Tue August 7, 2012
Sciencey Stuff

What The Heck Is A Troxler 3430 Surface Moisture Density Gauge?

That's certainly a mouthful. I’m also insanely curious, because the Denver Post is reporting that one was stolen last week.

From The Denver Post:

Health officials are warning whoever stole an engineering gauge from the back of pickup in Denver last week not to crack it open.

TheTroxler3430 Surface Moisture Density Gauge, a common piece of equipment, contains radioactive material that is safe, as long as it stays contained in the device.

Looking at the product brochure [.pdf], it’s apparent enough that it’s a nuclear density gauge. It’s commonly used to measure density and compaction for roadway construction since it is capable of measuring across a wide spectrum of materials like "asphalt, soil, aggregate or concrete and the moisture of soil or aggregate."

Here’s the sciencey part: The device uses sealed radiological sources to generate gamma rays (to measure density) or neutrons (to measure water content). The gamma source is cesium-137 and the neutron source is americium-241/beryllium, both sources are in sealed and welded containers.

Again, as long as it isn't taken apart, there isn’t a health risk. The manual [.pdf] says that there are no user serviceable parts and that the cover should only be removed by "trained service personnel."

Training is important. If you don’t have formal gauge operation training as required by the Nuclear Regulatory Commission and the USDOT, then I would hazard a guess that you are not trained service personnel.

So now you know, and knowing is half the battle. If anyone finds the device the Department of Public Health and Environment is asking [.pdf] that they call 303-877-9757.