Occupational Health & Safety

Innovative Uses of Thermal Imaging

With so many applications, the use of thermal imagers will only continue to rise as the technology becomes more affordable.

IN the workplace, excessive amounts of heat emitted by machinery or escaping from containers can be a sign of something more serious. Most plants, factories, and businesses have processes in place to protect workers from the potential rupture or explosion of deteriorating machinery. However, these procedures often are limited in their effectiveness.

Manual checks of machinery conducted in the morning might be too early to catch a rupture that happens later in the day, and there is a limit to the monitoring ability of safety staff. They can be in only one place at a time. Such processes (which are marginal at best) are safe only to a limited degree, but, with thermal imaging, businesses can add a level of safety to protect workers and business assets.

The example of a petroleum cracking and processing plant will be used to illustrate the potential dangers of overheating equipment. The high temperatures of the petroleum in a petroleum cracking and processing plant normally are kept in check by steel containment vessels with a refractory lining. The integrity of that lining is the only thing separating workers from exposure to dangerous gases and the potential of a vessel rupture and subsequent damage to the plant.

To ensure the integrity of the lining, safety personnel regularly check the external heat levels of the vessels, measuring levels on each of the plant's containment vessels, one by one. A technician uses equipment that maps the temperature on the outside of the vessel and makes a printout. If a particular area of a vessel is deemed to be too hot, it can be cooled internally, or the entire process can be stopped while crews make repairs.

Constant Vigilance
With a thermal imager monitoring each containment vessel, safety checks are conducted constantly, 24-hours a day. Because a thermal imager detects heat levels, it can be integrated into a monitoring system that will trigger alarms or other forms of notification if a temperature on one of the vessels exceeds a safe level. Use of thermal imagers enables a plant to monitor all of the vessels simultaneously in real time, and it incorporates monitoring system integration and eliminates the potential for human error.

In industrial plants, engineers, inspectors, and managers use thermal imagers to spot a host of potential problems, such as overheating electrical circuits, ducting failure, hot bearings, or dangerous heat levels for chemicals, before they develop into major problems that can cause extensive damage and lead to expensive repairs. Manufacturing companies use them to monitor infrastructure for hot spots, while utility companies use thermal imagers to monitor their lines for preventive maintenance. Thermal imaging allows for non-destructive and non-invasive monitoring of machines and processes. It provides process control for manufacturers of steel, aluminum, glass, and food, to name just a few.

The Obstacles
At present, use of thermal imaging as a safety tool has been limited, due, most likely, to a lack of awareness by safety systems integrators. Many on-site safety personnel are aware of the benefits of thermal imaging, but safety systems integrators and suppliers have not yet begun making thermal imaging technology available on a widespread basis.

Another concern is the perceived expense of thermal imagers. In recent years, the technology has become significantly more cost-effective. In addition, the purchase of thermal imagers can be easily justified through the prevention of damage to property and injury to workers. Avoiding one serious injury could be the justification for the purchase of multiple thermal imagers, based simply on an injury cost model.

While thermal imagers are more expensive than visible light cameras, it is important to review multiple variables when researching cameras to purchase. Considerations should focus on what other provisions would have to be made to get visible cameras to do the job. Will added lighting be necessary? If so, it should be understood that additional lighting could cause confusing light patterns that reduce the effectiveness of visible light cameras. Is the correct power source already in use, or will the factory have to be retrofitted to handle the new cameras? Ultimately, an initially less expensive visible light camera system could end up costing as much or more than a thermal imaging system, and the safety made possible with the thermal imaging system would almost assuredly be higher.

For organizations interested in the purchase of a thermal imaging system, some basic considerations should be made first. With any camera system, the first consideration is compatibility with existing video and image processing systems--i.e. do they have the right outputs and power inputs, and are they compatible with environmental enclosures that might be readily available? Another major consideration should be the requirements of the camera. For organizations looking for minute details in heat measurement, higher resolution is important. For organizations interested in measuring only surface elements and simple changes in temperature, a lower resolution camera will suffice. Typically, prices tend to increase along with resolution.

In general, thermal imagers, no matter what the resolution, tend to offer high levels of safety to workers in industrial settings and even the local communities. Avoiding a rupture or the release of toxic gases into the air benefits everyone.

Outside of heavy industry and manufacturing, there are several other areas where thermal imaging continues to play a key role in increasing safety.

A Host of Applications
Thermal imaging technology is utilized in the full spectrum of firefighting requirements, including scene sizeup, in-fire attack, search and rescue, hazmat assessments, and post-fire overhaul. Cameras equipped with thermal imaging technology assist in spotting holes in flooring or other structural weaknesses, warning firefighters before their lives are endangered.

After a fire has been extinguished, a thermal imaging survey during overhaul can detect unseen embers and other lurking dangers and serve in the investigation of the fire's cause. The life-saving benefits of thermal imaging technology aren't just limited to structure fires. Firefighters and law enforcement professionals find them invaluable in rapid assessment of motor vehicle accidents, wildfires, and industrial and petrochemical fires.

Public safety and law enforcement personnel equipped with thermal imaging technology possess a powerful, proven arsenal of life-saving and crime-detection tools. Officers can use thermal imaging technology to conduct hidden compartment searches, perimeter surveillance, marine or ground surveillance, safer flights, structure profiling activities, fugitive and rescue searches, disturbed surface investigations, pollutant searches, and vehicle pursuits, all without exposing themselves to additional danger.

Thermal imaging also is used for facilities security. Thermal imaging security systems are passive and non-intrusive. The cameras can see through pitch-black darkness, spot an intruder in most weather conditions, and see over long distances. Thermal imagers aren't affected by lights like traditional surveillance methods. With thermal imagers, no ambient light is necessary to see in the dark. Lighting can be ineffective at highlighting intruders at a distance or hidden in brush. It also calls attention to a facility and its perimeter. Lighting can indicate the direction in which security guards or cameras are looking, and, just as importantly, where they are not looking. With thermal imagers, the advantage goes to the guards, helping to improve their safety by giving them increased information and reducing the threat of attack or infiltration.

One of the most practical and potentially exciting uses of thermal imaging technology is in transportation. All drivers, even the most skilled, face a special problem at night--they often cannot see what should be a routine hazard or obstacle until it is too late to avoid it. Vehicles equipped with thermal imaging capabilities help a driver see three to five times farther than conventional headlights. Night-driving vision can be extended to 1,500 feet or farther. This gives drivers up to five times as much time to react.

In addition, because thermal imaging is not affected by light, drivers can "see" past oncoming headlights. According to the National Highway Traffic Safety Administration, the night-driving fatality rate doubles during the period of time from 9 p.m. to 6 a.m., and nearly 13,000 people are killed annually in nighttime crashes. Thermal imaging technology extends driver reaction times and makes the roads safer. For companies that employ drivers who drive at night, thermal imaging could increase the level of safety for those drivers.

Prices for Imagers Falling
Thermal imaging as a safety tool continues to grow in popularity. Over time, this growth is likely to result in additional technology improvements and reductions in price. Such improvements would serve to increase the quality and availability of the technology, making it easier for organizations to obtain. In the meantime, companies interested in increasing the level of safety for workers should consider thermal imaging and its potential benefits for their needs.

This article originally appeared in the November 2004 issue of Occupational Health & Safety.

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