Joseph Z. Su

Multifunctional single-walled carbon nanotube–cellulose composite paper

Single-walled carbon nanotubes (SWCNTs) have been used as fillers to produce electrically conductive composite papers. While conductive composite papers have been made using other fillers, they either suffer from instability or low conductivity. Using simple papermaking techniques, we have made SWCNT–cellulose composite paper which possesses a conductivity of 3 × 10−2 S cm−1 and is comparable to or exceeds other reports of carbon nanotube–cellulose papers made by layer-by-layer assembly. These composite papers are multifunctional, having both improved electrical conductivity and enhanced flame retardant properties over the control paper.

Examination of the Extinguishment Performance of a Water Mist System Using Continuous and Cycling Discharges

We conducted a series of full-scale fire tests of a twin-fluid water mist system in an empty enclosure and in a simulated machinery space. During the tests, two water mist discharge modes, continuous and cycling, were used. We investigated the extinguishment performance of the water mist system using these two discharge modes under various fire scenarios, including different fire sizes, types, and locations, and different ventilation conditions. Test results showed that use of the cycling discharge substantially improved the effectiveness of the water mist system for fire suppression, in comparison to the continuous discharge. The corresponding extinguishing time and water requirement for fire suppression were significantly reduced, and some fires that could not be extinguished with the continuous discharge were extinguished with the cycling discharge. The improvement in fire suppression was attributed to high depletion and dilution rate of oxygen and the recurrent dynamic mixing generated by the cycling water mist discharge in the compartment.

Full-Scale Evaluation of Halon Replacement Agents

Full-scale fire suppression testing of HFC-227ea and HCFC Blend A was conducted in a 121 m3 compartment. HFC-227ea was tested at 7.6 and 8.8%; HCFC Blend A was tested at 8.6, 9.3, 10, 12 and 14% (by volume). Information on discharge characteristics and fire suppression performance of these halon replacement agents was obtained. HFC-227ea extinguished all test fires at the test concentrations. HCFC Blend A extin guished all test fires only at test concentrations of 12% or higher. These two agents produced halogenated acid gases whose quantity depended on the type, concentration and discharge of the agents and the size of the test fires. Language: en

An investigation on fire performance of FRP strengthened R/C Beams

As the use of Fibre-Reinforced Polymer (FRP) materials continues to expand into the structural repair market, concerns over the performance of these materials in fire conditions are now at the forefront of research. While externally bonded FRP sheets have been shown to successfully enhance the flexural and shear capacity of bridges and other structures, their application in interior spaces, where fire is a significant concern, remains questionable in light of these materials’ comparatively poor resistance to elevated temperatures. This paper presents the results of an ongoing study to document the performance of FRP-strengthened reinforced concrete beam-slabs exposed to fire. With such experimental results, fireproofing materials have the potential to earn standard performance ratings, which are essential to the design engineer and necessary for the continued increase of FRP applications worldwide. A brief synopsis of existing literature related to FRP behaviour at high temperature is provided, in addition to a review of the current fire endurance criteria for structural members. Two large-scale concrete beam-slab assemblies were strengthened with FRP sheets and protected with a two-part patented fire insulation system. The results of fire tests performed on these specimens are presented herein, with emphasis placed on the temperatures measured in the specimens during fire exposure. The data obtained from the tests served to validate a numerical heat transfer model, which predicts the temperature within a strengthened and insulated reinforced concrete beam-slab assembly. Test results and model data indicate that appropriately designed and insulated FRP-strengthened beam-slab assemblies can achieve fire endurances of four hours or more.

Suppression of Pool Fires Using Halocarbon Streaming Agents

Handheld FM-200, FE-36, CF3I and Halotron I extinguishers with 2B:C, 5B:C and 10B:C ratings (or equivalent) were tested for extinguishing Class B heptane pool fires in small and large enclosures (45, 120 and 21000 m3). Test results showed that the Halotron I and CF3I extinguishers performed better than the FE-36 and FM-200 extinguishers. The concentrations of the halocarbons and acid gas by-products in the operator breathing zone and surroundings were measured during the tests. Measurements showed that the agent concentrations were below the levels that would pose life or health risk to the operator. The concentrations of acid gas by-products generated during suppression, however, were at dangerous levels in the small enclosures (45 and 120 m3). Heat flux towards the operator was also measured. Heat exposure presented a severe hazard to the operator during the pool fire suppression. Test results indicate some potentially hazardous conditions to an unprotected operator.

Review of Total Flooding Gaseous Agents as Halon 1301 Substitutes

This paper provides a review of total flooding gaseous agents as Halon 1301 substitutes. Agents are compared, based on published data, in terms of their environmental impact, toxicity, fire suppression performance, and acid gas production from small-to full-scale tests. These data are also collected in tables. Acceptability of an agent by regulatory authority is mostly determined by agent toxicity. Based on the toxicity criteria set by the U.S. Environmental Protection Agency (EPA), five commercial halocarbons (FC-218, FC-3-1-10, HFC-23, HFC-227ea, and HCFC Blend A) and three commer cial inert gases (IG-01, IG-55, and IG-541) are acceptable for total flooding in normally occupied spaces. They are less effective by weight or volume than Halon 1301, with additional limitations and weaknesses. Language: en

Fire Suppression with Inert Gas Agents

Total flooding fire suppression tests of pure argon (IG-01) and an inert gas mixture (IG-541) were conducted in a 121 m 3 compartment with simulated electronic- cabinet fires, wood-crib fires, liquid-pool fires and spray fires. Both agents extinguished the test fires by reducing the oxygen concentration in the compartment. Small fires were challenging to extinguish while large fires were easier to extinguish. The oxygen concentration in the compartment fell t o below 10% in some of the tests with large test fires. IG-541 was uniformly distributed throughout the compartment during the tests. The distribution o f argon became stratified during the tests.

Production Of Carbon Monoxide During Fire Suppression Using Halon Replacements

During full-scale fire suppression tests, halon replacement agents (HFC-227ea and HCFC Blend A) were observed to produce an increased quantity of carbon monoxide (CO), in addition to the production of halogenated compounds. Agent-flame interaction resulted in the increased CO production in the fire tests. CO inhalation has been considered as an important cause of incapacitation in many fire incidents. Therefore, future risk assessment of potential exposure to toxic gases generated during fire suppression using halon replacements should include not only the toxic effect of halogenated compounds but also the toxic effect of CO and their combination.