DSET Laboratories, Inc. pioneered accelerated outdoor weathering in the 1960's with its Fresnel-reflecting solar concentration devices - Emma® (Equatorial Mount with Mirrors for Acceleration) and EMMAQUA® (Equatorial Mount with Mirrors for Acceleration with Water).
Economical, proven and continuously improved for even greater accuracy, EMMAQUA is the most widely used outdoor accelerated weathering test method in the world today.
EMMAQUA is unique in that it concentrates natural sunlight via 10 highly reflective, specially coated mirrors onto the specimen target area with an intensity of approximately eight suns. The device tracks the sun and exposes specimens to the full spectrum of sunlight, making it one of the most realistic accelerated tests available. And because EMMAQUA provides an excellent spectral match to sunlight, it correlates well to subtropical conditions, such as Southern Florida, as well as an arid desert environment, such as Arizona.
The test apparatus is a follow-the-sun rack with mirrors positioned as tangents to simulate a parabolic trough.
The target board, located at the focal line of the mirrors, lies under a wind tunnel along which a deflector directs ambient temperature cooling air across the specimens. A fan spray nozzle assembly is employed to spray the specimens with deionized water in accordance with established schedules. Night time spray cycles can be used to keep the specimens moist during the night time hours.
Atlas recommends the exposure of test specimens based on an accumulated dose of ultraviolet radiation measured in MJ/m2. However, test can also be timed on total radiation, Langleys, or real time. The duration can be based on Arizona or Florida radiation equivalents. The UV radiation must be measured as direct beam to avoid errors when evaluating the exposure duration.