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SDL Atlas

SDL Atlas Sweating Guarded Hotplate Improved

Release Date 11.08.12Subscribe RSS

Although the functional requirements for clothing items are of the most principle concern, especially for performance and safety equipment, the comfort aspects of an item of clothing cannot be ignored. And while comfort can be very subjective, it is generally agreed upon that an item can be consider uncomfortable if it impedes the flow of heat and moisture from the body. Testing the thermal and evaporative resistance of clothing with a Sweating Guarded Hotplate has long been the primary measure of the relative merit of a particular material’s potential comfort.

SDL Atlas for several years has been producing the M259B Sweating Guarded Hot Plate which was initially designed specifically to be fully compliant with the ISO 11092 (also known in Europe as EN31092). The instrument produced results that correlated with the famous Hohenstein Institute Skin Model but at a price level that made it widely accessible to laboratories around the world. 

In response to customer feedback, SDL Atlas recently redesigned their Sweating Guarded Hotplate in order to more closely comply with additional international standards for testing heat and moisture transfer properties. Many laboratories use the SDL Atlas Sweating Guarded Hotplate to perform tests to the requirements of ASTM F1868 , Standard Test Method for Thermal and Evaporative Resistance of Clothing Materials Using a Sweating Hot Plate. This standard has for many years included a reference to ISO 11092 for a description of the construction of the hot plate, but had a more detailed description of the apparatus construction. To avoid any doubt on compliance to this standard, SDL Atlas has revised the controls to be fully in line with the construction and controls detailed in the ASTM standard. Another standard that may be used is ASTM D1518,Standard Test Method for Thermal Resistance of Batting Systems Using a Hot Plate. The SDL Atlas Sweating Guarded Hotplate meets the instrument requirements for that standard’s option 2 when ordered with the optional extended temperature range controls.

The new design now features a three section hotplate composed of a test plate, guard section, and bottom plate. Each plate electrically and independently maintains a constant temperature in the range of human skin temperature (33 to 36°C). The guarded plate has also been widened to 127mm to provide a better lateral heat barrier and ensure that the measured heat flow is flowing vertically through the sample. The new wider guard now has four grooves on each edge, allowing the operator to simply lay the fabric on the plate, drop the sample tie bar in place reducing both the test setup time and potential for user errors when placing the sample.

Other design enhancements that have been made include modifications to the temperature sensor and humidity guard. The new design brings the temperature sensor closer to the porous plate’s open surface, thus improving the ability to measure the real surface temperature of the sample that is touching the plate. The number of sensors also has also been increased. Each section now features three sensors for monitoring the temperature; two are surface mounted on top of the porous plate with a third mounted under the porous plate, for a total of 9 temperature measurement channels working simultaneously. The enhanced humidity guard now features the same sintered bronze porous plate construction that the hotplate has in order to give a more accurate simulation of human skin model when doing evaporation testing. Now both the hot plate and guard plate are immersed in water when doing the evaporation test, which eliminates any lateral transfer to make sure all vaporized air flows through the sample vertically.

The redesign also features a new removable side panel that offers an easier way to access the internal part of the humidifier allowing for easier cleaning and maintenance of the instrument. This improvement reduces the regular maintenance downtime significantly.

“Here at SDL Atlas, we pride ourselves in providing the best possible testing experience for our customers.” said SDL Atlas President, Chuck Lane. “Our engineers are constantly looking for new ways to enhance our existing products to better serve our customers.”

The newly enhanced SDL Atlas Sweating Guarded Hotplate is now available for order. For more information about the instrument, inquiries can be made to any SDL Atlas office or agent.

The SDL Atlas Group of companies offers the largest range of textile testing equipment, supplies, consumables, and services available from a single source. With its own offices in the United States, Hong Kong and China, plus agents in over 100 countries, SDL Atlas is ready to support its customers anywhere in the world. The goal of SDL Atlas is to provide customers with the most complete solution at the best value.

For more information, visit or contact an SDL Atlas solutions expert:

(US) T: +1 803 329 2110; F: +1 803 329 2133; E:

(Hong Kong) T: +852 3443 4888; F: +852 3443 4999; E:

(China) T: +852 3443 4888; F: +852 3443 4999; E:


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