Hot Surface Ignition Temperature of Dust Layers with and without Combustible Additives

An accumulated combustible dust layer on some hot process equipment such as dryers or hot bearings can be ignited and result in fires when the hot surface temperature is sufficiently high. The ASTM E 2021 test procedure is often used to determine the Hot Surface Minimum Ignition Temperature for a half inch deep layer of a particular dust material. This test procedure was used in this thesis to study possible effects of combustible liquid (such as lubricating oil) and powder additives in the dust layer as well as air flow effects. The following combustible dusts were used: paper dust from a printing press, Arabic gum powder, Pittsburgh seam coal, and brass powder. To develop an improved understanding of the heat transfer, and oxygen mass transfer phenomena occurring in the dust layer, additional instrumentation such as a second thermocouple in the dust layer, an oxygen analyzer and gas sampling line, and an air velocity probe were used in at least some tests. Hot Surface Minimum Ignition temperatures were 220oC for Pittsburgh seam coal, 360oC for paper dust, 270¡Ãƒâ€° for Arabic gum powder, and \u3e 400oC for brass powder. The addition of 5-10 weight percent stearic acid powder resulted in significantly lower ignition temperature of brass powder. When combustible liquids were added to the dust layer, the ignition temperatures did not decrease regardless of the liquids¡¯ ignitibility because the liquids seemed to act as heat absorbents. Although air velocity on the order of 1 cm/s did not affect test results, much larger air velocities did affect the results. With 33 cm/s downward airflow at the elevation of the surface of the layer, Pittsburgh seam coal was not ignited at 230¡Ãƒâ€° which was 10¡Ãƒâ€° higher than the 220¡Ãƒâ€° hot surface ignition temperature without airflow. Based on the results and data from the additional instrumentations, modifications of the ASTM E2021 test procedure are recommended

Enhancing Building Fire Safety Performance by Reducing Miscommunication and Misconceptions

Building fire safety is driven by regulations and technical building codes, at least as a minimum requirement. As fire protection engineers (FPEs) design fire safety measures based on requirements in the regulations, they are often viewed as the primary agents in ensuring the fire safety of buildings. However, their mission often starts with given building design features, such as interior spatial layout, exterior shape, site plan, and so forth, which are mostly determined by architects. The only exception is where the FPE is invited to assist in the project planning, feasibility and early concept design stages of a project. Regardless, architects also can influence building fire safety performance, whether or not they explicitly acknowledge or understand this. Although architects design buildings within the boundaries of the regulatory requirements, the architect’s focus is often related to the visual and spatial aesthetics of buildings linked to building form and functionality, which are not subject to the regulations. These aesthetics can sometimes compete with fire safety objectives. As such, buildings can be unsafe in certain situations due to unintended effects of building design features on actual fire safety performance. This research describes the relationship between architecturally conceived building design features, design expectations for fire safety systems, and the actual or conceivable fire safety performance of the building. Steps are proposed that FPEs can take to identify and address potentially competing objectives and deliver increased fire safety performance

Conceptual Model Development for Holistic Building Fire Safety Performance Analysis

The evaluation of building performance during fires is a critical step in designing appropriate strategies. Inappropriate or incomplete performance evaluations can mislead fire safety design solutions, which may in turn result in unacceptable loss of life or building damage from fire. While various building fire safety performance evaluation models have been developed, they focus primarily on ‘hard’ characteristics, such as building construction type and fire protection measures. However, ‘soft’ characteristics, such as building design (architectural) features and occupant characteristics, which also significantly influence building fire safety performance, have not been comprehensively taken into account. In the current study, two conceptual performance models: a generic fire response model and an integrated characteristic interaction model, have been developed to represent the holistic building fire safety performance considering the effects of both hard and soft characteristics. In these models, various cause-effect relationships among building, people, and fire characteristics are identified at the different levels of detail. Based on the conceptual models, a quantitative model utilizing the parameter ranking method and weighted sum method, which are commonly used in analytical hierarchy process, is proposed as a tool to help evaluate building fire safety performance and to assist decision making process of developing fire safety design solutions

An Experimental and Modeling Study on the Effect of Wall Opening Location on the Under-Ventilated Compartment Fire

An experimental and modeling study was carried out to investigate the effect of wall opening location on the mass flow rates of gases through the opening and the associated fire phenomena, such as compartment temperature, projected flame height through the opening, and the heat release rates inside and outside the compartment. A 0.3 m by 0.3 m opening was placed at three different elevations—bottom, middle, and top—of a narrow end wall of a 0.8 m by 1.2 m by 0.8 m (H) compartment. A propane gas burner was used to provide four different fire sizes in the compartment: 90, 110, 130, and 150 kW. The existing correlations for mass flow rates and heat release rates generally do not include the wall opening location as a variable and are functions of only the opening area and height. Based on the experimental and modeling analysis, it is found that the wall opening location affects the internal and external fire phenomena. Two fundamental factors, K and O, are introduced to explain the effect quantitatively. Factor K is the ratio of the air inflow predicted by Fire Dynamics Simulator (FDS) to the existing correlation (0.5AoHo), and Factor O is the ratio of the oxygen consumption rate in the compartment to the oxygen flow rate into the compartment, indicating combustion efficiency. Factor K ranges from 0.78 to 0.94, and O ranges from 0.67 to 0.85 for different opening locations, which suggests that the existing correlations may overestimate the amount of airflow to and the combustion efficiency within the compartment

The Effect of Environmental Moisture Conditions on the Calculated Incident Radiant Heat Flux by Plate Thermometers

This study investigates the effect of environmental moisture conditions on the calculated incident radiant heat flux (irradiance) by plate thermometers (PT). Alterations were made to the moisture content of the PT insulation layers to achieve these conditions. Irradiance was calculated using a pre-determined equation based on fully insulated conditions and validated using a Schmidt-Boelter radiometer. The study consisted of two phases; (i) investigating the effect of preheating PT to the accurate irradiance, (ii) investigating the effect of moisture in the PT on the measurement of irradiance. Calculated irradiance agreed with measured for preheated PT, but not with unheated PT. Four representative moisture conditions were identified for phase two, whereby samples were equilibrated at 0, 45, 65, and 98 wood moisture equivalent (%WME). No noticeable difference identified between measured and calculated irradiance was detected within 0–65%WME. PT with 98%WME showed a difference between the irradiance as the moisture inside the PT insulation absorbed energy from the PT to vaporize. Therefore, using preheated PT with any %WME under 65 is recommended to obtain accurate enough irradiance measurements. The result can use to improve determining the fire spread mechanisms and accurate measurements of irradiance in outdoor fires such as informal settlements fires

Design parameters of free-form color splitters for subwavelength pixelated image sensors

Summary: Metasurface-based color splitters are emerging as next-generation optical components for image sensors, replacing classical color filters and microlens arrays. In this work, we report how the design parameters such as the device dimensions and refractive indices of the dielectrics affect the optical efficiency of the color splitters. Also, we report how the design grid resolution parameters affect the optical efficiency and discover that the fabrication of a color splitter is possible even in legacy fabrication facilities with low structure resolutions

Negligible Effect of Quercetin in the Pharmacokinetics of Sulfasalazine in Rats and Beagles: Metabolic Inactivation of the Interaction Potential of Quercetin with BCRP

Breast cancer resistance protein (BCRP) mediates pharmacokinetic drug interactions. This study evaluated the potential of quercetin to inhibit and induce BCRP in vitro and in vivo. The inhibition of BCRP was investigated for quercetin and its metabolites using BCRP/mBcrp1-overexpressing MDCKII cells by flow cytometry. The induction of BCRP was investigated in LS174T cells using quantitative PCR. The expression of rat BCRP in rat small intestine, liver, and kidney was also measured after multiple administrations of quercetin in rats (50, 100, and 250 mg/kg, seven days). The in vivo pharmacokinetic changes of sulfasalazine following single or multiple administration of quercetin in rats and beagles were investigated. Although the induction effect of quercetin on BCRP was observed in vitro, the in vivo expression of rat BCRP was not changed by multiple quercetin administrations. Oral administration of quercetin did not affect the plasma concentration or pharmacokinetic parameters of sulfasalazine, regardless of dose and dosing period in either rats or beagles. In addition, the inhibitory effect of quercetin metabolites on BCRP/mBcrp1 was not observed. These results suggest that the in vivo drug interaction caused by quercetin via BCRP was negligible, and it may be related to the metabolic inactivation of quercetin for the inhibition of BCRP

First detection of the amphibian chytrid fungus Batrachochytrium dendrobatidis in free-ranging populations of amphibians on mainland Asia: survey in South Korea

Chytridiomycosis, a disease that has caused amphibian population declines globally and elevated many species of anurans to endangered or threatened status, has recently been declared an internationally notifiable disease. Batrachochytrium dendrobatidis (Bd), the amphibian chytrid fungus causing this disease, has not been previously reported in Korea or on mainland Asia. Thirty-six frog specimens representing 7 species were collected from the wild in South Korea and examined for Bd using standard PCR. Bd was detected in 14 (38.8%) samples from 3 species (Bufo gargarizans, Hyla japonica, and Rana catesbiana). Skin sections from all 14 PCR-positive frogs were examined\ud using 2 staining techniques: haematoxylin and eosin (H&E) and Bd immunoperoxidase (IPX). In histological sections, zoosporangia were found in 6 frogs, with lower sensitivity for H&E (21%) than for IPX (46%). Intensity of infection, based on histopathology, was low in all frogs. These results confirm that Bd is present in South Korea and, hence, on the Asian mainland. Studies are urgently required\ud to determine the impact of chytridiomycosis on Korean amphibians, and to map the distribution of Bd in Korea and other Asian mainland countries