We can use three instruments to measure radiation *
READ ME FIRST: If you want to buy a radiation meter and use it to measure for example uranium rocks, DON'T BUY A CD V-715 (or CD V-717, CD V-720). They are used to measure only very high radiation and the needle won't move a bit in normal conditions. Only the CD V-700 is used from the Civil Defense equipment to measure low radiation, like uranium rocks, natural radiation, smoke detectors etc (except the CD V-700, you can use also CD V-457, CD V-757 and CD V-718, but they are all rare and expensive). Many of the EBAY sellers describe the CD V-715 as a geiger counter for hot rocks, but that's not true. If you would see a movement on the scale, you would be dead :-). Many people buy those CD V-715's to check their collection of uranium rocks, and they think that the rocks are not radioactive. Of course they are (not all), but you won't see it on a CD V-715. It's the same for all other models, buy only radiation meters that have a scale in mR/hr (milliroentgens), if you have a meter in R/hr (roentgens), you won't find a source strong enough to show a reading on that meter. But if you want to have a radiation meter for a war or accident, the you need a CD V-715. Because the CD V-700 can be used in low radiation fields, but if the radiation is higher than the scale it can show a false zero reading (but as I said, it would be only in a war, terrorist attack, power plant accident etc.). In this case, the CD V-715's are used.
On this site, I am describing mainly the Civil Defense radiation meters, which were produced in the 60's. Today, nearly all meters are digital, they are more accurate than the CD meters and they have also a wider range, so there is no need to own the survey meter, geiger counter or dosimeter, the new meters combine all these meters into one unit. But also, the CD meters are much cheaper. I am collecting these radiation meters and this site is a guide for others, describing the entire CD program. These radiation meters are mostly not suitable for professional use, but rather for collecting, preparing for a nuclear disaster, checking radioactive rocks or just playing around.
SURVEY METER : This meter shows radiation usually in R/hr. R is an abbreviation for Roentgen and R/hr is an abbreviation for Roentgen per hour. A survey meter show the actual intensity of radiation. It's like a speedometer on a car. That means ,if the survey meter shows 50 R/hr and if you stay on that place for two hours, you will get 100 R. Survey meters are for measuring of high radiation. They have usually a Ion Chamber to measure the high radiation.
A sample of a scale on a survey meter. You can multiply this scale x0.1, x10, x100.(model CD V-715).
A view on the CD V-715
CD V-715 Civil Defense High-Range Survey Meter 0-500 R/hr range
It's weight is 3.25 pounds. Die cast aluminum and drawn steel case. It's watertight and will float. Powered with one D-sized battery, continuously for 150 hours. Instruments accuracy is +- 20%, in temperature from -20F to 125 F.
You can buy this survey
meter at www.radmeters4u.com
. The price depends on that , if you want a tested and calibrated,
then it costs 275 $, and if you want an untested, not calibrated, then
it costs 40 $. .You can buy this radmeter on auctions cheaper, but you
will don't know, if it will work. You should calibrate this radmeter
every 4 years (in a calibration service)
More about the CD V-715 here
see Civil Defense section
DOSIMETER : A dosimeter shows the total accumulated amount of radiation to which you were exposed. That means, if you were on a place which has a radiation of 50 R/hr and you were there two hours, you will see at the dosimeter 100 R (it's like a odometer of a car). A dosimeter can be in a form of a pen. You need a dosimeter charger for it, if you want to reset it to 0 R/hr." However today's dosimeters work on a digital principle, they don't need to be charged and they show the reading on a display.
A sample of a dosimeter scale. (It shows the reading, if you look through it).
A view on the dosimeter CD V-742
|CD V-742 Dosimeters and CD V-750/756 Dosimeter Charger|
These dosimeters show the total accumulated amount of radiation to which you were exposed. They are high-range radmeters. You will need a dosimeter charger to get the reading back to zero. . You cannot change the scale of a dosimeter.
can buy this dosimeter at www.radmeters4u.com
. The price depends: If you want it tested, one will cost $45. Untested,
you can get 3 dosimeters for $60. The dosimeter charger costs $65. The
charger need a battery. There is a charger with a piezo-electric system:
The CD V-756. This one doesn't use batteries, but is rare and hard to
More about the CD Dosimeters here
see Civil Defense section
GEIGER COUNTER: These meters are intended for fine measuring. Their scale is usually in mR/hr. mR is milliroentgen (1 R = 1000 mR). They have a Geiger-Muller tube instead of an Ion Chamber.
The best known geiger counter from the Civil Defense equipment is the CD V-700
|CD V-700 Geiger Counter|
Information is from the
Civil Defense section
You can buy calibrated CD V-700's at www.premieritems.com for 149$ and not calibrated units for 59$.
More about the CD V-700 here.
More information about radmeters is in the civil defense page.
* these are the main types