Radium Containing Industrial Smoke Detector (1960s)

Note: This is not in the ORAU Collection but is shown for informational purposes.

Although not commonly encountered today, early smoke detectors often used Ra-226 sources. In the example shown here, the source (indicated with the red arrow) is in a chamber underneath the label. Smoke detectors for commercial use typically contained 20 to 40 uCi of Ra-226. The first radium-containing detectors for home use contained less than 0.1 uCi. Companies making these devices included Pyrotronics, US Radium Corp (Ionotron). Another brand name was the F-3 Pyr-A-Larm.