Smart suits keeps chopper crews warm in freezing water, cool in hot working conditions
April 11, 2008 Safety clothing might be imperative for some jobs, but when it becomes a hindrance and makes work uncomfortable and annoying, it needs to be reassessed. Take the orange safety suits worn by helicopter crews working on oil platforms off the coast of Norway - they're designed to stop the wearer from drowning or freezing to death if their choppers crash-land into the freezing ocean - but the properties that make them effective insulators also make them incredibly hot and sweaty to work in. Enter Helly Hansen's smart suit, impregnated with micro-particles of paraffin wax. The wax slowly melts as body temperatures increase, gradually sucking heat away from the body to cool the wearer through the day, making it much more comfortable. And if the wearer is plunged into icy water, the wax releases stored heat as it solidifies, allowing the suit to be even more effective at the safety component of its job.
Ever since the “Oil Age” came to Norway, platform workers have been easily recognizable in the heliports at Norwegian airports as they troop out to waiting helicopters in bright orange suits that will keep them from either drowning or freezing to death in the event of an emergency landing or a helicopter crash-landing at sea.
But existing suits, while effective in their survival capacity, had a serious problem. The offshore workers felt that they were being “boiled alive” in the helicopters on warm summer days. At the same time, they feared that the original suits did not offer complete protection against heat loss during long periods in cold seawater.
A working group was established to define and clarify what seemed to be conflicting requirements for a new suit - among other things, it had to be cool and comfortable in day-to-day use, but have exceptional heat insulation properties when the wearer is submersed in freezing water.
Norwegian clothing manufacturer Helly Hansen, in partnership with research institute SINTEF, immediately started work on developing a new helicopter suit that would include solutions for all the new items on the long list of specifications.
Among other points, these innovations covered protection against spray on the face, sizes for large and small individuals, a breathing lung, emergency beacon and the ability to turn the wearer the right way up in the sea.
Using SINTEF's existing knowledge on smart wear, the partnership came up with a suit that complements the body's processes for heating and cooling.
A core component of the new Norwegian helicopter suit is a commercially available textile that contains tiny in-woven capsules. These are filled with microscopic particles that consist of a specially developed type of paraffin wax.
If the skin temperature of the wearer of the clothing rises above 28 degrees Celsius, the wax changes phase from solid to liquid.
“Melting requires heat, which the wax takes from the body, cooling the wearer in the helicopter cabin on warm days”, explain product designers Kristine Holbø and Jarl Reitan of SINTEF Health Research.
“In the laboratory, we have demonstrated that the skin temperature of the wearers does not rise by much. We registered that our test subjects did not begin to sweat until as long as 80 minutes at an air temperature of 27 degrees, because the melting process actually lasts such a long time” says senior scientist Hilde Færevik, also of SINTEF Health Research.
An analogy from everyday life is a glass of water with ice-cubes. Until all the ice has melted, the water in the glass remains at the melting temperature of ice, i.e. zero degrees Celsius. Only when all the ice has thawed will the temperature of the water begin to rise.
The laboratory studies also showed that the subjects felt much more comfortable in the new suits than the old ones.
At the same time, Færevik and her colleagues at SINTEF have documented that the new suit offers good protection against loss of heat when the wearer is in the sea.
“We believe that this is both because the paraffin wax releases the stored heat as it returns to the solid state, and because the suit contains extra insulation at the places where the body releases most heat,” she explains.
The suit ensures that the skin temperature of the wearer never falls below 15 degrees anywhere on the body in the course of six hours in water at a temperature of two degrees Celsius.
This ensures, for example, that helicopter passengers retain their ability to grasp things during long involuntary stays in the sea.
Warm hands and feet also provide a direct line to the core body temperature - using the same theory as the AVAcore cooling glove, ensuring that heat is evenly distributed to all parts of the body, which is important for survival and for the ability to make a contribution to one's own rescue.
“Critical voices claimed that the new requirements would make the suits too bulky, but by intelligent distribution of the insulation, we have avoided that they take up too much room”, explains Jarl Reitan.
The suits are already proving themselves a commercial success: in tough competition with recently developed clothing from foreign manufacturers, the Norwegian suit was victorious in a call for tenders from StatoilHydro, the first oil company to swap its old helicopter suits for the new variety.