Radioactive Gauges

1950 - 1952, M38, questions, discussions, regarding anything related to the M38.
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Buster1
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Radioactive Gauges

Post by Buster1 » Sun Feb 20, 2022 2:00 pm

I’ve read everything I can find here and on the web, but it’s not clear to me if the M38 gauges are radioactive.

Does anyone know when they stopped building gauges with radium? A speedo repair guy I talked to said something about the late 40s, as he wouldn’t deal with my speedo if it was from the 40s.

I have an original fuel gauge too, but not certain if it’s safe to open up.

Thanks!
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Re: Radioactive Gauges

Post by Manic Mechanic » Sun Feb 20, 2022 2:13 pm

i don't know about the gauges but radium was used on watch dails to make them glow until the 60s i think

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Re: Radioactive Gauges

Post by Ron D » Sun Feb 20, 2022 2:46 pm

Geiger Counter would tell for sure. Anything else might be guessing.
I read somewhere that your local fire station might have one (for hazmat testing) and might be willing to help a tax-paying citizen in exchange for donuts.

Good luck!
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Re: Radioactive Gauges

Post by YLG80 » Sun Feb 20, 2022 10:34 pm

If not sure, measure.:wink:
Look for GQ GMC-320 Plus Geiger Counter on your giant online store. :mrgreen:
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Re: Radioactive Gauges

Post by dpcd67 » Mon Feb 21, 2022 5:55 am

I wore an Issue wristwatch with radium hands for most of my career, until cell phones were invented and I stopped wearing a watch.
It is here somewhere.....it stopped working anyway, but the hands still glow in the dark.
Yes, M38 gauges used radium. It was considered harmless back then. Until at least 1960. Even though it no longer glows in the dark, the radium is still radioactive.
Read this: the NRC takes this seriously.
I also read an article about a Canadian collector taking an MV across the border; set off rad detectors.
A guy I know took some scrap metal to the yard; he had some M series gauges in the load. His truck set off the rad detector at the gate and they told him to turn around and leave.
(None of this I worry about; just for info, and for the record; I know zero about this topic; just what I read on the internet. And the one guy at the scrap yard). Your thoughts may vary.
And there is a thread on this on the MB page here.
https://www.nrc.gov/docs/ML1627/ML16277A257.pdf
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Re: Radioactive Gauges

Post by Buster1 » Mon Feb 21, 2022 4:06 pm

Thanks guys, and thanks again dpcd67. I appreciate the info and the documents.

I spoke to Abbott Instrument (who is working on my speedo) and they are aware of the radium paint and issues, but were uncertain what years of dials and gauges on our old Jeeps would be affected. They take precautions as well, but generally are not concerned unless doing work where they physically touch the face of the gauge or needle, or are scraping stuff off the face and intend to repaint letters, numbers, or a needle.

Interesting stuff.
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Re: Radioactive Gauges

Post by Von Loon » Tue Feb 22, 2022 3:19 am

Would be interesting if someone has access to a radioactive counter device and find out actually how much or what level of radioactivity there really is in a M series gauge.
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Re: Radioactive Gauges

Post by dpcd67 » Tue Feb 22, 2022 7:31 am

First post I see; welcome.
Since you are new, you are tasked to find a Geiger counter, and measure a gauge, and report back to us on the findings. There are plenty of them on eBay.
The new guy gets the dirty jobs.
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Re: Radioactive Gauges

Post by Buster1 » Tue Feb 22, 2022 4:31 pm

Well I had my fuel gauge tested today. Presumed original 1951.

It’s radioactive ☢️

The FD chief checked it with his machine. Background radiation in the room was 60-70 CPM (counts per minute). My little fuel gauge was measuring 1600 thru the glass, and much lower on the back of the gauge, I think it was 200-300.

He was not concerned, and said that those numbers are fairly low. He said granite countertops and smoke detectors will have 1000-1500 CPM on average. But I guess I’m still wondering about it. He said put it in the Jeep if I want, enjoy it, but maybe not mess with it or open it. Crazy stuff.

BTW, a gallon of ice cream donation to your local FD goes a LONG way!
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Re: Radioactive Gauges

Post by Bill H. » Tue Feb 22, 2022 8:10 pm

I used glow in the dark powder from the hobby store and mixed a little with clear fingernail polish then painted the needle and tics on WWII speedometers. They looked really good and actually glowed bright enough to see clearly.
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Re: Radioactive Gauges

Post by YLG80 » Tue Feb 22, 2022 11:37 pm

Buster1 wrote:
Tue Feb 22, 2022 4:31 pm
Well I had my fuel gauge tested today. Presumed original 1951.

It’s radioactive ☢️

The FD chief checked it with his machine.
Your FD chief is a reasonable person… and he did first measured the background radiation. That is good.

You have to consider first the integral/integrated dose.
This is for example the cumulated dose that killed women painting the gauge needles and face plates during the production.
This is because they have absorbed a very high integrated dose along their professional life.(similar issue in the gas industry with the tetraethyl lead killing the workers)

Afterwards, when that gauge industry has started to measure the number of workers being ill and dying from radiations, the numbers were used to calculate the maximum integral dose that a body can support.
First symptom was a tongue cancer because the women were putting their brush between their lips to point their brush or even use their tongue to reshape their brush full of radium.

Same method was used with the doctors and the XRays to calculate the maximum integrated dose.
Same method was used with people irradiated by bombings or nuke accidents like the Windscale (UK) and later TMI (US) accidents which were key to start defining the max. integral doses.

You are obviously not in the situation, so no worry as the FD chief said.
You have to be cautious when you open the gauge and start working on it: do not ingest or inhale radium particules.That’s it.
Do not worry you do not need to wear a dosimeter when driving your jeep. :wink:
Yves (nuke engineer)
Last edited by YLG80 on Wed Feb 23, 2022 12:54 pm, edited 1 time in total.
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Re: Radioactive Gauges

Post by dpcd67 » Wed Feb 23, 2022 9:58 am

Yves; Nuke Engineer; that explains a lot!
(And I mean that in a good way.)
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Facts and figures - speedometer radioactivity level

Post by YLG80 » Tue Mar 29, 2022 2:55 am

Facts and figures : Here is a measurement of my jeep King-Seeley speedometer radioactivity :mrgreen:

https://youtu.be/89u0tCNdfg8

No doubt, there is radium Ra-226 inside !
Be aware that the cosmic radiation is almost 4 times higher in the ISS space station with about 10 µSv/h !
But do not sleep with your speedometer on your pillow ! (µSv/h = micro Sievert per hour)

The ambient radioactivity here at home and around is about 0,12 to 0,15 µSv/h or 120 to 150 nano Sievert. This is normal.
Cool no Cesium Cs-137 remains from Tchernobyl. (Half life 30 years)

Yves

Measurement in CPM in the post above are much higher :shock: .
If a CPM = 0.0057 µSv/h that means 9,2 µSv/h radiated by that fuel gauge which is comparable to what they receive in the ISS.
Not yet dangerous but much higher than my KS Speedometer.
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Re: Radioactive Gauges

Post by JMZ421 » Tue Mar 29, 2022 10:01 am

For every inch you move that device away from the gauges the CPM's go down substantially. I do not want to sound too stupid but based on your calculation how long would someone have to be seated in front of the gauges(your right knee, specifically) for there to be any danger to your body? I would think that is the basic question to be answered. The concern should be opening up those gauges to repair which has been discussed often. Really appreciate your input as this is very interesting.
Thanks, John

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Re: Radioactive Gauges

Post by 70th Division » Tue Mar 29, 2022 5:42 pm

Buster1 wrote:
Sun Feb 20, 2022 2:00 pm
I’ve read everything I can find here and on the web, but it’s not clear to me if the M38 gauges are radioactive.

Does anyone know when they stopped building gauges with radium? A speedo repair guy I talked to said something about the late 40s, as he wouldn’t deal with my speedo if it was from the 40s.

I have an original fuel gauge too, but not certain if it’s safe to open up.

Thanks!

Hello Buster,

A great post !

On my M38A1 every gauge is radioactive,
On your jeep I think they are all radioactive as well, as all M series vehicles.

On the WW2 Jeeps, only the speedometer is radioactive.

I have a VDO German made speedometer , postwar, in a French MB return jeep, it too is radioactive.

I have opted to replace the old speedo as I restore my GPW jeep, with Joe's Motor Pool speedometer.
The main danger would be inhaling the paint dust from bench work on a speedo, or gauge.

The paint dust is radioactive.

Personally I would avoid it, and replace them.

Many do repair them but just be extra careful, and contain any debris, etc.


Best Regards,
Ray


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