Since the advent of automobiles, first responders have typically had the luxury of seeing gas fires. Whether it is smoke or flames, such fires are noticeable on approach. First responders can smell leaking fuel and might even be able to see fuel on the ground. But this isn't the case for hydrogen.

Hydrogen is an odorless gas, and the flames can be nearly invisible during the day time. Seeing the flames produced by a hydrogen fire is crucial to first responders, as well as anyone working around a hydrogen-gas process.

More and more people are looking at hydrogen-fueled vehicles as a solution to rising gas prices. This means new challenges for first responders.

Hydrogen is a relatively new choice for automotive use and it will take time to resolve the safety issues. Safety issues involving gasoline-fueled vehicles have been ingrained into society over the past 100 years. The basic knowledge about hydrogen safety is only in its infancy.

One of the major issues with hydrogen-vehicle crashes most likely will be fire, as it is with gasoline-fueled cars. But first-responders won't be able to see these flames, potentially increasing their response times and injury risk.

Many departments already have a thermal-imaging camera that can be used to see hydrogen flames. But the high cost of these cameras usually limits most departments to having only one — and this means that potentially only one person can see the fire. But by using a recently developed device, everyone responding to a scene where hydrogen is present will be able to see the flames.

A New View

Researchers at the University of Vermont are developing the Ultra-Violet Visualization Device (UVVD). This new device takes well-known optical systems and combines them with cutting-edge fiber-optic technology. By combining specialized fiber-optic material with a binocular-type optical system, UV light can be converted to visible light without the need for expensive and bulky optics. UV light is one of the signatures of hydrogen flames and is outside of the visible spectrum. The UVVD could lead to a more efficient way for first responders to see the potentially dangerous flames.

There were two key objectives when the design criterion was established. The first objective was that the design should be able to operate without any outside power. Designing the UVVD to operate without batteries means it can be stored on emergency response vehicles and used at anytime without adding another item to the daily checklist. The UVVD's small design also allows it to be carried at all times by personnel working in or around any hydrogen facility. The second objective was that the design must be relatively cheap. An inexpensive design allows the opportunity for a much wider implementation, and that is the most important part of the entire project.

First responders to car accidents most likely will need to see flames only when they are within 50 feet. As a result, the UVVD can be designed with optics similar to small binoculars. This will keep the UVVD small and lightweight. The design will allow the first responder to focus on an area of concern, but be a safe distance away. The fiber-optic material allows visible light to pass through as well, just like normal binoculars. The image coming through the device is not distorted, and the first responder will be able to establish what he is seeing easily.

The design has been successfully tested in a laboratory setting to prove UV light can be imaged. However, adequate testing and development need to be performed in order to establish whether or not the device will execute as designed under the variety of conditions first responders face.

UV Concerns

One of the major concerns is whether the UV light produced by the flames will be strong enough to affect the fiber-optic material. A hydrogen fire will produce adequate light, but it is yet to be determined if this will occur at a safe viewing distance. The engineers at UVM have considered some of these concerns and have created variable designs to remedy the issues. One modification that can be made to the device in order to let first responders see a hydrogen flame would be to configure it to only look for UV light. By using the UVVD first as binoculars to focus on an area of concern, then switching to only look for UV light, the first responder can thoroughly check an area. This feature may be a critical tool for industrial firefighting, where small flames may be present in areas not seen by flame detectors. This ability may provide first responders a way to locate a fire more rapidly.

The UVVD won't replace a thermal-imaging camera, but may provide all first responders with another tool to help protect themselves and others. By being both small and inexpensive, the UVVD will enable fire departments the ability to provide more than one person with the device. And by providing more than one first responder with the ability to assess the scene the time to remedy the situation most likely will decrease. There always will be a threshold for what is economical and what is not when it comes to buying equipment. Right now, providing all firefighters with a thermal imager is not under the threshold, but providing them with a UVVD may be.

James McLean is pursuing his Ph.D. in mechanical engineering at the University of Vermont. His research is focused on hydrogen fire safety. McLean has a master's in fire-protection engineering and a bachelor's in mechanical engineering, both from Worcester Polytechnic Institute.

Dryver Huston has been a mechanical-engineering faculty member at the University of Vermont since 1987. He has seven U.S. patents and recently has authored a book entitled Structural Sensing, Health Monitoring and Prognosis. Huston has a Ph.D. and a master's from Princeton University and a bachelor's from the University of Pennsylvania.

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