Want to avoid radioactive 5092 Nixies
ian_6500
I'm in the market for 5092-style tubes, but ones without radioactive
material in them. I read through many of the threads here and I know
some are of the opinion that there's no danger with the thorium or the
krypton, but I just assume avoid that material all the same. (Messing
around with anything that is or supposedly was radioactive seems like
a bit of an undue risk for my hobby.)
So, I need to buy four to six 5092-style tubes and I'm wondering what
models to search for that don't have radioactive material? Do the
Russian IN-4's and IN-1's have the radioactive material? Do all
Burroughs tubes?
And by the way, if I buy some Russian or Polish tubes (I have a set of
IN-2's) how do I tell if they have the radioactive material? I
understand that the American tubes are stamped with a radioactive
symbol. (The ones I have glow orange and not pink.) Any thoughts
would be great!
-Ian
Morgan Gangwere
> Hi Everyone,
>
> I'm in the market for 5092-style tubes, but ones without radioactive
> material in them. I read through many of the threads here and I know
> some are of the opinion that there's no danger with the thorium or the
> krypton, but I just assume avoid that material all the same. (Messing
> around with anything that is or supposedly was radioactive seems like
> a bit of an undue risk for my hobby.)
Here's a shock for you: Potassium is radioactive, and there's a fair
amount of it in bananas... enough so that they are used as a means by
which to show the amount of radiation leaked by reactors.
Plus, every day you'll experience maybe 10-40 times the amount of
radioactivity just by being alive (or, dare I say, standing next to a
few crates of bananas) than by dealing with a few (nee a /wall/ of)
5092's sitting on your desk for a lifetime.
As well, hate to say it
Krypton is used in:
Neon signage (it gives a nice blue glow)
Halogen bulbs (Again, nice incandecent blue glow)
MRI machines
High speed camera flashes
Arc discharg lamps
Spark-gap assemblies
Nixie tbues
Cold Cathode voltage regulators
> So, I need to buy four to six 5092-style tubes and I'm wondering what
> models to search for that don't have radioactive material? Do the
> Russian IN-4's and IN-1's have the radioactive material? Do all
> Burroughs tubes?
I'd go search through Dieter's nixie gallery until you find a nice
top-loading one that you like.
As anyone who's been on the list for a few years will know, I asked the
same questions you are when I got a few B5092's.
85kr is used in /some/ nixies as a means to make neon ignition go
faster. When I queried my chemistry teacher at the time (who was head of
Dow chemical for years) he offered this basic explanation:
- Neon and Xenon like being in daylight because they're bouncing around.
- 85kr couldn't give a damn.
When HV goes across the anode grid of the nixie, a sympathetic reaction
must occur. Either the Neon that's nearest the filament that has the
ground ignites, therefore glowing, or it /sits there/. Once its going
though, its A-OK. In the day time, the Neon doesn't have a problem
igniting, because there's actively photons heating up the glass just a
little.
However, when its dark around the bulb, the neon doesn't like to rapidly
come up. Instead, it will wait until things have warmed up a little.
the 85kr supplies a little bit of kick for the neon to get out of bed,
so to speak. Once HV goes accross the 85Kr, it springs into action and
emits photons, just enough to make the Neon start going. Think of it
like a cup of warm coffee and a bat to the head for the Neon.
All in all, the 85kr, being a beta emitter, will not /hurt/ you ( in
fact, its half life is 10 years or so)
> And by the way, if I buy some Russian or Polish tubes (I have a set of
> IN-2's) how do I tell if they have the radioactive material? I
> understand that the American tubes are stamped with a radioactive
> symbol. (The ones I have glow orange and not pink.) Any thoughts
> would be great!
Geiger counter?
--
Morgan Gangwere
>> Why?
> Because it breaks the logical flow of conversation, plus makes
messages unreadable.
>>> Top-Posting is evil.
jb-electronics
physics, and I got him a "radioactive" B-40225-AL (small 7mm special
symbol tube). We then measured the strength of beta decay (Kr85 emits
electrons), and there was nothing to be measured. So my guesses are: The
half life of roughly 11 years and the fact that electrons (beta-minus
radiation) cannot easily penetrate enything thicker than 3mm should make
you more confident that there is no harm coming from the "bad"
radioactive tubes.
Jens
John Rehwinkel
> amount of it in bananas... enough so that they are used as a means by
> which to show the amount of radiation leaked by reactors.
A bottle of salt substitute (potassium chloride), available at most grocery stores, will make a geiger counter cluck nicely.
> As well, hate to say it
> Krypton is used in:
That's ordinary krypton, not Kr85.
> Halogen bulbs (Again, nice incandecent blue glow)
Nope, you're thinking HID bulbs. Halogen bulbs contain halogens (like iodine or bromine), not krypton.
> High speed camera flashes
Nope, that's xenon.
> Spark-gap assemblies
Usually these contain something that resists ionization (like sulfur hexafluoride), not something that ionizes easily like krypton. For preionization (to reduce turn-on time or jitter), they usually use a beta emitter like Ni63.
> 85kr is used in /some/ nixies as a means to make neon ignition go
> faster. When I queried my chemistry teacher at the time (who was head of
> Dow chemical for years) he offered this basic explanation:
>
> - Neon and Xenon like being in daylight because they're bouncing around.
> - 85kr couldn't give a damn.
Basically, you're looking for something to initiate the ionization cascade. Photons can do this, which is why old neon bulbs will light better if it's not dark. While krypton is somewhat easier to ionize than neon or xenon, that's not why it's used. It's the radioactivity that keeps the gas slightly ionized so it will strike quickly when voltage is applied.
> When HV goes across the anode grid of the nixie, a sympathetic reaction
> must occur. Either the Neon that's nearest the filament that has the
> ground ignites, therefore glowing, or it /sits there/. Once its going
> though, its A-OK. In the day time, the Neon doesn't have a problem
> igniting, because there's actively photons heating up the glass just a
> little.
It's not a thermal process, it's an ionization cascade (or avalanche). What happens is the gas is an insulator, and refuses to carry charge between the electrodes. Until one atom gets ionized (by a high electric field, cosmic ray, local radiation, photon, or whatever). Then the electron gets pulled toward the cathode, and the ion gets pulled toward the anode. These smack into other atoms on their way, ionizing them, whereupon *those* charged particles start flying toward the oppositely-charged electrode and strike more atoms. In microseconds, there's lots of ionized gas, current is carried, and light is emitted.
> All in all, the 85kr, being a beta emitter, will not /hurt/ you ( in
> fact, its half life is 10 years or so)
This is true, as far as it goes. It emits beta particles (electrons) at 687keV. Nickel-63 emits much weaker beta particles at 67keV. The trouble with high energy beta particles is if they strike something with a high atomic number, they can emit Bremsstrahlung ("braking") radiation (X rays). With the tiny amounts we're concerned with here, however, the flux is too low to matter.
> Geiger counter?
You'd need a sensitive pancake tube to detect much of anything. I use a Black Cat Systems GM-45 and can detect counts noticeably above background with some of my tubes (mostly Western Electric gas tubes, TR tubes, and the like).
I can understand people wanting to avoid additiional radioactivity from nixies, just from an emotional standpoint, that's just a personal choice. Unfortunately, most of the non-US tubes aren't even marked, so you'd have to evaluate 'em with a geiger counter.
Just be glad you're not in the market for old-style voltage regulator tubes, some of which used all sorts of potent and exotic ionizers, including radium!
- John
threeneurons
>
> Just be glad you're not in the market for old-style voltage regulator
> tubes, some of which used all sorts of potent and exotic ionizers, including
> radium!
>
those really high voltage stabilizers like a 'coronatron', used in
early xerox machines ?
And just a reminder, this vintage technology makes us swim in other
hazardous materials, like lead solder, and mercury. Also cadmium
plated screws. I've handled all of those, and I ain't dead yet ... not
since I checked last.
ian_6500
in a nixie tube is to try and light it up in a totally darkened room?
If there are very few photons present, then I guess the tube wouldn't
light up until a cosmic ray or some other form of background radiation
triggers an ionization cascade. So, if there is a significant delay
lighting up, it might safely be assumed that anything radioactive has
decayed or was never present to being with? (I have a darkroom; I'm a
photographer.)
> I can understand people wanting to avoid additiional radioactivity from nixies, just from an emotional standpoint, that's just a personal choice.
and died of cancer. When I see a radiation symbol, I take it
seriously.
Unless of course, it's on a banana in which case I eat it with a
generous helping of salt-substitute while getting a suntan. :^)
@John, as always, thank you for your clearly-stated and thoughtful
reply--I enjoy reading your messages and have learned a great deal
from them! I also appreciate how you never use a condescending tone.
-Ian
A.J. Franzman
> So, perhaps a simple way to see if any radioactive material is present
> in a nixie tube is to try and light it up in a totally darkened room?
> If there are very few photons present, then I guess the tube wouldn't
> light up until a cosmic ray or some other form of background radiation
> triggers an ionization cascade. So, if there is a significant delay
> lighting up, it might safely be assumed that anything radioactive has
> decayed or was never present to being with?
since ionization time depends on a number of factors which make it
highly random, you should use as large a sample size as practical and
attempt to eliminate as many variables as possible. For example, use
nixie tubes which (other than having, not having, or being unknown
with regard to radioactive content) are as similar as possible -- type
B-5092 (without the "A" suffix) is supposed to be the non-radioactive
version of the B-5092-A/122P224. Other factors you can control are of
course the ambient light level, tube temperature, time since the tube
was last lit and supply voltage. I have personally seen ionization
times in the 30 seconds to 1 minute range, when using a barely
adequate supply voltage (full-wave recified 120 VAC) in a dark
environment with certain tubes that otherwise operated just fine.
A.J.