US source for Tritium markers..

[John N]

Re: New, US source for Tritium markers..

Well, I thought about it a bit, and while I am not concerned about safety from a personal perspective, I started wondering about risks in this litigious society.

In the end I decided I didn't need the hassle and cancelled the order.

-john

 

[JJHitt]

Re: New, US source for Tritium markers..

James: thanks for the link on watch dots. The CFR cites are exactly the sort of thing I'm interested in. I realize it takes a high boredom threshold to read, but I'm not a stranger to the CFR.

 

[6pOriginal]

Re: New, US source for Tritium markers..

[ QUOTE ]
James S said:
If you try to order from a source that imports them or sells them in the US they will have to verify your storage and disposal facilities and you'll have to do a lot of paperwork and may be denied the license to have them. certainly if you say on the form that you're putting one on your keychain they will not OK it /ubbthreads/images/graemlins/smile.gif



[/ QUOTE ]

So have anyone ever got into trouble from buying/importing the glowrings? According to these articles, seems like the customs are not supposed to let them thru

 

[dreamlogic]

Re: New, US source for Tritium markers..

[ QUOTE ]
mrorange said:
Well I feel like an idiot now for even posting this, I should have checked it out further first....

[/ QUOTE ]

i'm glad you did post. it's been quite informative. thanks!

 

[JJHitt]

Re: New, US source for Tritium markers..

So... did anyone buy the large 5 inch model? And is it bright enough to read a map with dark adapted eyes?

 

[James S]

Re: New, US source for Tritium markers..

I'm not aware of anyone that has gotten into any trouble over the keychain models. I'm sure it would have been posted here if anyone had had any trouble /ubbthreads/images/graemlins/smile.gif

I do not believe however that anyone who is not purchasing it to mark a runway will be able to buy the 5" model. So don't expect to get much in the way of a review.

 

[Frangible]

Re: New, US source for Tritium markers..

[ QUOTE ]

I believe part of the issue was if you inhale gases tritium one of the disintigration daughter products is solid particulate and can lodge in the lungs, continuing to give off radiation from INSIDE the body till it decays! Just perfect condition for creating a cancerous growth in the lungs. Radioactive fallout outside the body is simply washed/scrubbed away in the shower, but what to you do when it's inside the body?


[/ QUOTE ]

Tritium contamination is indeed no joke, however it decays into a stable isotope of helium. Tritium has a halflife of 11 days in the human body and tends to be flushed out relatively quickly.

It's not nearly as dangeorus as other radioisotopes, but still needs to be handled safely.

 

[Tomas]

Re: New, US source for Tritium markers..

My understanding is that tritium has a 'half life' of 12.3 years, and that's not changed by being ingested or inhaled - the 11 days is how long before 50% is flushed out of the body 22 days for 75%, etc.

 

[Double_A]

Re: New, US source for Tritium markers..

Here are three excerpts from a DOD manual available via Google search. If I had thought about it a little harder I would have realized such a simple element/isotope cannot have any physically solid daughter products.


"Metals react with tritium in two ways by plating (the
process by which a thin film of tritium is deposited on
the surface of the metal) and by hydriding (the chemical
combination of tritium with the metal). In either
reaction, the surface of the metal will become contam-inated
with radioactive material."

"With the proper catalyst i.e., fire, tritium combines
spontaneously with oxygen in the air and will also replace
ordinary hydrogen in water or other hydrogenous
material (grease or oil), causing these materials to
become radioactive."

"The hazardous nature of tritium
is due to its ability to combine with other materials.
Tritium water vapor (TO or HTO) is readily absorbed
by the body, both through inhalation and absorption
through the skin. The radioactive water that enters the
body is chemically identical to ordinary water and is
distributed throughout the body tissue. Although it takes
a relatively large amount of tritium to be a significant
radiation hazard, caution should be taken. Tritium which
has plated out on a surface or combined chemically with
solid materials is a contact hazard. The human body
normally eliminates and renews 50 percent of its water
in about 8-12 days. This turnover time or biological
half-life varies with the fluid intake. Since tritium oxide
is water, its residence time in the body may be
significantly reduced by increasing the fluid intake."


GregR

 

[mattheww50]

Re: New, US source for Tritium markers..

Tritium emits a beta ray that is about the same as the electrons that hit the screen on your CRT. Penetrating power is essentially zero.

The forming a surface film is called adsorption, and some metals, such as Palladium, are exceptionally good at it.

The big binds with substantial tritum sources is what happens to the tritium. It is a diatomic gas, or it may be part of polymer. When it decays you get Helium 3, which is an inert gas, so tritium sources always evolve helium 3, and if you are not careful, the sealed source will literally explode. Many such source actually have a vent plug so you can vent the Helium 3 periodically.

This isn't much of an issue with the tritium sources in places like Luminox watches, which are encapsulated in borosilicate glass. The glass walls are thin, and He3 diffuses through the spaces between the atoms fairly easily (Helium 3 is about the smallest gas molecule there is, and you'd be amazed at what it can diffuse through). Also if it was a gas to begin with, the pressure in the container can only double. The problem comes from sealed solid sources, such as polymers and hydrides.

As long as you don't drink it or inhale it, it is pretty hard to do much damage.

Interesting enough, neither tritium oxide or Dueterium oxide behaves exactly like water chemically. The difference in mass is enough to alter physics of the chemical reactions. I.E. both are less likely to become involved in chemical reactions then 'regular' water.

 

[John N]

So let's just say that you buy some of these, use them for the intended purpose as markers and you house burns down and the markers are destroyed. You'll need to report them destroyed. When that happens does that mean they will require some sort of expensive site clean up? I can just picture a million dollar clean up for a pesky $12 marker light.

On another related topic, what is the disposal procedure?

-john

 

[JJHitt]

From the Lab Safety website:

"When markers reach their expiration date, return to manufacturer for recycling."

 

[James S]

[ QUOTE ]
Interesting enough, neither tritium oxide or Dueterium oxide behaves exactly like water chemically. The difference in mass is enough to alter physics of the chemical reactions. I.E. both are less likely to become involved in chemical reactions then 'regular' water.

[/ QUOTE ]

Which is exactly why the method for concentrating deuterium in a water sample is via electrolysis. The deuterium is less likely to disassociate than the regular water and so the regular water goes away leaving behind more of the heavy water.

What this has to do with anything above I don't know, just interesting science tidbit /ubbthreads/images/graemlins/grin.gif

 

[Double_A]

Ok, I have a question for JamesS and Matthew, if in fact heavy water does not behave the same on chemical reactions, does that mean it will not behave the same in biological processes within the body?

Is anybody here a Radiation Health Physicist? or anybody know one? that they could ask?

GregR

 

[paulr]

A quick Google search finds the following:

http://www.madsci.org/posts/archives/sep99/937181271.Ph.r.html

My possibly wrong back of the envelope calculation goes like this: 1 gram of tritium = 1/3 mole = 2e23 atoms. With 11 year half-life that means a gram of tritium is about 5e14 Bq. (1 Bq = 1 decay per second). So the linked article says that ingesting 1 milligram of tritium is enough to be fatal.

If the gas in the glass capsule is pure tritium with 1 ml volume and at atmospheric pressure, the tritium mass would be about 1/60 of a milligram (22.8 liters per mole, 3 grams per mole), which does not sound like an amount I'd want to drink or breathe if only 60x that amount is guaranteed fatal.

I remember also reading that breathing 1 microgram of plutonium dust would almost certainly cause lung cancer. It's of little comfort that the alpha emissions can be stopped by a barrier as thin as a sheet of newspaper, since the insides of our lungs are not lined with newspaper.

I also remember calculating a while back that the power emission of decaying tritium is about 1 watt per gram of tritium. So if you could get that out as electrical power somehow, an amount the same mass as a CR123A battery would make over 10 watts of power, which would run a Surefire E2e with power to spare for several years nonstop.

This is all based on high school physics which I mostly forgot a long time ago, so it may be full of mistakes.

 

[Frangible]

I tried checking your math and got as far as the number of atoms etc but wasn't sure about how to go from that to Sieverts. How did you calculate that?

 

[paulr]

Sieverts are a measure of biological radiation dose, like rem. The article I linked to had a conversion factor from Bq (Becquerel) to Sieverts. I'm not sure how they figured it out. 1 Bq is just one atom decaying per second. If you have a gram of tritium, you know how many atoms that is from the molecular weight (oops! I guess the molecule would be H2 and not just H, so the molecular weight for 3H would be 6 and not 3, so there's a mistake in my earlier post already). Say it's N atoms. From the half life (11 years) you know that N/2 atoms decay in 11 years. I then made a rough approximation that the same number decay every second. Of course the number really follows an exponential decay so the rate is twice as high at the beginning as at the end, so the approximation is off by a factor of 1.4 or something like that, but these are all very rough numbers anyway, so I didn't worry about it.

 

[Frangible]

Hmm ok, I'm still not really sure how that site got from activity to absorbed dose.

 

[paulr]

I think absorbed dose is determined from the radiated energy (something like 18 keV per decay for tritium) but also adjusted by some experimentally determined biological factor that depends on the particle type and the energy.

 

[LED07]

Photoluminescent vs. Tritium

One could think, if tritium has this disadvantage, why use it? There's different reasons. Photoluminescent and Tritium are the two types of non-electrical exit signs that are available on the market today. Non-electrical photoluminescent and tritium powered exit signs have gained popularity since they were introduced for a number of reasons.

Non-electrical exit signs are favored over electrical exit signs:
1. From a new construction standpoint, they eliminate the time, labor, and
supply costs of running a dedicated emergency circuit for exit signs.
2. From a retrofit construction standpoint, they eliminate the invasive and
expensive cost of hiring an electrician for installation.
3. From a maintenance standpoint, there are no wires, batteries, or movable
components to maintain.
4. Because they can last 20 or more years, whereas LED exit signs last 8 to
10 years.
5. Because they can help attain LEED points which work toward the USGBC
LEED Certification Program.
Non-electrical exit signs are tested and certified to the same standard (UL 924)
as electrical exit signs. Carrying the UL 924 Listing means that non-electrical exit
signs can be used in the same applications as conventional electrical exit fixtures
with no additional approvals needed. The non-electrical exit signs that we carry
are UL 924 Listed for both the United States and Canada.

Photoluminescent exit signs use industrial grade glow-in-the-dark pigment to illuminate in dark conditions. While the lights are on, the supercharged photoluminescent pigment charges itself by absorbing light. When dark conditions are present the sign will glow for a minimum 90 minutes. Photoluminescent exit signs have a 20-year lifespan as long as the face of the sign is kept clean. They are offered with viewing distances
of 50, 75, and 100 feet. Photoluminescent exit signs are suitable for indoor
applications in commercial facilities where the lights are on while the building is occupied.
Tritium exit signs use tritium gas, an isotope of hydrogen, to self-illuminate. Tritium gas is inserted into shatterproof glass tubes that are coated in a phosphor.
When the tubes are sealed, the tritium interacts with the phosphor and produces a green glow that requires no outside power source or light for illumination. Self- luminous tritium powered exit signs are available in 10 and 20 year service lives. Self-luminous exit signs are available with viewing distances of 100 and 125 feet.
Self-luminous tritium powered exit signs are suitable for indoor and outdoor
locations, including extreme environments and hazardous locations.