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January/February 2009
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Nuclear Gauge Calibration

ASTM Committee D18 on Soil and Rock is currently at work on a proposed new standard, WK21484, Practice for Nuclear Gauge Calibration. The proposed standard is under the jurisdiction of Subcommittee D18.08 on Special and Construction Control Tests.

Dan Pratt, senior nuclear project physicist, Troxler Electronic Laboratories Inc., and D18 member, says that two motivating factors are guiding the development of WK21484. The first was to allow the focus of D6938, Test Method for In-Place Density and Water Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth), to remain on the use of gauges, rather than their calibration. “We felt that the appendices on gauge calibration and calibration verification in D6938, while providing important information, were not really a comfortable fit in a standard that focuses on everyday use of gauges. Consequently, we felt that calibration information should be referenced in D6938 but not necessarily included in it.”

The second factor, according to Pratt, was the desire to expand on the practice of nuclear gauge calibration. “There currently exist several approaches, procedures and apparatuses for performing, verifying and checking nuclear gauge calibrations,” says Pratt. “By creating a comprehensive standard that exclusively addresses the practice of gauge calibration, we felt that the objectives, differences and similarities, as well as possibilities and limitations of these different approaches could be adequately expressed.” Pratt also hopes that work on the proposed standard will open up dialogue on different calibration approaches and what can be accomplished by them.

“From a practical perspective, the gauge user should be able to read the proposed standard once it has been approved and decide which calibration or verification approach would be best for their device,” says Pratt. “The organization that is using the proposed standard to perform the calibration or verification, in turn, should be able to read the standard and design their calibration or verification procedure to meet the specific need of the gauge user.”

Pratt says that the task group working on WK21484 welcomes participation in the ongoing development process.

CONTACT

Technical Information: Dan Pratt, Troxler Electronic Laboratories Inc., Durham, N.C.

Phone: 919-314-2707

ASTM Staff: Robert Morgan

Phone: 610-832-9732