System design analyses and experimental study on sweating guarded hotplates

In order to accurately understand the system principle of sweating guarded hotplates and relative measurement standards for researchers and users,the design features of two typical sweating guarded hotplates of SGHP and M259 B in the world were analyzed. The principles of measurements especial for isothermal and non-isothermal evaporative resistance under relative standards were expounded. The data of thermal resistances and evaporative resistances with isothermal or non-isothermal of 20 pieces of fabrics were measured by SGHP-10. 5. The results showed that the thermal resistance were very similar between two standards with setp difference of air temperature, while the isothermal evaporative resistances were generally higher than that of non-isothermal evaporative resistances by the average17. 7%,which is resulted from hypothesis of the same values of thermal resistance in dry state and moisture absorbed in non stepless method of non-isothermal evaporative resistance measurement. By comparing with measured data of M259 B in literature,the difference of bare plate data is great,deducing a relative big system error exists in that M259 B compared with SGHP-10. 5.