensor. These transducers have been proven in thousands of applications in aerospace flight and model testing, heat transfer research, fire testing, and boiler design. 

8 Series Heat Flux Transducer Features 

  • Miniature Size 
  • Linear Output 
  • Output Proportional to Heat Transfer Rate 
  • Accurate, Rugged, Reliable 
  • Convenient Mounting 
  • Uncooled or Water Cooled 
  • Measure Total Heat Flux 
  • Radiometer Models Measure Radiant Heat Flux 


8 Series Heat Flux Transducer Construction 

  • Accuracy, Ruggedness and Reliability are provided by the thoroughly proven Gardon and Schmidt-Boelter sensors. 
  • Long Transducer Life and Signal Stability are enhanced by the body of OFHC copper. 
  • Signal Integrity is protected using welded connections, maximum practical size lead wire with Teflon, fiberglass or polyimide insulation firmly secured in the transducer body with maximum available strain relief to ensure the greatest possible resistance to rough handling and stray signals. 


Select one of the 8 Series transducers when at least one of the following conditions applies. 

  1. Multiple measurement locations must be spaced close together. 
  1. The mounting is in a location that will not allow a larger transducer body. 
  1. The combination of a small sensing tip and a larger integral heatsink at the back will allow operation of an uncooled transducer over a needed longer test duration. 
  1. The small sensing tip diameter will allow some conformal contouring of the gage surface on installation in a curved surface or may eliminate the necessity of contouring the sensor tip. 

8 Series Heat Flux Transducer Selection of the Water Cooling Option 

The standard 8 Series transducers are designed for a maximum body temperature of 400°F.  The mass of many of the transducer housings is very small so that, except for the shortest test durations, the heat absorbed by the sensor must be removed by conduction to a larger integral heat sink behind the 1/8 inch tip, or by conduction to the structure in which the transducer is mounted, or by water cooling or air cooling the transducer. 


  • Direct Reading Heat Flux Meter Model H-201 is available for direct readout in any heat flux units from any linear heat flux transducer input.  A 0-1 volt recorder out is also provided. 
  • Body or Surface Temperature Thermocouple measurement may be provided by an optional copper constantan 30 AWG solid conductor thermocouple, TIG welded junction, with Teflon, fiberglass, or polyimide insulation. 

Standard Configurations 

The basic transducer may be selected from a number of standard mounting configurations or custom-designed to meet the application requirements.  Many of the configurations may be selected with or without provisions for water cooling of the transducer body. 

8 Series Heat Flux Transducer Specifications 

Standard Ranges Available: 4000, 3000, 2500, 2000, 1500, 1000, 500, 250, 200,100, 50, 30,25,20, 15, 10, 5, 2 Btu/(ft²s). design heat flux level. 

Output Signal:  Most units are designed for 10 millivolts nominal at full range.  The maximum sensitivity for the 8 Series (1/8 inch diameter body) Gardon gage is about 0.3 mV per Btu/(ft²s) and about 4 mV per Btu/(ft²s) for the Schmidt-Boelter thermopile gage. 

Maximum Allowable Operating Body Temperature: 400°F. 

Overrange Capability: to 150% of full range for 2-1000 Btu/(ft²s). ranges, when adequately cooled. MAXIMUM NON-LINEARITY: ±2% of full range. 

Repeatability: ±1/2% 

Expanded Uncertainty Of Calibration: ±3% for ranges to 250 Btu/(ft²s), k=2 for about 95% confidence level. 

Sensor Absorptance: Gardon gages, 92%, nominal, from 0.6 to 15.0 microns.  Thermopiles, 94% to 96%, nominal, from 0.6 to 15.0 microns. 

Spectrum Transmitted By Sapphire Window (when used): 85% nominal from 0.15 to 5.0 microns. Other window materials are optional. 

Lead Wire: When size allows, 24 AWG stranded copper, two conductor, Teflon insulation over each, metallic overbraid, Teflon overall, 36″ long standard, stripped ends.  (The optional thermocouple wire is then 24 AWG Teflon insulated duplex solid conductor.)  Otherwise, usually 28 or 30 AWG Teflon or polyimide insulated duplex or singles, as size allows. (The optional thermocouple wire is then 28 or 30 AWG duplex or singles with Teflon or polyimide insulation.)  The wire used on each model is the sturdiest allowed by the size of the transducer.  Details are contained on each model specification drawing. 

Response Time 

  • 250 to 4000 Btu/(ft²s): less than 50 msec, can be as low as 10 msec. 50 to 200 Btu/(ft²s): less than 100 msec. 
  • 2 to   30 Btu/(ft²s): less than 250 msec, lower as an option. 

Sensor Type 

  • 50 to 4000 Btu/(ft²s): Gardon Gauge 
  • 2 to 30 Btu/(ft²s): Schmidt-Boelter thermopile  

Nominal Impedance 

  • Less than 10 ohms on Gardon Gauges 
  • Less than 100 ohms on Schmidt-Boelter thermopile. 



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