NATICK, Mass., Hawaii, June 6, 2005 – Once you hear the slight puff and see the yellow flame mellow into a glowing blue, you know the capillary force vaporizer has gone into action.
The vaporizer is a breakthrough in burner technology being applied to the modular individual water heater, a jointly developed product of the Department of Defense Combat Feeding Directorate's Equipment and Energy Technology Team at the U.S. Army Soldier Systems Center here, and Mountain Safety Research (MSR), a division of Cascade Designs, Inc. in Seattle, Wash.
Trioxane fuel bars had been the source for warfighters to heat water for beverages, dehydrated rations and personal hygiene, but there were drawbacks and production has been discontinued, said Leigh Knowlton, project officer.
"Soldiers had supply problems because they're considered fuel and ordered separately from food. It will also evaporate if the seal is broken in storage and can give off noxious fumes when burned," he said.
Knowlton said little has changed in the last 40 years in this area of warfighter sustainment. Current authorized equipment to heat water consists of a plastic canteen, steel cup, cup stand and cover.
Absent the fuel bar, the alternative is the military's squad stove, a commercial product that has an external fuel tank with a pump to build pressure and prime the stove.
"It's heavy because of the bottle, has a lot of moving parts, it's expensive, and it's not about efficiency-it blasts out heat," Knowlton said. "If you can use less fuel, that's less fuel to carry."
Meal, Ready-to-Eat (MRE) rations have a flameless heater for the entrée and upcoming pouches to make hot beverages, but there's still a void for the dried foods found in the Long Range Patrol/Cold Weather Ration, which require 28-40 ounces of hot water for all the components.
He said the situation will worsen if the canteen cup is phased out because of the increasing popularity of bladder hydration systems.
With no existing commercial stove or water heater that's lightweight, compact, compatible with on-the-move hydration systems and meets the military's requirement to burn JP-8 fuel, the capillary force vaporizer invented by Vapore, Inc. in Richmond, Calif., became the solution.
About the size and shape of a pair of antacid tablets, the three-layer vaporizer held together by an impermeable exterior glaze has no moving parts and fits inside a cone-shaped stove where it converts liquid fuel into a pressurized gas.
Knowlton said the vaporizer is durable as well, working for hundreds of hours before wearing out.
A coarse ceramic layer at the bottom is the feed wick that touches the fuel. In the middle is the boiler wick, a fine ceramic layer that generates high capillary pressure and vaporizes the fuel.
On top is the orifice disk that conducts heat from the flame to the boiler wick and has one or more pinhole-sized openings to expel fuel vapor.