Improving Measurement Uncertainty in the Vertical Tray Test (UL 1685, UL2556, IEEE 1202 / FT4)

摘要

In many countries, the Vertical-Tray Fire-Propagation and Smoke-Release Test for Electrical and Optical-Fiber Cables, (UL 1685, UL2556, IEEE 1202, FT4) is an important fire test used by to assess the flammability and smoke generation characteristics of wire and cable products. This paper demonstrates how various tools and methodologies can be used to quantify, improve, and control measurement uncertainty in fire tests, such as the UL 1685 tray test. Standard Reference Materials (SRM's), which can be difficult to identify, assess, and use in practice, are desperately needed to calibrate fire test instruments and qualify operators. Seemingly small changes in test conditions can have a dramatic effect on test results; however operators have limited tools and methods to identify these changes and implement improvements. This paper outlines a method that was used to develop useful calibration tests using common and readily available materials that can be deployed by test laboratories. These calibration tests have the added benefit of isolating specific subsystems for ease of troubleshooting. The data from calibration testing provides insight for the improvement and control of this test. In addition Statistical Process Control (SPC) has been proposed to monitor and improve performance on an ongoing basis. The improvements discussed were achieved by using a widely known Lean/Sigma principle the DMAIC method. Benefits derived from the DMAIC method include: (ⅰ) improved calibration methods and tools; (ⅱ) an improved understanding and control of the sources of variation; and (ⅲ) the development of process control charts to monitor tray test performance.