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Technics

Brief notes about the world of science and technology at Southwest Research Institute


Trash Can Fires That Put Themselves Out

Engineers in the Department of Fire Technology at SwRI have developed a novel device that promises to substantially reduce one of the leading causes of fires in the world. According to the National Fire Protection Association, hundreds of lives are lost and millions of dollars in property damage are incurred annually in the U.S. alone as a result of fires originating in trash cans.

Through an internal research program, SwRI has developed a prototype fire extinguishing waste can liner system known as FireTrapTM (patent pending). The device uses shrink film to passively (without human intervention) smother trash can fires before they can spread.

Senior Research Engineer Kent R. Farmer, inventor of the FireTrapTM concept, explains that shrink film was a natural candidate for this application because of its inherent thermophysical properties -- on exposure to sufficient heat, the material dynamically converts thermal energy to mechanical force. In waste can fires simulated at SwRI, as the fire began to develop, the FireTrapTM liner system sensed the heat and forcibly collapsed around the fire, depriving it of the oxygen necessary for continued combustion.

Shrink film is used in packaging to protect products from contaminants and also in the electronics industry in the form of shrink tubing to seal and insulate electronic connections.

During the project, Farmer developed two full-scale prototype liner designs that successfully extinguished 10-kW waste paper fires in 13-gallon trash cans.

"We chose a 13-gallon capacity can for our tests," says Farmer, "because research indicated that this size is one of the most common found in homes and offices. Development of the prototype liner system began by first conducting a series of experiments to quantitatively define the thermal environment generated by a typical trash can fire under various realistic fire loading conditions."

Farmer explains that transient temperatures and heat fluxes during the initial fire build-up phase, the most critical period, were measured and used as boundary conditions in an analytical optimization procedure. "The analysis allowed us to zero in on a theoretically successful design," he notes, "and subsequent experiments proved the system capable of extinguishing fires within seconds after the film sensed the heat.

"Additional research is needed to refine the concept and develop marketable products," he adds. "The complex variables associated with real-world fires of this type must be fully quantified and appropriate FireTrapTM designs developed for each scenario. Nevertheless, our initial results have proven the concept and provide a sound basis for future research."

Baldwin Named ASME Fellow

Richard M. Baldwin, a senior research engineer in the Institute's Mechanical and Fluids Engineering Division, has been elected a Fellow of the American Society of Mechanical Engineers (ASME).

Baldwin has served ASME as the San Antonio section chairman and chair of several committees and is a reviewer on the International Gas Turbine Institute Controls and Diagnostics Committee.

Baldwin came to SwRI in 1973 after service in the United States Air Force. His technical focus at the Institute has been analytical studies of rotating machinery, and he developed microcomputer programs for long-term monitoring of machinery vibrations and for field balancing.

He holds a bachelor's degree in engineering science from Trinity University in San Antonio and a master's degree in mechanical engineering from the Georgia Institute of Technology. He is a registered professional engineer in the state of Texas.

Institute Unveils Fire Permeability Test Facility

Automobile manufacturers are using plastic fuel tanks and fuel system components instead of traditional metal components to accommodate new automobile designs. As a result, state and federal environmental regulations have been enacted because fuel vapor inside can penetrate the plastic tank barrier layer and contribute to regulated evaporative vehicle emissions. To meet new testing requirements, SwRI is building a 2,000 square foot Permeability Test Facility to evaluate hydrocarbon emissions from plastic fuel systems, making the Institute one of the few research and development organizations capable of performing indoor vehicle fire test and permeability evaluations.

"Car manufacturers are requiring their component suppliers to verify that their products will meet state and federal government standards for permeation," says Alex Wenzel, director of the Department of Fire Technology. "The Institute is in a unique position to provide component and complete vehicle hydrocarbon vapor emissions measurements and a variety of automobile fire performance evaluations."

The permeability facility houses two sample chambers designed for component or fuel system evaluations of hydrocarbon emissions and speciation chromatography. The chambers are equipped with variable temperature control, from -40 degrees Celsius to 82 degrees Celsius, to simulate temperature changes in the environment. A 1,280-cubic-foot soak chamber is used to store test samples at 40 degrees Celsius during the performance testing cycle.

Data acquisition devices, analyzers, and operations are run from a control room inside the facility. Durability tests include pressure/ vacuum, slosh, and vibration analyses. The new facility will expand SwRI's services for the automotive industry. Existing services include full-scale emissions testing, vehicle and engine design and development, systems and component testing, emission reduction and qualification analyses, instrumentation development, fluids testing and qualification, materials specification and evaluation, manufacturing technology, and process and safety engineering.

South Texas Manufacturers Gain a Competitive Edge

Under the direction of the Texas Department of Commerce and the National Institute of Standards and Technology, the Texas Manufacturing Assistance Center (TMAC) is successfully providing small manufacturers in South Texas with industrial and manufacturing engineering expertise.

The South Central TMAC office, located and operated by Southwest Research Institute, is one of five regional offices established in March 1995 to encourage the use of appropriate techniques in small businesses. The other four Texas regional offices are operated by the Texas Engineering Extension Service at Texas A&M University, the Automation and Robotics Research Institute at the University of Texas at Arlington, the Institute for Manufacturing and Materials Management at the University of Texas at El Paso, and the University of Houston.

"Consistent with the Institute's charter of technology transfer, SwRI is helping smaller manufacturers adopt appropriate technologies to make them more competitive in the global marketplace," says Michael Grant, director of the South Central TMAC office. "We have worked with more than 200 companies, from food processing to furniture manufacturing firms, providing affordable engineering support."

One of the companies, Alamo Packaging Corporation (APC), used to shut down its computer files for 10 days to complete its year-end inventory reconciliation. APC materials manager Priscilda Garza was interested in streamlining the inventory process. TMAC field engineer Rod Cantu worked with Garza and warehouse personnel to develop a process that allowed APC to download inventory information into a spreadsheet and create a user-friendly inventory system in the warehouse that sorted parts by aisle. To make the process even more efficient, APC attached bar code labels for each part to the inventory form, increasing the speed and accuracy of data entry.

"Physical inventory has never run as smoothly," Garza says. "With TMAC's proposed labels and scanners, Alamo Packaging will continue to improve inventory procedures."

Some of the services available from TMAC include assessment and benchmarking of existing operations and assistance in providing access to specialized technology. These are areas where small companies are often at a competitive disadvantage. TMAC also provides technical education seminars and workshops.

TMAC monitors the usefulness of its services by measuring increased sales and profits, exports, job growth, and operational efficiency in the companies it assists.

Converting Jet Fuel for Commercial Aircraft

SwRI is assisting Sasol Oil (Pty), Ltd., a South African-based oil company, in evaluating the company's synthetic and semi-synthetic hydrocarbon-based jet fuels for use in commercial aircraft at Johannesburg International Airport.

"The Institute will provide independent consultation for Sasol Oil," says SwRI project manager Leo L. Stavinoha. SwRI has considerable international experience in analyzing and evaluating alternative fuels.

Currently, international commercial aircraft refueling at Johannesburg are supplied with petroleum-based Jet A-1 fuels from crude oil refineries within the Republic of South Africa. Sasol Oil markets a range of synthetic fuels produced from coal by their sister company, Sasol Synthetic Fuels (Pty), Ltd. They believe that their synthetic and semi-synthetic jet fuel can compete in quality with conventional petroleum-based fuel in response to increased demands for jet fuel, especially at the Johannesburg Airport.

Commercial aircraft fuels are required to meet internationally accepted standards such as the International Air Transport Association (IATA) Guidance Material for Aviation Turbine Fuels, Def. Stan. 9191 Issue 2 (formerly known as DERD 2494) standard requirements, and American Society for Testing and Materials (ASTM) D1655 specification requirements. The Sasol synthetic and semi-synthetic jet fuels meet all standards for conventional jet fuel. This is the first commercial attempt to qualify synthetic and semi-synthetic jet fuel coordinated with ASTM and IATA.

"Phase One of the project," says Institute Engineer Dr. Clifford A. Moses, "includes discussions and consultations with the major airframe and turbine engine manufacturers and airline operators that have an interest in the South African market to identify any concerns that would impede market acceptance."

In addition, SwRI scientists will develop the normal international specification requirements data to characterize Sasol synthetic and semi-synthetic fuels and demonstrate their acceptability at the laboratory or bench-test level, which will provide a plan of action for Phase Two.

Although Sasol's synthetic jet fuel has superior properties in terms of cold flow behavior and combustion characteristics, concerns that have previously been identified with highly treated synthetic fuels will be carefully addressed. These include evaluating fuel lubricity and the use of lubricity-improving additives, if necessary; examining elastomer compatibility to ensure that seals do not shrink or swell excessively by maintaining a minimum aromatic concentration; assessing the dielectric constant correlation to fuel density; and ensuring that the fuel is compatibility with jet fuel from other sources.

"Based on the results of this research," adds Moses, "the plan of action, fully coordinated with industry, will be implemented in Phase Two to ensure complete compliance and ready market acceptance of Sasol Oil's synthetic and semi-synthetic jet fuel."

Rapid, Accurate Roadway Incident Detection

Combining military night vision technology with sophisticated computer algorithms, Southwest Research Institute engineers have produced an automatic traffic incident detection capability for use in advanced traffic management systems. The new technology is designed to provide rapid, accurate incident detection, day or night, under varying weather conditions.

Currently available detection devices, such as inductive loop detectors and vision-based systems, primarily detect the congestion associated with an accident or hazard. If traffic is light, incidents may not be detected at all. Existing detectors are also expensive to maintain, slow, and prone to false alarms.

The system developed at SwRI detects traffic incidents through a combination of long wave infrared (LWIR) thermal imaging and image processing techniques. LWIR imaging is capable of measuring the same traffic parameters -- lane occupancy, volume, speed, etc. -- recorded by loop detectors. In addition, thermal images are not affected by darkness, shadows, glare, and clutter, such as freeway signs and billboards, that can make video camera images difficult to process.

The LWIR traffic incident detection system combines the thermal signature of an automobile in operation -- dark (cool) on top and bright (hot) below -- with image processing algorithms to identify vehicle orientation and movement and even the lanes of traffic on a roadway. Overturned vehicles and vehicles traveling the wrong way are recognizable.

To detect anomalous roadway conditions, the image processing system must first possess information regarding the nominal condition of the roadway -- the road with no objects on or near it. This information is embedded in a baseline road image that is compared to subsequent images to determine whether significant differences have developed between the base model and the current images of activity on the road.

Temporal maximum and minimum filtering are employed to track vehicle motion, determine normal traffic lanes, and aid in detecting erratic driving patterns. These filtering techniques retain the peak maximum or minimum values for individual pixels in an image over time. Temporal median filtering, a method for reducing pixel variability over time, and image subtraction techniques are used to detect stationary objects, such as stalled cars, thus allowing the identification of hazards on or near the roadway.

An additional benefit of the thermal imaging system is that it performs well in interchanges and accident-prone areas that cannot be monitored effectively with standard loop detectors.

The system can be used for:

  • Rapid detection of incidents on urban or rural freeways
  • Classification of incidents based on severity estimates (for example, whether an incident occurs in a lane of traffic or adjacent to the roadway)
  • Timely dispatch of appropriate emergency services
  • Prevention of accidents by early recognition of hazards
  • Prevention of secondary accidents
  • Maintaining freeway capacity by rapid clearing of incidents.

Further development and testing of the LWIR traffic incident detection system are under way, and foreign and domestic patent applications have been filed for the technology.

Comet Clues

This photograph of the comet Hale-Bopp was taken at White Sands Missile Range, New Mexico, by SwRI Staff Technician Thomas Booker of the Instrumentation and Space Research Division at 4:30 a.m. (MST) March 19, 1997. Booker is part of an Institute team led by Dr. Alan Stern, assistant director of the Space Science Department, Boulder, Colorado, office, which managed one of four sounding rocket experiments that took spectroscopic measurements of the comet's ultraviolet light. The successful March 29 mission payload looked at Hale-Bopp's coma and tail to measure carbon concentrations and gas emissions using the SwRI-developed Extreme Ultraviolet Spectrograph. These measurements, which may shed light on comet origins and yield clues about the formation of the solar system, cannot be made with ground-based instruments. The payload was launched by the U.S. Navy using a Black Brant 9 rocket for the NASA Goddard Space Flight Facility based at Wallops Island, Virginia.

Published in the Spring 1997 issue of Technology Today®, published by Southwest Research Institute. For more information, contact Joe Fohn.

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