CONTACT: Ternel Martinez, [email protected], 505-665-7778
LOS ALAMOS, N.M., Dec. 2, 1998 -- Researchers at the Department of Energy's Los Alamos National Laboratory have developed a trio of sampling tools capable of extracting liquid, gas or powder samples from
sealed containers and permanently sealing the point of entry -- all within a matter of seconds and without exposing people to the contents inside.
Although the researchers developed the tools for nonproliferation and counterterrorism purposes, personnel also can use the tools to quickly and safely verify contents at storage and industrial sites; perform quality-control checks on chemicals before they are used; and check the unknown contents of abandoned or poorly marked containers.
"The really nice thing about these sampling tools is their ease of use under less than ideal conditions," said Roger Johnston of Los Alamos' Advanced Chemical Diagnostics and Instrumentation Group. "The tools are very low-tech, and they're incredibly light and can be taken virtually anywhere where sampling needs to be done."
The tools may one day completely replace expensive, cumbersome sampling devices currently used, many of which require opening the container or its bung (access port) and using a tube or scoop to transfer the sample to a storage bottle. The new tools can obtain samples anywhere along a container's wall at thicknesses up to one- half inch and internal container pressures up to eight atmospheres. All one needs to use the new sampling tools are a standard, off-the- shelf electric drill and about two minutes of training.
Johnston and fellow researchers Anthony Garcia, Ron Martinez and Eric Baca, also from the same group, began working on the sampling tools about three years ago on behalf of the U.S. military, which was seeking an easier way to sample containers for possible chemical, nuclear or biological materials with minimal risk to personnel. The first prototype took more than a year to develop. Since then, an additional two models have been developed.
Model A can drill, sample and reseal in a single step and can be reused on different containers. Models B1 and B2 remain attached to the container wall, allowing researchers to take multiple samples from the same container without having to redrill. The B1 and B2 models also serve as attachments for plumbing, valves or other instruments.
Model A works as follows: the sampling tool attaches to the tip of the drill. The user places the tool's exterior silicone rubber sheet against the container wall and drills, with the rubber sheet acting as a sealant. Once the tool penetrates the container, the drill bit immediately retracts, puncturing the septum at the top of a Vacutainer tube --- the same kind used in hospitals to obtain blood samples -- located inside the tool. The Vacutainer then pulls in a sample through a side fill hole in the hollow drill bit assembly.
Once the tube is full, the drill's continued rotation pushes a piston forward, pressurizing a compartment containing a flowable sealant, which seals up the hole. The sealant fully cures in 24 hours. Model A can be used multiple times.
Model B1 uses a hollow, stainless-steel, self-tapping screw to drill holes up to 4.7 millimeters large and tap the container wall. During this process, a silicone rubber septum presses against the wall and screw, sealing the area to prevent content leakage. The septum also serves to capture the potentially contaminated kerf (metal shavings) generated during the drilling and tapping process.
Once the tool reaches maximum penetration, the force created by the compression of the exterior septum against the container wall causes the drill to stall. At this point, the user stops drilling and releases the drill chuck, leaving the sampling tool in place. The tool's good mechanical seal allows people to obtain samples from containers with internal pressures up to eight atmospheres.
Model B2 has additional features that allow the tool to hold more kerf and cut more quickly through hardened metals and container walls up to 13 millimeters thick. This model uses a fluted commercial drill and tap, or a drap, to drill through and tap the container. A rubber bulb called a "chipmunk" located at the front of the tool captures the kerf
and moves it out of the way; the chipmunk also serves to prevent content leakage during the drilling and tapping process. Once the process is complete, the chipmunk is fully compressed against the container. An O-ring inside the chipmunk makes the final seal against the container wall.
To obtain samples from either model B1 or B2, the user employs a double-needled sampler containing a Vacutainer inside. The needle punctures both the sampling tool and Vacutainer simultaneously. For model B1, the Vacutainer obtains its sample through the self-tapping screw's side fill hole; for model B2, suction causes the sample to travel along the drap's flutes into the Vacutainer's housing.
Johnston said the costs of making models B1 and B2 in large quantities are estimated at $4 and $17 each, respectively. Because model A is by far the most complex tool in terms of its internal moving components, its manufacturing cost is estimated at about $650 each.
"These sampling tools are great because they're fully portable, easy to use and can be used on virtually any type or size of containers, not just 55-gallon drums," said Johnston. He added that, in addition to the military, personnel from the Waste Isolation Pilot Plant in Carlsbad also are considering using some of the sampling tools.
Additional potential applications for the sampling tools include allowing users to transfer liquids between containers; monitor the condition of materials in storage; or obtain archive samples of materials before they are incinerated. Emergency-response, law- enforcement and governmental personnel also may use the sampling tools to discover drugs during customs inspections or during raids on suspected illegal drug-production facilities. The tools also may be useful in environmental enforcement raids and in investigating the contents of sealed containers found at fires or other disaster scenes.
Johnston said his team currently is working on a new generation of sampling tools for future uses. For example, he said, his team is miniaturizing models B1 and B2 even further and creating cosmetic covering for model A's seal plug for undercover sampling. Also, by incorporating special speciation paper into the Vacutainers or by combining the tools with Los Alamos-developed acoustic interferometry, which identifies chemicals by way of acoustic resonance spectroscopy, users may be able to instantly identify chemical agents on the field. The researchers currently are seeking patent protection for all three tools.
Los Alamos National Laboratory is operated by the University of California for the U.S. Department of Energy.
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NOTE TO JOURNALISTS: A sampling tool demonstration videotape is available upon request.
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