ASTM E511 is a standard test method for measuring radiative heat flux with a copper-constantan circular foil heat-flux transducer whose sensing element is a thin circular metal foil. Gardon Gauges are a common name for these sensors. The values are considered a standard when expressed in SI units.
ASTM E511 Standard Test Method for Measuring Heat Flux Using a Copper-Constantan Circular Foil, Heat-Flux Transducer
What is ASTM E511?
What is the Scope of ASTM E511?
This test method measures radiative or convective heat flux (or both) using a specific type of sensor. The sensor detects heat fluxes from mixed radiative-convective or purely convective sources; uncertainty increases as the convective portion of the overall heat flux increases. This standard does not address all safety concerns associated with its use, leaving it to the user to establish correct safety practices.
ASTM E511 Testing Procedure and Requirements
Most of the heat energy absorbed at the surface of the circular foil is routed radially to the heat sink when the sensing element is exposed to a heat source. Under steady-state circumstances, a parabolic temperature profile was created between the foil’s center and edge. The thermoelectric potential was created by the temperature differential between the center and the perimeter, and it varied in response to the absorbed heat flux. In an application where the copper heat-sink would reach 235°C (450°F) without cooling, a water-cooled transducer should be used.
ASTM E511 Analysis Results and Interpretation
The radiant heat flux is calculated using the equation:
q’ = E/K
q’ = absorbed heat flux
E= thermoelectric potential
K = sensitivity constant
Updated on August 29, 2026
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