Heavy metal

This topic has 18 replies, 14 voices, and was last updated 23 August 2017 at 18:04 by Neil Wyatt.

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18 August 2017 at 11:26 #25451
Cornish Jack
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@cornishjack
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18 August 2017 at 11:26 #312672
Cornish Jack
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@cornishjack
G'dy all.

I'm sure there has recently been a thread dealing with heavy metals but I can't find it. Heavily into workshop tidying/clearing and found, in my toolbox, a 2.25" x 5/8"(That's fradections!!) round bar. It is VERY heavy and (from memory) was purchased some 30 years ago to provide crankshaft balance for a home-built Matador 60 – (never completed, of course!!) The few remaining brain cells say that this was depleted uranium (dull, dark grey colour?). Any clues as to how to identify it, please?

rgds

Bill
18 August 2017 at 11:50 #312678
duncan webster 1
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@duncanwebster1
measure it's specific gravity by weighing it in air then submerged in water. The difference gives you the weight of water displaced, and 1 kg of water weighs 1 kg, so you can work out the volume. Divide the weight in air by the volume and hey presto.

If you suspect it is uranium, don't be tempted to cut it, it is an alpha emitter and a heavy metal poison, so inhaling the dust would not be a good idea. Uranium is 18.9 kg/litre, tungsten is 19.6. The difference is enough if you're careful with your measurements. Freshly machined Uranium is silvery white, but it oxidises fairly quickly to a dull dark grey colour. Search wikipedia for a photo.

Just hope it isn't Uranium as getting rid of it safely and legally will probably be a nightmare
18 August 2017 at 12:06 #312682
Henry Artist
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@henryartist43508
A Geiger counter might be useful…

They're not cheap to buy though quartz fiber dosimeters can be obtained for a reasonable sum.

If it turns out to be a ferrous metal you could do a Spark Test. Section 7.4 of "The Model Engineer's Handbook" by Tubal Cain has the details for this.

The next test would be to determine the specific weight and density of the material. For this you need to know the weight (easy enough to determine) and the volume it occupies. To calculate the volume either measure it or immerse it in a liquid and see what volume it displaces. Then it's just a matter of looking up the density of the material you have.

If it happens to burst into flames when immersed in water then there's a good chance it was a bar of sodium…
18 August 2017 at 12:12 #312685
Hopper
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@hopper
Uraniium? Yikes.

Seems like it's more common to use either tungsten or Mallory metal for crank balancing. Are you sure it's not one of those?
18 August 2017 at 13:36 #312709
Swarf, Mostly!
Participant
@swarfmostly
There used to be an alloy called 'GEC Heavy Metal' (made by guess who?!) that was intended to be used for counter-weights to balance aircraft flight surfaces (elevators, ailerons & rudders). Dense was good as the counter-weights balanced at a shorter radius giving a smaller swept volume and so not needing as much space within the non-moving parts of the airframe.

I've no idea of its constitution. Perhaps Andrew knows?

Best regards,

Swarf, Mostly!
18 August 2017 at 13:49 #312711
Geoff Theasby
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@geofftheasby
Depleted uranium WAS used, but now Tungsten, I believe.

Geoff
18 August 2017 at 13:57 #312712
Geoff Theasby
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@geofftheasby
From PPPrune –

"RUDDER/ELEVATOR BALANCE WEIGHT – REMOVAL/INSTALLATION
1. General
A. This procedure includes removal and installation of balance weights for
the rudder and elevator while control surface is still installed on the
airplane. Balance weights can be made of tungsten or depleted uranium.
WARNING: THE RUDDER AND ELEVATOR MUST BE PROPERLY BALANCED AT ALL TIMES.
AN OUTBOARD ELEVATOR OR RUDDER THAT DOES NOT MEET THE
REQUIREMENTS SPECIFIED IN 51-80-02 OR 51-80-03 OF THE
STRUCTURAL REPAIR MANUAL CAN PRODUCE UNDESIRABLE FLUTTER AND
DYNAMIC INSTABILITY WHICH COULD AFFECT FLIGHT SAFETY.
B. Depleted Uranium Balance Weights
(1) Some balance weights on outboard elevator and upper rudder are made
from depleted uranium, which is a naturally occuring uranium that
has been "depleted" of most of the isotope U235. This remaining
low-level radioactive uranium, similar to other heavy metals, is
toxic if ingested, absorbed, or inhaled into the body. Those
weights are identified with legends permanently stamped into the
surface of each weight, to assure special handling during
maintenance. Protective coatings have been electro-plated on the
weights to contain the depleted uranium. If those coatings are
penetrated, certain precautionary measures are required to minimize
the small health risk.
WARNING: REWORK, SUCH AS FILING, SANDING OR MACHINING, THAT WOULD
DAMAGE THE PLATING OR REMOVE ANY BASE METAL IS PROHIBITED.
INHALATION OR INGESTION OF FILINGS, DUST, ETC., FROM THE
WEIGHTS MAY BE HARMFUL.
(2) Limited repair of damaged or corroded weights can be accomplished
safely if the procedures in subject 51-20-03, hazardous materials,
of the Structural Repair manual are used.
(3) Replacement of uranium balance weights with tungsten balance weights
can be obtained from Structural Repair manual (51-20-03)."
18 August 2017 at 14:21 #312716
Muzzer
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@muzzer
Posted by duncan webster on 18/08/2017 11:50:08:

measure it's specific gravity by weighing it in air then submerged in water. The difference gives you the weight of water displaced, and 1 kg of water weighs 1 kg, so you can work out the volume. Divide the weight in air by the volume and hey presto.

Surely you will get a much more accurate measure of its volume if you simply measure the diameter and length with precision tools, given that it is a length of round bar. I would expect the weight measurement to be the least accurate of the 2 unless you have some snazzy precision scales. The difference you cite between the densities is less than 4%, so your scales would need to be better than +/- 2% or so to be reasonably certain.

Murray
18 August 2017 at 18:14 #312769
Cornish Jack
Participant
@cornishjack
Thank you to all for the responses.

I'll do the S.G. calcs and see what gives. I'll also see if I can find the Matador 60 series in ME 'cos I think that I was trying to 'build to spec' and it would, presumably, have suggested appropriate material. Not sure if DU was regarded with such horror back then.

rgds

Bill
18 August 2017 at 18:57 #312784
Mark P.
Participant
@markp
We used to make really good riveting blocks from 707 ballance weights! These were I think DU.
Mark P
18 August 2017 at 19:34 #312791
Roderick Jenkins
Participant
@roderickjenkins93242
Bill,

The Matador 60 was published in RCM&E. I don't recall any requirement for extra weights for balancing, there's room for an adequately sized crank web.

Cheers,

Rod
18 August 2017 at 19:51 #312793
Neil Wyatt
Moderator
@neilwyatt
Why does this make me think of Repo Man…

Advice is to wear gloves to handle and don't try machining it.

Personally, I wouldn't walk around with it in my trouser pocket.

You can probably sell it for a hefty sum to a company that knows how and is able to use it safely.

Neil
19 August 2017 at 12:15 #312860
Ian S C
Participant
@iansc
If it's Uranium there will be little magnetic attraction, probably too small to be noticed. If it's Tungsten Carbide, it will possibly have either Nickle, or Cobalt in it and will be magnetic.

Ian S C
22 August 2017 at 20:25 #313434
Hevanscc
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@hevanscc
Depleted uranium has the most radioactive U-235 isotope removed, leaving the much less radioactive part behind, so you are more in danger of radiation from bits of Dartmoor granite. Having said that, uranium is a toxic heavy metal like lead so avoid inhaling the dust.

Hywel

Edited By Hevanscc on 22/08/2017 20:25:44
22 August 2017 at 21:26 #313444
not done it yet
Participant
@notdoneityet
uranium is a toxic heavy metal like lead so avoid inhaling the dust.

Except that uranium is radioactive and will be decaying inside you – not like lead which is just a nuisance and can be readily cleared from the system if diagnosed as a problem.

Alpha particles don't travel far, but are very destructive to dna etc due to their mass (compared with, say a beta particle which, while faster, has a mass of only 1/7000th of that of an alpha particle). Cannon ball versus ping pong ball comes to mind.
23 August 2017 at 07:48 #313483
Phil Boyland
Participant
@philboyland37326
If you can file off a tiny pioece and pop it in the post I can chemically analyse it for you in work. You will knoiw then exactly what it is.
23 August 2017 at 17:09 #313602
duncan webster 1
Participant
@duncanwebster1
Posted by Hevanscc on 22/08/2017 20:25:12:

Depleted uranium has the most radioactive U-235 isotope removed, leaving the much less radioactive part behind, so you are more in danger of radiation from bits of Dartmoor granite. Having said that, uranium is a toxic heavy metal like lead so avoid inhaling the dust.

Hywel

Edited By Hevanscc on 22/08/2017 20:25:44

Natural Uranium is typically 0.7% U235, depleted is typically 0.25% .

Granite can be 20ppm natural U, which is plainly a lot less U235 than DU

This website is very informative. I strongly recommend you don't file a bit off until you know it isn't Uranium.

**LINK**
23 August 2017 at 18:04 #313616
Neil Wyatt
Moderator
@neilwyatt
I strongly recommend you don't file a bit off until you know it isn't Uranium.

Ditto.
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