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The meaning of Sweating Guarded Hotplate Testing

2020/09/18

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The sweating guarded hotplate (often referred to as the 'skin model') is a device for measuring the Thermal resistance or water vapour resistance of a material or composite.
 
The test is designed to simulate the transfer processes of heat and moisture through materials next to the human skin and to measure the rate of transfer of heat or moisture in such processes. It is, therefore, particularly relevant for assessing the ability of clothing and footwear materials to transmit moisture or heat, primarily under steady-state ambient conditions.
 
Why We Need the Thermal Resistance Test?
When people wearing clothes in cold or hot climates, the temperature of clothing, especially close-fitting, varies with the temperature of the skin. People should choose suitable clothes to ensure comfort, or at least in adverse weather conditions to protect the human body. The heat transfer property of fabric can ensure the comfort of clothing, for example, the clothing with high thermal resistance has a better function of preventing cold, while the clothes with low thermal resistance can give a cool feeling. Therefore, testing the thermal resistance of fabrics has an important reference for improving people’s clothing comfort.
 
Thermal Resistance Test Principle
The sweating guarded hot plate instrument produced by our company adopts the constant temperature method. Place the sample to be tested on an electric hot plate which has good thermal insulation at all the other surfaces. Transfer heat to an electric heating plate so that it reaches constant temperature state, and test the heat needed to maintain the constant temperature of the electric heating plate. This method has been adopted by ASTM as the standard number ASTM D1518.
 
Sweating Guarded Hot Plate Test Method
Assemble the instrument, install SGHP software according to instructions, connect with thermal resistance instrument through network signal, and prepare for the test.
The RCT0 test is used to express the basic parameter of a machine. The value of Rct0 will be used to calculate the final RCT value of a sample. Rct0 test should be done when the machine stopped for a long time or the environment changed great.
Cut the sample as 50 cm x 50 cm, and pretreat it according to the standard requirements. Place the treated sample on the surface of the test area. If the thickness of the sample is more than 1 mm, then adjust the height of the wind speed sensor so that the height between the sample and the sensor is about 15 mm. According to the standard requirements to set the temp and humidity and then start the test until the testing environment is stable. Record the test results and calculate the final RCT values of the sample.
 
Daily Maintenance
1 Keep the machine clean: Clean the surface of the test plate and the dust of the air of exhaust grid by using the towel.
2 If the Ret test is finished and another Ret test will be run in next day, then open the safety cover and open the door of the conditioning chamber, the water will be evaporated from inside of the machine, and prolong the service life of the machine.
3 If the conditioning chamber will not be used for a long time, please drain off the water of the conditioning chamber.
 

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