Both the QFS-40 and UVB-313EL lamps are used in the QUV accelerated weathering Tester to provide a fluorescent UV lamp that contains the important UVB component for faster testing. The figure below shows the spectral power distribution of both with similar shapes. How are these lights different, and which one is right for your QUV?
The QFS-40 lamp was developed to comply with the specifications of SAE J2020, which was written with hardware-specific requirements for the use of this lamp. Hardware-specific requirements have been removed in SAE J2020 and most SAE J2020-based standards.
The UVB-313EL ultraviolet lamp was developed later to be used with QUV's SOLAR EYE irradiance control system, due to lamp aging, maintenance and environmental conditions, compared to using QFS-40 lamps in QUV/basic, it Provides more consistent and repeatable irradiance. UVB-313EL lamps are much cheaper than QFS40 lamps because the UBV-313EL is manufactured in a much larger volume.
If your QUV has SOLAR EYE irradiance control, you should use a UVB-313EL lamp and set the irradiance at 310nm for SAE J2020 and its standard illuminance based on that standard, even if those standards are not yet Updated to include UVB-313 tubes. This is the cost-effective and best-performing option when irradiation control is available.
If your QUV does not have irradiance control (QUV/basic or older models), you should continue to use QFS-40 lamps to maintain levels of irradiance comparable to those expected by testing standards or historical practice. The UVB‑313EL lamp used in the QUV Tester without irradiance control produced significantly higher irradiance than the QFS-40 lamp in the same Tester.
