QFS-40 and UVB-313EL lamps are both used in QUV accelerated weathering testers to provide fluorescent UV light that includes a significant UVB component for faster testing. The diagram below shows that both have similarly-shaped spectral power distributions. How do these lamps differ, and which one is best for use in your QUV?
The QFS-40 lamp was developed to meet the specifications of SAE J2020, which, when written, had a hardware-specific requirement to use this lamp. That hardware-specific requirement has been removed in SAE J2020 and in most standards that are based on SAE J2020.
UVB-313EL lamps were developed later, and operate with the QUV’s SOLAR EYE irradiance control system to provide a more consistent and repeatable level of irradiance than using QFS-40 lamps in a QUV/basic, due to lamp aging, maintenance, and environmental conditions. UVB-313EL lamps are significantly less expensive than QFS40 lamps because far greater volumes of UBV-313EL are manufactured.
If your QUV has SOLAR EYE irradiance control, you should use UVB-313EL lamps and set the irradiance to 0.48 W/m2at 310 nm for SAE J2020 and standards based on it, even if those standards have not been updated to include the UVB-313 lamp. This is the most cost-effective and best-performing option when irradiance control is available.
If your QUV does not have irradiance control (QUV/basic or old style models), you should continue to use QFS-40 lamps to maintain comparable irradiance levels to what is intended by a test standard or historical practice. UVB‑313EL lamps used in QUV testers without irradiance control will generate irradiance that is significantly higher than QFS-40 lamps in the same tester.
Q-Lab Corporation is a global provider of material durability testing products. We design and manufacture Q-PANEL standard test substrates as well as weathering, light stability, and corrosion testers. Q-Lab also offers A2LA accredited contract test services, including accelerated laboratory testing. Our weathering products and services are used by materials scientists, research and development engineering, and quality control personnel in numerous industries.