Marco G. Fernandez

Design and testing of a new smoke concentration meter

The design of a new smoke concentration meter based on light-extinction measurements with a He-Ne laser is described. The measurement allows the determination of the mass-generation rate of smoke and smoke yield during a 5re test with little more time or labour than is required for performing heat-release-rate and mass-loss-rate measurements. The new smoke concentration meter was motivated by the 5nding from several studies of a nearly universal value of the speci5c extinction coe7cient of post-6ame smoke produced by over ventilated 5res. Key design features include the use of a stabilized laser, purge 6ow to eliminate smoke deposition on the optics, U channel construction to minimize the e4ect of heating on the optical alignment and beam correction optics. The facility was fabricated almost entirely from commercially available components to allow this design to be easily reproduced by5re research and testing laboratories. The smoke concentration meter was able to measure a smoke yield as small as 0.005 for a propane 5re to as large as 0.10 for a toluene pool 5re. A detailed uncertainty assessment was made. The result for a 50 cm diameter heptane pool 5re agrees well with previous smoke yield measurements made for the same fuel and pool diameter based on 5lter collection and weighing. Copyright ( 2000 John Wiley & Sons Ltd.

Accurate size measurement of monosize calibration spheres by differential mobility analysis

A differential mobility analyzer was used to measure the mean particle size of three monosize suspensions of polystyrene spheres in water. Key features of the experiment to minimize the uncertainty in the results include developing a recirculating flow to ensure equal flows into and out of the classifier, an accurate divider circuit for calibrating the electrode voltage, and use of the 100.7 nm NIST SRM™ for calibrating the flow of the classifier. The measured average sizes and expanded uncertainties with a coverage factor of 2 are 92.4 nm±1.1 nm, 126.9 nm±1.4 nm, and 217.7 nm±3.4 nm. These calibration sizes were characterized by NIST to improve the calibration of scanning surface inspection systems.

Performance of metal and polymeric O-ring seals during beyond-design-basis thermal conditions

This paper summarizes the small scale thermal exposure test results of the performance of metallic and polymeric O-ring seals typically used in radioactive material transportation packages. Five different O-ring materials were evaluated: Inconel/silver, ethylene-propylene diene monomer (EPDM), polytetrafluoroethylene (PTFE), silicone, butyl, and Viton. The overall objective of this study is to provide test data and insights to the performance of these Oring seals when exposed to beyond-design-basis temperature conditions due to a severe fire. Tests were conducted using a small-scale stainless steel pressure vessel pressurized with helium to 2 bar or 5 bar at room temperature. The vessel was then heated in an electric furnace to temperatures up to 900 °C for a pre-determined period (typically 8 h to 9 h). The pressure drop technique was used to determine if leakage occurred during thermal exposure. Out of a total of 46 tests performed, leakage (loss of vessel pressure) was detected in 13 tests.