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Barometer repair

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Hudson Carpentry

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Client has asked me if I know anyone. I said ill ask around so does anyone know how to repair them and would be interested in doing the repair?

Some of the mercury has came out, the bung was removed. I have some pictures if it helps?
 

Jonzjob

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Piktures, piktures! Them always help man!

If it has a mercury resevior in the base it could possibly be repaired? Does the said removed bung sit in the resivoir in the bottom or the top of the tube? The top of the tube should be sealed, but not always?

This link could help? http://www.jce.divched.org/JCESoft/CCA/ ... /CD2R1.HTM

Crikey, I haven't worked with mercury manometers since I was an aircraft eleky in he R.A.F.!!
 

Eric The Viking

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RogerS":6kxcatm4 said:
There's a place in Leominster. Here http://www.thebarometershop.co.uk/
I've been in there - they certainly know their stuff, and some of their barometers are really beautiful.

Gotta love the EU... there are 'issues' with mercury barometer repair now. I believe they can do repairs using customer-supplied mercury, but not supply it themselves. There's stuff on their site about it.

In all seriousness though, if enough mercury has leaked to be noticeable, the owners ought to attempt to find it. It tends to collect below wooden ground floors, and the vapour really is quite a health hazard. Nobody would really want to end up like this:



Regards,

S.
 

Jonzjob

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When I was stationed at R.A.F. Lyneham we had a Britannia written off by an silly person shipping a mercury barometer out to Singapore without telling anyone what it was. The mercury leaked into the luggage bay and then onto the inside of the belly of the aircraft. When mercury hits aluminium it forms flowers of mercury wich is even mor corrosive than the original. There was no way riggers could tell how far it had gone and the aircraft was scrapped.

Beg pardon, it wasn't a barometer, it was a manometer. Same sort of pressure indicating instrument though :mrgreen:

It looks as if that shop do repairs on clocks and watches too. I think I'll contact them about a possible repair to my Waltham pocket watch?
 

Jonzjob

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Sorry if this is egg sucking time, but the mercury barometer works on the principle of how much of a vaacume can support a coloumb of a liquid. In this case mercury.

You have a set amount of mercury and you completely fill a tube with one end sealed so that there is no air in the tube. The tube has a 'u' bend in the bottom with a small resevoir formed by a goblet shaped form. The tube assembly is turned so as to be verticle and the sealed end uppermost. The atmospheric pressure works on the surface of the mercury in the resovoir but is not enough to hold the vacume so the mercury in the now upright tube will drop down the tube untill the pressure pressing on the surface of the mercury in the resevoir equals the amount of vacume that can stop the mercury dropping any further. It is then calibrated with a known master barometer and you have a barometer which is about as accurate as you can get! The bung in the resevoir is not airtight, or should not be..

Now, if your barometer still has a totally full tube of mercury when VERY carefully layed horizontally and no air had got into the top then as far as I can think all it needs is for the escaped mercury to be put back into the resevoir and the bung replaced, but not sealed. BUT! Quite how you would know if any mercury is missing I have no idea.

Also remember that mercury is a BIG HAZARD when let loose and the fact that I, and my fellow apprentices, used to play with the stuff when we were being trained in 1960/61 at St Athans? Just be very carefull!

Just as a matter of interest, you can make a barometer with water instead of mercury. Much safer, but instead of about a 32" coloumb you will need a 32' (foot) one! So if you do then can you tell me how you convince the OH to poke a hole through the lounge ceiling and roof?

In retrospect, it's probably best left to the pros?

As a further matter of interest. I want one!!!
 

Hudson Carpentry

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Thanks Jonz

As no one has stepped forwards ill contact them in the link if customer is happy to ship the item out.
Im worried about shipping it out, also is it allowed to post these containing mercury??
 

Eric The Viking

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It looks very smart for an Admiral Fitzroy (he of 't shipping area). Is it new-ish or restored?

The problem isn't a big one, as John says. It's simply a matter of re-establishing the (Torricellian) vacuum properly, at the top of the sealed end of the tube. The people in Leominster can do this, easily.

Watch out for the escaped mercury though. It can get out of the case, just like water could. The best thing would be to place the whole thing in a plastic bag (bin liner?). There will be a significant vapour pressure behind the glass - keeping it as cool as possible will help, too, until you get it to a restorer to fix it.

Aside: my own, unrestored barometer is the banjo type (C19th). The only real difference with the Fitzroy ones is that there is a float and a mechanical linkage to the needle. It's still got a mercury column arranged in a similar way. Happily, so far, nobody has lain it down or inverted it, but when I get a round tuit, it'll be making the trip to Leominster too, well two trips, actually, I hope. The first one will be to remove the mercury, allowing me to restore the case, then I'll get it set up again once it's done.

Regards,

E.
 

Jonzjob

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Did you know that you can get a whole pound of mercury from a manometer into an old fashioned aircraft aneroid altimeter :oops: :oops: You can't get it back out again without destroying the instrument either :oops:

When I was doing my instrument training at R.A.F. Newton I managed to do just that! The instructor was not impressed :roll: :roll: :mrgreen:

The people at Leominster will be able to tell you how to pack and send it.
 

Jonzjob

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I phoned the barometer shop this morning to find out about the possible repair to a silver pocket watch I have. At the end of the call I asked about repairs to mercury barometers and he said no problems but that you would have to take and collect it. Still worth the call though. He was very helpful and may well be able to advise you about the best way to go about doing it yourself?

Shame I didn't need the repair to my watch before we moved over because we lived very near Stroud and Leominster (pronounced Lemster) isn't too far away form there..
 
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