A traditional sweating guarded hotplate, also known as a “skin model”, is designed to produce accurate, repeatable measurements of the thermal resistance (Rct) and vapor permeability (Ret) of textiles when tested under steady-state conditions.
Traditional hotplates run into problems when used to test the performance of textiles in conditions that are NOT steady-state.
Thermetrics new Dynamic Hotplate System (DHS) is an exciting evolution in hotplate technology that – in addition to steady-state testing – allows for measurement of Rct and Ret in situations of positive or negative heat flux, and with far greater accuracy in dynamic environments.
The innovative sensor technology used in our Dynamic Hotplate System generates instantaneous surface heat-flux measurements, and as a result the new DHS hotplate is capable of measuring heat loss and heat gain (in Watts/m²), which is necessary for tests of heated fabrics and pads or for textile testing under sustained solar loads and elevated ambient temperatures (up to 50°C)!
The new DHS system can also be used to calculate the mass of a Phase Change Material (PCM) contained in a textile, and it is sensitive enough to identify the melt point and change in thermal conductivity for the solid and liquid phases of PCM textiles. In addition, when PCM’s are used in a composite fabric the DHS can detect where PCM layers will have the greatest impact on cooling and warming, and the DHS system can also measure both the magnitude and duration of a PCM’s “cool to touch” or “warm to touch” sensory effect.
Thermetrics Dynamic Hotplate System features an integrated sweating system with precision microprocessor pump technology. Sweat is preheated within the plate and delivered to the surface through a uniform array of small pores. When combined with our integrated chamber option, the DHS hotplate utilizes the chamber’s water supply, thus eliminating the need for a separate fluid reservoir.
The new DHS hotplate is an excellent physiological simulator and can be constructed with a smaller test zone for customers who may have problems generating prototype swatches in the size used by traditional hotplates.
The DHS-8.2 provides accurate, fully automated testing that is in compliance with ASTM F1868. Due to how the DHS plate is constructed, the system is not compliant with ISO 11092 or ISO 13029. However, selecting the Thermetrics integrated chamber option makes it possible for the system to be equipped with interchangeable “dynamic” DHS-8.2 and “traditional” SGHP-8.2 test plates, thus providing full compliance with ISO 11092, ISO 13029, and ASTM F1868.