Radon detector for under $100.00

[Richard Hull]

Will radon diffuse through plastic??? That is a massive atom, even if it is monatomic.

The alpha only probe that Frank talks about usually uses a thin plastic mylar aluminized membrane that the alphas can penetrate. On the inside of the probe handle is a 1" PMT staring down on the inside of this large area membrane which is covered with ZnS. These probes are extremely good at alpha detection. These probes, alone, usually cost nearly $1000.00 new

Of course, in a $100.00 radon detector this is not the case. As I have not observed the inards in great detail, I can't speak with absolute authority. However, I am relatively sure this is a simple air breather ion chamber looking at an FET input probe. It is the only scheme that is inline with the price.

Richard Hull

[Frank Sanns]

A half dozen interuptions and phone calls and click to post rather than loose the thought ended up being incomplete. Yes I agree that the electronic radon detector uses an ion chamber/MOSFET electrometer setup for alpha only detection. It will not pickup gamma. Try and you will be surprised how selective this cheap unit is. I have one and found my house to be at the 40 pCi/l range on the worst of days. There were other periods where the readings were as low as 2. Apparently low pressure weather system and rain are being reported as elevating interior radon. I don't know that I observed ANY correlation with any particuar phenomenon but the radon levels did vary over some kind of range.

Yes, diffusion is possible through polymers. There are a few ways that radon will go through a polymer. It can effuse through an open pore polymer or open cell foam. The pores can be small enough to not let the finest particulate through but still pass radon. Polymers can either be very symetrical and pack well or they can be very unsymetrical and have large side chains or atoms that prevent close packing. The intersticies of a polymers can be fairly cavernous as atomic sizes go. Also, copolymers (consisting of 2 seperate polymers) can have one polymer disolved out after it is formed to give internal paths for gasses to follow. Other additives, especially carbon blacks, can be added that provide a path through the polymer. The carbon particles provide an interface void at the polymer interface and makes an open albeit small channel for gasses to pass. It is well known in the industry that if you want a good vapor barrier, you don't make it black and you don't have voids it in of any kind.

Frank S.

[richnormand]

Here is an update.

After the reading done in my air tight sample box (see previous post):

I installed the detector again on top of the exact same sources, but in the open air instead of in a sealed box. After the initial startup calibration “ – “ reading it started at 3 then dropped back to 1 (normal reading where I live) in a matter of three days. So at first glance, it does look like the previous high reading was due to radon building up in the box and it also looks like the detector is immune to a fairly high background.

I will now reset and redo the startup cal away from the sources and then repeat this setup exactly. Any difference of behavior would then be due to that initial cal.

[dbitton]

I bought this one in e-bay for $100 plus delivery. After I installed it in a little room (cave) in the basement of an apartment block, it started to read 2.5 pCi/liter steady for one week, BUT, when I moved to another "cave" close by, it started to read 4.1 and now after 10 days it reads 4.7 pCi/liter . Should I panic?, I read most of the reports "againts" EPA recomendations and found them very particylary interesting and "iluminating".
We are already planning to install some kind of extraction or circulating fan/duct to reach that "cave", even if that area is not accesible for most of the resident, except when I need to store my "surpluss" equipmetn and tools.
regards from downunder
Daniel
Richard Hull wrote:
> Some of you may already have seen these somewhere, but I just purchased from.....
>
> http://www.radonease.com/
>
> .....a really slick little radon detector. As most of you know, I have a small collection of U ore minerals in my mineral collection. I was concerned about accumulating radon in my upstairs lab as some of my specimens that are in the open are quite hot. As we all know, radon oozes out of U rock at a rather constant rate over a period of billions of years.
>
> As many of you also know, I have an $8000.00 Pylon radon test kit with three lucas cells and all the electronics to test radon levels to a high level of precision. The kit requires about 1 hour to set up and take a sample. It also requires a 20 hour sampling period with a new scintillator reading automatically taken and recorded every 10 minutes from the lucus cell with the trapped air sample in it. All this is recorded on a printer and after 20 hours, averages are taken and equations solved, manually, to determine the actual room level in pCi/liter. All of this warrants a very high degree of precision with very little error.
>
> This swift little detector that I just purchased uses a special internal ion chamber and, after 7 days of total stupidity, it finally throws up your room's radon level to within +/-20% in pCi/liter on a nice, continuously lit, 3 digit LED display. After two weeks, I am most pleased with its performance. Once it finally does readout, (~3-7 days of sampling) it will do a continous daily update to your continuous average level in "long term" mode.
>
> I have mine set to "short term" mode and once it starts to read, the average is updated hourly until the seventh day when it erases all past data but keeps the current reading and starts another hourly updated seven day cycle.
>
> This thing has a micorprocessor in it with several modes and features plus, a small manual comes with it. Woe betide the idiot who unplugs it as it starts all over again on the 3-7 day dummy cycle reading two dashes "--". You will want this on an unswitched outlet where kids and other family dunderheads will not disturb it. You can forget instant gratification with this thing. It comes with the customary "wall wart" and a generous 10 feet of wire on it for locating it anywhere.
>
> If you are looking at a living space with constant comings and goings the long term mode is best. If you are looking at a non-living area where there is little traffic you might want to use the short term mode as it picks up short term increases better.
>
> The readout is rounded to the nearest whole digit, BACKWARDS!
>
> 1.1 or 1.9pCi/liter is readout as "1" There are no decimals, obviously, in a $100.00 instrument of this type. It sounds an alarm of four loud beeps every hour if you are over the government acceptable, continuous living limit of 4 pCi/liter.
>
> My unit, after two weeks, reads "1", so, I am most happy.
>
> I spent the time over the weekend and arrived at 1.73pCi/l with my professional setup and so the little box is doing OK and so is my lab space.
>
> I attach an image of the device in my upstairs lab. I have it on a wall near my minerals. Pretty cool for a bit of piece of mind.
>
> Good news for all you folks with 159pCi/l basements. You can breathe a radioactive sigh of relief..... The alarm on this puppy can be turned off in the menu mode!
>
> Richard Hull

[Richard Hull]

Radon at 4 pCi/L is not bad provided the "little cave" is isolated and you are not there for protracted periods. I would not worry about it.

Richard Hull

[dbitton]

Thanks Richard for the info/assurance. Now is reading 5.1pCi/L.
This unit is the Siren-pro III and looks that it is working ok.
I am trying to repair a G M tube I broke the mica window.
I read ALL the notes from the forums, and they are very helpfull.Tomorrow I am going to the Library to see if I can borrow the "Electron and nuclear counters: Theory and use" book from Korff, as you already recomended. If I succeed doing the refilling, I'll post the proccess and pics. By the way, how you measure the quantity of methanol (as in a gaseous state?).
For the Argon, I have a "full" vacuum pump + vac chamber with some piping for refilling and a good digital vac gauge. I will pull full vac and later release the Argon (slowly) to read 50 torr(absolute), I am in the right track?
What I can do to quantify the methanol mixture?
Hope to hear from you . Regards from downunder
Daniel
Richard Hull wrote:
> Radon at 4 pCi/L is not bad provided the "little cave" is isolated and you are not there for protracted periods. I would not worry about it.
>
> Richard Hull

[Richard Hull]

Repairing a GM tube is no mean feat! Good luck.

You do not have the critical Bromine needed to make a halogen quenched unit. You plan to use alcohol (ethyl), I assume?

The alcohol will vaporize immediately at low pressures.

Korff and Knoll recommend about 20cm or pressure in a final alcohol quenched tube in a 90:10 argon/alcohol mix.

You will need two inlets to the tube with stopcocks on each one with argon in one and the other with alcohol.

Evacuate to well below 1 micron. Back fill first with alcohol to a pressure of 20 torr and then open the argon until you read 200 torr. Supposedly this tube will require a lot more voltage (1200-1400 volts to work. The absolute count lifetime limit on this tube will be 10e9 counts, but it will start acting flaking with a shortening plateau after about 10 million counts. A halogen quenched tube is, effectively, an infinite count lifespan device.

Knoll is a more modern author on GM tubes (Radiation Detection and Measurement). Your library is more likely to have Knoll's book, but Korff's book gives more complete and detailed construction data.

Richard Hull

[richnormand]

To complete my original experiment report with the radon detector.

After my initial tests as previously reported I tried to be a bit more systematic about the procedure.

After the normal initialization (with the – on the display) I waited three days for the reading to stabilize at 1 on the readout. This is my normal reading in the basement so far.

I then placed my radioactive samples under the meter and waited another three days. No change. It would appear the even though the unit is cheap it has an excellent background gamma rejection ratio!

Then I placed the whole lot (keeping the same geometry in the cardboard box) in my sealed sample box. Within the same day the reading started to rise. After four days it was reading over 50 and still going up! This must then be due to actual radon building up in the box and not background radiation. Looks like Richard’s comment in his previous post are accurate.

Took the detector out again.

It then took another three days for the detector to get down to a reading of 4. It is still slowly going down and may take more than a week to get back to its normal reading. Most likely due to long lived daughter products as mentioned by Richard.


Pretty good for a simple $100 unit!

[Richard Hull]

I don't have any kids, but consider the radon daughters to be my own. They represent a very fortuitous opportunity to experiment with short lived isotopes. The down side is the final long lived daughters which are not effectively detectable, but real nonetheless.

If one reads Rutherford's biography and other accounts of the Cavendish during the fecund period 1900-1930 there is always a humourous tale of this or that clumsy person accidentally breaking a radon ampoule and trashing 20 on-going, different experiments throughout the building. Rutherford, himself, was the culprit on more than one occassion.

Radon was the #1 safe, portable, radiation source during the early days and the radium sources were always kept and "milked" in another building under careful supervision, due mostly to the cost of radium and the need for absolute fastidiousness in handling and transferring the ampoules about the real laboratory area. Radon ampoules were often blown hyper-thin by the on-site, research laboratory's glass blower so that alpha particles from the radon could be used actually coming through the ampoule!

The radon radiation load in these was often so intense that within days they would turn brown and older ones would be opaque! Easily in the range of ten trillion pCi/l (stp).......Imagine that gas load in the air of the Cavendish with Hans Geiger down the hall trying to visually count Scintillations for 8 hours a night! Geiger was constantly pissing and moaning about the highly variable background spoiling his work. Geiger's wriggling about this used to amuse Rutherford.

Geiger was so presicely Germanic and Rutherford was so laid back New Zealandic.

Richard Hull

[Tom Dressel]

Well, I received my series III radon detector on Saturday. I set it up in the basement in a storeroom under the stairs. This afternoon after ~48 houres it was reading 38.5 pCi/l !
I cleared the memory and started another run in the living room one floor up.
I am somewhat worried about the high levels in the basement.

Tom Dressel

[Jon Rosenstiel]

I've had my series III for almost two weeks now, about ready to whip up a report on my radon levels here.

One thing I did note, the initial reading was fairly high, then steadily dropped as the days ticked by. (Though my initial reading was only1.9 pCu/l, not the 38.5 you got)!

Jon Rosenstiel

[richnormand]

If you read my previous posting you will see I put my series II through hell in my sample box. May I suggest you put your unit several days in a well-ventilated area and see if it goes down to a 0 or 1 reading. This will ensure it is actually working properly and not contaminated.

Only then, I would bring it down back to the basement. If the high reading persists then count yourself lucky to have found it at this time and be able to take remedial action.

[Richard Hull]

Wow, Tom! That is a gang o' radon for a basement living space. I though only folks in Pittsburgh had those levels!

Actually, I found about 40 homes in and around Richmond with those levels on the Radoneaze website.

http://www.radonease.com/

Most are in south Richmond on the edge of the Amelia pegmatite dykes, (thoron, Ra220).

Pittsburgh had basements in the thousand pCi/l range!

Still, I would not want to spend more than a few hours/week in a 40 pCi/liter basement.

The 4pCi/l federal safe point is for a 24-7 dwelling and living level. The gas is heavy and in a calm basement it probably won't invade the upstairs. I would only be concerned if a wipe test yielded obvious levels of depositied daughters.

Setup a GM counter (must be mica windowed) outside or in a very low background area. take a 10 minute background reading using a physical counter not a meter.

Take a normal paper towel and fold it over 4 times so you have about a 4X4 wipe. Wet it and take it into the basement and wipe a low lying long straight stretch of something. (floor, table rung, etc.

Place this quickly under the GM counter less than 1cm from the mica window and reset the count. Measure for 10 minutes and compare to previous background. This is a crude, qualitative, no long term wait, test for significant radon levels.

Doing this wipe in many homes on the face of an old analog TV that has been on for >1hour continuously will often shock folks.

The TV test is NOT an indicator for high radon levels as it is electrostatically attractive over large volumes of atmosphere. Only the quiet area wipe test is good.

Richard Hull

[Tom Dressel]

I got a 48 hr radon level of 7.2 pCi/ liter in the living room today. Then I realized that the shelf that the detector was sitting on was really dusty. So I dusted it off and started a new run.

I did a qualative vesion of the mica window GM count test suggested by Richard (I had no problem finding lots of dust to pick up in the house) and there was qualatively at least a 2X increase in the counts when exposed to the dust.

Tom Dressel

[Richard Hull]

2X on a broad dust wipe is not too bad in my qualitative estimate. I have wiped in my lab and had 2X off a low corner bench shelf. My main attached lab radon level is about 2-3 pCi/l (concrete floor) while my upstairs indoor dwelling lab level is 1-2 pCi/l. I try and make all quantitative radon measurements at about belly level with my pylon lucas cell instrument. Floor level could give some overly high levels and levels taken above the head level would be low most of the time.

Richard Hull

[Jon Rosenstiel]

I've had my Series3 sitting on a buffet in my living room for just over two weeks. It's initial reading was 1.9 pCi/l, but it has steadily dropped and now after two weeks has leveled off at 1.1 ~ 1.2 pCi/l.

I reset it and moved it to a 14' x 14' storage shed where I keep my small supply of radioactives (and lots of other junk). I'll post another update in a couple of weeks.

Jon Rosenstiel

[Tom Dressel]

As of this writing I am having a sub slab suction system installed in my house to reduce the Radon levels. It consists of a 3" hole in the basement floor with ~5 gallons of dirt removed below the slab. The cavity is evacuated to the out side via a 3" PVC pipe and a fan. The goal is to establish a 2" water vacuum under the slab to prevent Radon infiltration into the basement.

Tom Dressel

[Richard Hull]

I bet that ain't cheap! Good luck on your remediation efforts. In some special, sad cases, remediation can cost tens of thousands. You can't move away from the problem, for you cannot willingly sell a radon ridden dwelling without informing prospect ive buyers. Some folks who consider themeslves "there for life" will just either live with the problem by reducing time in the basement or seal the basement off from the upstairs.

Just out of curiousity, Tom, How long have you lived there and been suckin' down th' basement rads? Do you spend a lot of time in your basement? Often, it is the only place in the house that a hobbyist/amateur scientist has that his Mom/Wife will let them have.

Richard Hull

[Tom Dressel]

Twenty one years of sucking bad air.

I don't spend much time in the basement now, but in the past I have spent hours down there watching TV and my wife now sits down there for hours watching DVD's.

$1,425.00 is not inexpensive, but remember the radon detector was under $100.00. At least now the house is sellable, and the Radon guy is confident that the levels will be below 2.0 pCi/liter in a day or two.

[Richard Hull]

That is a very low price for the work done and product delivered, coupled with the peace of mind. It is comforting to know that at least one person directly benefited from this now long thread based on my original post. I am sure a lot of others who picked up the Radon Alert are better informed and happy they did.

A relatively inexpensive tool and instrument that looks at things unseen and reports to us on the world of radiation issues.

I am sure your levels will plumet. Radon remediation is often, just a matter of increased or improved ventilation rather than barrier blockage which is way more expensive.

Richard Hull

[Tom Dressel]

Well, 72 hrs of sucking under the slab has pulled the Radon level in the basement down from 38.5 to 0.9 pCi//liter. Thats a 97% Reduction.

Remediation works!

Tom Dressel

[richnormand]

Looks like that little detector was agood investment afterall!

[Tom Dressel]

Yes, it was a good investment.

A frend of mine who has a cabin on the north shore of Lake Superior, bought a series III detector and found Radon levels at 177 pCi/ liter in his basement.

I can't believe the apathy amoung my collegues ( all physicians ) with respect to Radon. After my experience, I feel quite strongly that a question that every primary care MD should ask their patient during the annual physical is: Do you know what the Radon levels in your home and work place are?

Tom Dressel

[Richard Hull]

Supposedly...............and I say, supposedly. Radon is second only to smoking as a causitive agent in lung cancer.

Whether this is an absolute fact or not is highly suspect. For I fear much of the data is based on old data where the population smoked a lot and others got a lot of second hand smoke plus there were high levels of other toxins. I am concerned that these elements could not be isolated enough to point 100% at radon as a causitive agent.

The only test I would ever accept is a control group that was 100% non-smoking and 100% not exposed to other chemical fumes in the work place being known to live in a highly radon loaded environment show increased cancer against a similar group in a known low radon environment.

Smokers vs. non-smokers is a no brainer, as the smokers willingly and gleefully exposed themselves every waking moment by setting tobacco on fire and sucking the burnt gases deeply into their lungs for that satisfying hit of pleasure.

No one would do that with radon and so such pronouncements such as "second only to smoking" for radon is highly suspect in my mind.

Still, erring on on the side of caution is also a no brainer. A 30+ pCi/l load is certainly not a happy living environment if it can easily be pulled back to 3 PCi/l. However, anything over 100 is a place you don't want to be for protracted periods. I bet a nickel to a doughnut that 10 p/Ci/l is just fine in a living space.

Some of the old U mines had daily working environments of 4000pCi/l! That is not a nice workplace. Of course 80% of those old miners smoked like chimneys, too! I was alive in the 40's and 50's and there were very few grown men who did not smoke. It was relatively rare to see a woman smoke then, but it became a common sight by the late 60's. Most U mines by the late 50's were well ventilated. I have an image taken deep inside the Mi Vida, where they have mined out a huge room (~40X40 feet?) and it is a formal welding and machine shop used to maintain the ore moving machinery. There are workers busy there at lathes and welding rigs. I don't think I would want to work in that shop, I don't care how well they ventilated it. I have seen movies of small mine operataions with the rock dust thick in the air. No one had on a respirator! How many radon induced cancers were logged here instead of being chalked up to direct dust inhalation or silicosis?

Richard Hull

[richnormand]

Here is another experiment for people with this neat detector. Usually it reads a constant 1 pC/l in the basement. However since radon comes from under the concrete slab I put the detector under a large beaker and over the basement drain. Here is the result after one week. now, since the drain has a water trap (and no smells) I have to assume this is coming from cracks around the fitting.