ASTM G155: Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Materials

Test Parameters

The practice includes 14 representative test cycles, each providing different conditions tailored to end-use application and material.

• Light Source
  • All exposure cycles use xenon-arc lamps that are filtered based on the material’s service end-use environment. Optical filters are explicitly defined by the resulting spectral irradiance of xenon lamp light through the glass filter and are classified into three categories:
    • Daylight optical filters are used to simulate outdoor sunlight on earth’s surface and are specified for test cycles 1, 2, 3, 7A, 9, 12, and 13.
    • Window Glass filters simulate sunlight through window glass and can used for cycles 4, 5, 6, 10, and 11.
    • Extended UV filters are more transmissive of UVB wavelengths and provide a harsher spectrum than what is seen on earth’s surface. Cycles 7 & 8 use these filter types and have historically been used by the automotive industry.
  • Light intensity can be controlled by onboard irradiance sensors. Different cycles call for different control points - narrowband 340 nm (1, 2, 3, 4, 7, 7A, 8, 12, 13) or 420 nm (5, 6, 11), or broadband TUV (300-400 nm) (9, 10). Apparatuses without controlled irradiance are allowed by the standard but their market presence is limited. All Q-SUN testers control irradiance with the SOLAR EYE system.
• Temperature
  • Temperature is measured and controlled by an uninsulated black panel temperature sensor in all ASTM G155 test cycles.  Black insulated sensors and white panel sensors are also described in the standard but are not used in any of the exposure cycles. Black panel temperatures range from553 to 89 °C during light steps and are lower during dark steps.
  • Many xenon-arc chambers, including the Q-SUN Xe-2, Xe-3, and Xe-8, include an onboard chamber air temperature sensor (CAT) in addition to the black panel. Cycles 7, 7A, and 8 require CAT control; CAT setpoints are included as recommendations for the others.
• Moisture
  • Water delivery for xenon-arc test chambers is typically accomplished through water spray. Front-surface specimen spray is common for outdoor applications and is used in cycles 1, 2, 3, 5, 9, and 13. Front spray and back spray are used in cycle 7 & 7A.
  • Relative humidity (RH) control is also included in ASTM G155 to influence materials' time of wetness. All cycles except 1 and 2 require RH control. Exposure cycles without water spray (6, 8, & 12) include longer periods of dark and humid environments.
  • Water immersion is also allowed within the standard, but is not overly common and is not included in any test cycle.

You can find in-depth information on how to program ASTM G155 test cycles into your Q-SUN xenon-arc weathering chamber by logging into your  Q-Portal account.