John B. Hoover

Cold-vapor atomic absorption analysis for mercury in the Greenland Sea

Abstract A cold-vapor atomic absorption technique for the analysis of mercury in sea water has been developed and tested. It is adaptable to use on shipboard, and sufficiently sensitive to monitor the mercury content of ocean waters at the rate of 4 to 6 samples per hour. Laboratory analyses show the technique to be capable of 7·7% relative standard deviation with samples of 220 ng/l. Application of the technique to water samples returned from arctic areas have indicated changes in mercury content from the 50 ng/l. typical of open ocean water, to 360 ng/l. for surface waters associated with sea ice.

Critical Evaluation of Rotary Atomizer

Abstract The flammability characteristics of jet fuel aerosols are critical to the development of fire-safe fuels. In efforts to design and characterize fire-safe fuels, an automated rotary atomizer has been constructed to produce fuel aerosols and measure their mist flammability properties. A particle analyzer has been coupled directly to the atomizer to provide drop size distribution information on the aerosols. The size distribution measurements provide crucial evidence regarding the droplet formation mechanism of the constructed atomizer. This paper focuses on the evaluation of water aerosols as a function of disk speed, flow rate to the atomizer, and liquid surface tension utilizing this instrumental design.

Petroleum-Based Hydraulic Fluids and Flammability

Abstract Hydraulic fluids for the most part are considered to be much less flammable than middle distillate fuels. Petroleum-based hydraulic fluids have high flash points, while water-based hydraulic fluids (because of their high water content) are definitely nonflammable. The major problem with water-based hydraulic fluids is corrosion. Petroleum-based fluids are much less corrosive and thus equipment lifetime is considerably increased. However, some petroleum-based hydraulic fluids have been observed to be a fire safety hazard in situations where high-pressure leaks can result in aerosol formation. These fire hazards cannot be adequately explained based solely on flash point considerations of the hydraulic fluids alone.

The Construction of an Improved Automated Atomizer for Evaluating Jet Fuel Flammability

Abstract The flammability characteristics of jet fuel aerosols are significant parameters for the development of fire safe fuels. In our laboratorys efforts to evaluate the success of specific chemical additives designed to reduce the ignition of jet fuel aerosols, we have developed a unique, completely automated atomizer for producing aerosols and measuring their mist flammability properties.

Application of the CFAST Zone Model to Ships — Fire Specification Parameters

An analysis of the sensitivity of the Consolidated Fire and Smoke Transport model to several key fire specification parameters has been performed for this paper. Results of simulations of shipboard fires are compared with data from full-scale experiments. It was found that reasonable estimates of the fire inputs, with the exception of the smoke and carbon monoxide production parameters, could be obtained from literature values. The soot parameter was found to be critical for accurate temperature predictions, especially in the upper layer.

FLAMMABILITY OF AEROSOLS GENERATED BY A ROTARY ATOMIZER

Abstract Flammability of aerosols of hydrocarbon liquids was studied using a spinning disk atomizer, which simulates accidental aerosolization of a fuel from an aircraft. We determined the critical droplet sizes and fuel flow rates (or mass flux) needed to create an aerosol mixture that forms a stable flame upon ignition. At lower droplet sizes or higher flow rates than the critical values the aerosol mixtures were flammable. The critical flow rate increases with the droplet size for JP5 and are lower by a factor of 3 to 5 for heptane. The flammability diagram enables a quantitative comparison of different liquids in aerosol form. This is significantly different from the thermodynamic behavior of a liquid pool, which is dictated by the flash point or vapor pressure.