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 Quality of detectors used in monitoring? 
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Joined: Sun Aug 25, 2013 8:13 pm
Posts: 69
Location: New Mexico
I was wondering if the quality of detectors is taken into account for monitoring purposes? For instance, I have a CDV-700 with a pancake probe that is much more sensitive than, say, a GMC200. So are the readings of those using the GMC200 really worth reporting? I mean most likely they are reading far lower radiation detections than are actually happening. So we are getting huge variations in readings that don't really represent what is actually happening. I suppose it's better to have a GMC200 than nothing at all, but I am dubious about the results they actually represent. I know not everyone can afford a $1000 geiger, but an $80 unit like the GMC200 seems like a waste of time to report it's readings. Sorry if I offend anyone with that statement. But it would be nice to get an acceptably accurate reading that would either not ignore high readings, or over-report them. Might be a good idea if everyone were required to describe what geiger they are using for taking their readings in the info area of their reporting location.


Wed Oct 02, 2013 4:15 pm
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Location: Illinois
I believe the scale below is true:

GOOD = Pancake Unit Inside House (easy to damage outside)
BETTER = GMC-200 Outside
BEST = GMC-200 Outside on the filter of an air purifier 24/7



Deputy wrote:
I was wondering if the quality of detectors is taken into account for monitoring purposes? For instance, I have a CDV-700 with a pancake probe that is much more sensitive than, say, a GMC200.


Each station/geiger counter on NETC works off its own data. The problem you describe happens when one level is used for all stations. For example, Radiation Network currently uses 100 CPM as the ALERT level for any geiger counter connected to their network. NETC does not work like that.

Deputy wrote:
So are the readings of those using the GMC200 really worth reporting? I mean most likely they are reading far lower radiation detections than are actually happening. So we are getting huge variations in readings that don't really represent what is actually happening. I suppose it's better to have a GMC200 than nothing at all, but I am dubious about the results they actually represent. I know not everyone can afford a $1000 geiger, but an $80 unit like the GMC200 seems like a waste of time to report it's readings. Sorry if I offend anyone with that statement. But it would be nice to get an acceptably accurate reading that would either not ignore high readings, or over-report them. Might be a good idea if everyone were required to describe what geiger they are using for taking their readings in the info area of their reporting location.


I own many different units, some as low as $85 (GMC-200) all the way up to $3,000 (Polimaster 1703)

The pancake units I have seen have a new factory warranty of about 90-days on the GM tube. Most people who can afford one would not likely put it outside 24/7. The GMC-200 works great outside, I have had mine outside since Winter. We are looking for trends of rise & falls in the readings and the GMC-200 works great for that. When a rise (often during rain) is clearly seen, that is the time I would likely take my inspectorEXP and get a rain sample to test. Most people do say what geiger counter they are using either in their info area or have a link like me to a thread in this forum that gives many details. Even if they didn't, people should be able to look at the graph and tell by the CPM what type of GM tube is being used.

_________________
MY OUTSIDE RADIATION MONITORING STATION:
South Beloit, Illinois - GMC200 Outside on HEPA air purifier, ground level, facing West.
http://netc.com/chart/view.php?n=1%3AEB5A139C


Thu Oct 03, 2013 5:45 am
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Joined: Sun Aug 25, 2013 8:13 pm
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Location: New Mexico
KC: I would reverse the ratings for the units. :)
While the GMC200 is relatively cheap and can be more justifiably exposed to the elements, I just don't have the confidence in it to take accurate readings as I do pancake units. Granted, pancakes are more delicate and I would never permanently install one outside in the elements. Even having one inside but in an area where there isn't a lot of blocking material, I think it would be more accurate than an outside GMC200.
I do understand about how each station works off it's own data, but what if a station is using multiple geigers? I noticed this right away when I switched from the Atomic Dave unit to the CDV-700 pancake unit. Same location, same connecting cables, same time of day, but dramatically different (much higher) readings. Some of us just don't have the luxury of being able to install a geiger outside. So we are forced to use the best available indoor locations we can find.


Thu Oct 03, 2013 10:05 am
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Deputy wrote:
...some of us just don't have the luxury of being able to install a geiger outside. So we are forced to use the best available indoor locations we can find.


@Deputy - I do understand an outside unit is not always an option for everyone, I am just trying to tell people what they can do for the best detections. The reason I have it listed as "BEST" is not so much because of the geiger counter (GMC-200) obviously, but rather the fact I have it listed as outside and on an air purifier for better detection.

Any geiger counter could be used and if a pancake unit was used outside & on an air purifier... this would clearly be better than the GMC-200 outside. You do understand that just because you use a more sensitive geiger counter inside and get more CPM recorded, that does not mean your are really picking up more types of radiation. The same beta radiation that does not make it inside the house to reach the GMC-200 when inside, still will not reach the Inspector or other pancake units. With a more sensitive geiger counter in the house, you will get higher CPMs only due to the increased surface area of that unit vs. the GMC-200 unit. Well a pancake unit does detect alpha radiation where the GMC-200 does not, but again when inside the house... this is not likely alpha from outside unless your windows are open.

_________________
MY OUTSIDE RADIATION MONITORING STATION:
South Beloit, Illinois - GMC200 Outside on HEPA air purifier, ground level, facing West.
http://netc.com/chart/view.php?n=1%3AEB5A139C


Thu Oct 03, 2013 1:18 pm
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Location: Arkansas
Hi Deputy
Quote:
I noticed this right away when I switched from the Atomic Dave unit to the CDV-700 pancake unit. Same location, same connecting cables, same time of day, but dramatically different (much higher) readings


If the site has gaps in the data from your station, it will stay unreliable. The only thing Netc.com ask from you is to keep your station constant, same Geiger counter, same location. If you want to chart your data on Netc.com, we can set-up a test site just for your site. I have four test sites at Netc.com. Please help us by following this only request.
Thank you.


Thu Oct 03, 2013 1:52 pm
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Location: New Mexico
KC: Okay...I think I have it now. Thanks for the explaination. :)

Hey: I think the same problem people have with locating the geiger in the optimum location, also applies to having a unit that is in constant operation. For many folks that's just not practical/possible. For one thing, some geigers need to have the batteries changed or recharged to keep them in operation. My Atomic Dave is one like that. It doesn't recharge unless I flip a switch that swtches it from monitoring mode to recharge mode. The benefit of this is my old GMC300 NEVER finished recharging even after being left connected to a USB port overnight. The Atomic Dave recharges overnight. Probably in only about 6 hours. My CDV-700 geigers either have to be shut down to install new batteries, or shut down to recharge the batteries that are in it. So by necessity, my location will be unreliable. I also use my geigers to search for radioactive ore in my area (there is PLENTY in New Mexico), so they will go offline for that too.


Thu Oct 03, 2013 5:29 pm
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Great, that is why we design Netc.com to handle your situation of not having a constant location and Netc.com will not use your station to send out alerts either. If you never set a location on your forum profile then your geiger counter will not show up on the radiation map. The Netc.com will always be glad to have your station if the situation changes.


Thu Oct 03, 2013 8:17 pm
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@Deputy - Many of your reasons for not having a constant monitoring station (battery & needed for sampling) is why I do not uses my InspectorEXP on a station anymore. The InspectorEXP is more useful for field testing of samples after the GMC-200 has done the hard work 24/7 testing and pointed out when I need to take samples. The GMC-200 is inexpensive, durable and seems to work nice as a work horse outside in the weather. Of course I have it in a thin ziplock sandwich bag but it still endures the temps year around.

_________________
MY OUTSIDE RADIATION MONITORING STATION:
South Beloit, Illinois - GMC200 Outside on HEPA air purifier, ground level, facing West.
http://netc.com/chart/view.php?n=1%3AEB5A139C


Thu Oct 03, 2013 10:50 pm
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Joined: Sun Aug 25, 2013 8:13 pm
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Location: New Mexico
Hey: I posted my info at the correct location (I think). I put in there that it is a "temporary location" at the present time. I hope I put it in the right place!

https://www.netc.com/bb/viewtopic.php?f=13&t=390

I'm still unsure about buying and using the GMC-200. I have not had real good luck with GMC products. At least, my GMC-300E was a real loser. :(
They do have an excellent return policy, though. :)
The trick (for me) is finding a good quality geiger that doesn't cost a fortune yet gives accurate results in the location I will be using it and is compatible with NETC. My Atomic Dave certainly fits that description, except for the "doesn't cost a fortune" and I use it for other things besdies permanent monitoring.
I really don't want to use my CDV-700 units (I have four of them) for constant monitoring. At least, not without having them rebuilt/checked out first. And they are a bit large for the location I have to use them at.

KC: I'm a bit confused with your statement "the GMC-200 has done the hard work 24/7 testing and pointed out when I need to take samples". Are you talking about air samples or actual physical samples? I use my geigers for taking actual PHYSICAL samples too. :)


Fri Oct 04, 2013 11:28 am
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Deputy wrote:
KC: I'm a bit confused with your statement "the GMC-200 has done the hard work 24/7 testing and pointed out when I need to take samples". Are you talking about air samples or actual physical samples? I use my geigers for taking actual PHYSICAL samples too. :)


Yes, actual physical samples. When my GMC-200 along with the Raspberry Pi hooked to NETC records a high reading, it alerts/talks to me which I will then use my InspectorEXP if during a rain storm... a paper towel sample. This saves me the trouble of testing every rainfall sample when not needed.

_________________
MY OUTSIDE RADIATION MONITORING STATION:
South Beloit, Illinois - GMC200 Outside on HEPA air purifier, ground level, facing West.
http://netc.com/chart/view.php?n=1%3AEB5A139C


Fri Oct 04, 2013 12:39 pm
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