Agriculture Reference
In-Depth Information
“Bertha” steam autoclaves used by the military. Steam autoclaves are common labora-
tory equipment and undoubtedly are reliable in effecting sterilization through the use
of wet heat, which is the introduction of water/steam at temperatures above 121 °C
and slightly elevated pressures around 17 psi inside a closed, heavily reinforced metal
chamber. Bertha steam autoclaves used by the military weigh over 450lbs (4-man
lift), occupy a large footprint (60.1ft
3
), require 9kw of electricity and 5 gallons
(640 oz) of water per sterilization cycle, and cost around $27K. Bertha autoclaves are
behemoths that are diffi cult to move and transport, encumber logistics, and require
high maintenance, which causes further diffi culties for the user in far-forward areas).
In contradistinction, as a modern fi eld autoclave, the PCS is low-maintenance, light-
weight (at 20 lbs achieves a 95% reduction in weight compared to Bertha), energy-
independent (a 100% reduction in electricity usage), almost waterless (uses 10 oz of
water, a 98% reduction in water consumption), and compact (at 2.1 ft
3
, a 96% reduc-
tion in volume). The compressed size of the PCS does not compromise throughput:
either 2 PCSs or 1 Bertha autoclave can sterilize 4 surgical trays in 1 hour. As a revo-
lutionary breakthrough for energy-independent sterilization, the PCS closed a critical
capability gap for far-forward Army Surgical Teams and Special Forces medical
detachments by providing an improved medical sterilization technology that is truly
portable, power-free, uses a proven sterilant, and functions at point-of-use to meet the
high-intensity, rapid-mobility demands of far-forward areas. Commercial industry is
currently undertaking development efforts under Patent License Agreements with
NSRDEC/CFD to manufacture, commercialize, and obtain FDA approval of the PCS
for military and commercial use.
Ontogeny of the PCS
The military uses chemical heaters as a convenient, lightweight technology capable
of heating rations (Meals, Ready - to - Eat — MRE) or for self - heating meals. The basic
premise requires balancing in equipoise at least two goals. One is to use exothermic
chemical reactions to react quickly and generate an intense surge of heat without
inducing explosions, and the second is to prolong the reaction such that the higher
temperature does not dissipate heat to the surroundings, but sustains thermal output
for protracted periods suffi cient to heat the intended consumable by conductive
heating. The currently used chemical heater (called the Flameless Ration Heater, FRH)
consists of the iron-activated magnesium-water chemical reaction embedded in a
polymeric support matrix and balances the goals mentioned above. The primary draw-
back of the Mg(Fe)-water reaction is the cogeneration of large quantities of fl ammable
hydrogen gas that can be hazardous when produced in the confi ned spaces of tents,
storage containers, or underwater shelters. Previous research efforts at NSRDEC/CFD
determined that scavengers of certain chemical precursors could reduce or suppress
entirely the production of hydrogen without compromising heater performance (Taub
and others 2002; Taub and Kustin 1996).
To circumvent the potential hazards associated with the FRH, select exothermic
inorganic oxidation-reduction chemical reactions have been investigated as potential
environmentally friendly (“green”) chemical heaters. These alternative heaters form
benign end-products that are safe to human health and the environment. These studies
produced one such chemical heater based on the complex oxidation-reduction reaction
