The QUV allows two approaches to moisture simulation. For most applications, condensing humidity is the best way to simulate outdoor moisture attack. All QUV models allow a programmed condensation cycle. Because certain applications also require water spray to achieve realistic results, some QUV models can produce both condensation and water spray.

Condensation
In many outdoor environments, materials are wet more than 12 hours each day. Research indicates that the main cause of this outdoor wetness is dew, not rain. The QUV simulates this using a unique condensation mechanism. During the condensation cycle, a water reservoir in the bottom of the test chamber is heated to produce vapor. The hot vapor maintains the chamber at 100% relative humidity, at an elevated temperature.

The QUV is designed so that when the test specimens are in place they form the sidewall of the chamber. Thus, the reverse side of the specimens is exposed to ambient room air. This room-air cooling causes the test surface to drop a few degrees below the vapor temperature, assuring that water continually condenses on the specimen surface. The resulting condensate is very stable, pure distilled water.

Water Spray
In some actual service environments, sudden temperature changes can occur when heat builds up over the course of a sunny day, then is rapidly dissipated by a sudden rain shower. The resulting thermal shock is a challenge for many materials. The QUV water spray is useful for introducing thermal shock and/or mechanical erosion.