Technical Assessment of the Man-in-Simulant Test Program (1997) / Chapter Skim
Currently Skimming:
4 Test Methods and Sampler Selection
4 Test Methods and Sampler Selection
Pages 37-48
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 37... ...
Estimates of possible battlefielct concentrations of chemical agent, the BRHA (bocly region hazard analysis) , estimates of the cutaneous toxicity of agents, and personal factors, such as heat loacling, may ultimately provide a rational basis for determining the relative acceptability of chemical protective ensembles.
|
From page 38... ...
. Direct measurements of absorbect close would require biological monitoring (i.e., drawing bloocl specimens, collecting urine, saliva, or breath samples, or taking tissue samples for analysis)
|
From page 39... ...
Relatively small exchanges, if repeated often enough, can rapidly equilibrate concentrations inside and outside a garment. Bulky samplers under the garment couIcI stretch neck, wrist, or ankle openings and degrade suit performance.
|
From page 40... ...
Supplying air with a fairly constant concentration of simulant over an extended period of time, in the absence of a mechanism for removing or absorbing significant amounts of the simulant, would tend to create a uniform concentration in all parts of the chamber. Maintaining uniform concentrations in animal exposure chambers, however, has proved to be a problem in toxicology experiments (Smith and Fowler, 1985~.
|
From page 41... ...
This allows for comparisons of simulant concentrations at specific locations arounct the suit (e.g., elbow, knee, etc.) OPTIONS FOR IN-SUIT MONITORING This section outlines three major approaches that might be used to determine the amount of simulant inside a protective ensemble.
|
From page 42... ...
The effect of humidity on active samplers would probably be greater than on passive samplers with nonporous membranes. External Pumps and Tubes A system with pumps, connecting tubes, and samplers on the outside of a suit, with tubes passing through openings into the suit, has the advantage of permitting the use of bulkier equipment with better control over flow rates, sorbent beet volume, anct operating temperature of the sorbent becl.
|
From page 43... ...
Straps may alter the results in a number of ways: they couict decrease the normal flow of air between body regions by constricting the space between suit anct skin; they couict alter permeation qualities by compressing the suit material; they couicl decrease the area exposed directly to simulant concentrations anct thereby decrease the in-suit concentration; anct they couict increase sweat absorption by hoisting the suit next to the skin, which couict alter suit permeability. Finally, an active sampling system ctraws make-up air from outside the suit into the suit, which would necessarily increase the amount of simulant beneath the shell.
|
From page 44... ...
Several pumps could be carried within the weight limits of a fielct pack, but then exercise protocols that do not require use of the fielct pack would be severely limited. The bulk of external portable samplers would be less problematic than the weight but might create problems if exercise protocols required crawling.
|
From page 45... ...
The dosimeters or monitors use Brownian motion to control the sampling process, enabling lightweight, low-cost personal monitors that do not require a power source. They rely on a concentration gradient across a static or placid layer of air or other medium to induce a mass transfer.
|
From page 46... ...
A commercial passive sampler (DuPont PRO-TEK ~ exhibits a markoct decrease in sampling rate below a laminar flow velocity of 1,000 cm/min (0.17 m/s)
|
From page 47... ...
Although this exceeds the ctimensional requirement, interposing a barrier membrane in proximity to the adsorbent with a minimal diffusion path would solve the problem. Natick Sampler The Natick sampler is a type of passive sampler clevelopect at the Natick RDEC specifically to cletect MeS vapor for the MIST.
|
From page 48... ...
These findings react to the obvious conclusion that the permeability properties of skin and polyethylene are clifferent, especially for a nonporous lipophilic membrane like polyethylene, which does not reaclily transmit water to the sorbent layer. The committee askoct whether the same basic clesign would work with a different simulant.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.