Radiation Survey Meter Calibrated

Radiation Survey Meter Calibrated

I mentioned a while back that I was sending my Jordan Electronics CD V-710 Model 2 radiation survey meter off for calibration. It came back very quickly from KI4U, Inc.

Useful piece of information: there was a sheet that came back that warned,

DO NOT STORE OR SHIP RADIOLOGICAL INSTRUMENTS WITH BATTERIES INSTALLED! INSTRUMENTS WITH BATTERIES INSTALLED MAY BE MIS-IDENTIFIED AS EXPLOSIVE DEVICES.

Yes, I can see that! For all of my readers who regularly ship radiation survey meters, keep that in mind!

Also, while they were able to calibrate on the X 1 and X 100 scales, it failed on the X 10 scale. In case you aren't familiar with these type of survey meters: there is a switch that lets you move through all three scales, and the dial shows a range from 0.0 to 0.5 Roentgens/hour. You multiply the scale accordingly.

On the X 1 range, it is showing just barely above 0. (A typical background exposure is 200 milliroentgens/year, which would be about .000022 Roentgens/hour. Altitude may be part of the slightly higher rate that I am seeing) If I have occasion to go up to the X 100 scale (meaning that I am measuring between 1 and 50 Roentgens/hour)--well, that's like really, really bad news, since 100 Roentgens/hour for five hours is lethal--and a combined dose of 100-200 Roentgens is going to make you very, very sick. The note from KI4U also explained:

The CD V-710 has a single calibration on the X 10 scale. All 3 scales are within the acceptable limits. The calibration potientiometer cannot be adjusted any higher, indicating that the ion chamber is becomng weak. * Did not pass on X 10.

That's not too surprising--this is a 50 year old instrument. (That it still works at all is impressive.) If I ever use this device as anything but a prop for an upcoming lecture on the Cold War, McCarthyism, and Arthur Miller's The Crucible, the X 1 and X 100 scales will be sufficient, I fear. And of course, the X 10 scale works--it's just that it is reading too low: an actual 2.96 Roentgens/hour is showing on the meter as 2.0 Roentgens/hour; multiply by about 50% to get the actual level.