1. Does the TPS-EFF comply with ASTM 7984-16?
2. How does thickness relate to thermal effusivity?
The required probing depth depends on the diffusivity of the material but is generally below 1cm for materials covered by the standard.
3. How is the TPS-EFF calibrated?
The TPS-EFF is calibrated by applying a model of 1D heat transfer with a given sensor heat capacity and backing insulation effusivity to obtain sample effusivity.
Performing tests on known materials and deriving a calibration curve to correct the raw effusivity reading.
4. Does the TPS-EFF have a guard ring?
No, the TPS-EFF does not require a guard ring. With the TPS-EFF’s larger diameter sensor (30 mm), a guard ring is not required to keep the measurement one-dimensional. The increased area and short test time ensure the heat penetration is one-dimensional for the thermal effusivity covered in standard.
5. Why does the TPS-EFF also measure 10 seconds?
Alongside 2 second tests, 10 second tests are supported as they allow for greater penetration depth, which allows for expanded measurements of contact – touch time to characterize a materials feeling of coolness or warmth. This additional information can be used to alter how a material feels over longer touch times, especially useful for layered textiles and fabrics.
6. What is thermal effusivity?
Thermal effusivity is a special quantity relating the thermal conductivity, heat capacity and density of a material. This relation determines heat transfer across material interfaces. Thermal effusivity can be used to measure how a material feels, in terms of coolness or warmth. It is important to understand, as the thermal conductivity included in the quantity is not only heat transfer through conduction, thermal effusivity should never be used to measure or calculate thermal conductivity due to possibility of significant error.
7. Does the TPS-EFF measure within 1 to 3 seconds? Does it measure longer?
The TPS-EFF can perform 2 second and 10 second tests.
8. How does the TPS-EFF ensure one dimensional heat flow?
One dimensional heat flow is ensured by using a sensor with a large surface area, limiting the test time to 2-10s, and restricting test materials to those covered by the ASTM standard.
9. Is the TPS-EFF calibrated?
Yes, the TPS-EFF is calibrated. This is necessary due to the construction of the sensor.
10. Does the TPS-EFF measure within 5% of known materials?
Measurements made with the TPS-EFF fall within 5% of known materials.