Re: Mercury artificial horizons
From: Bruce J. Pennino
Date: 2013 Dec 30, 18:23 -0500
Hello:
A year or so ago I refurbished a mercury artificial
horizon, and it was discussed here. USN No 6 mercury artificial horizon. Should
be easy to find, and I attached pictures of the metal jug. I think the first
containers (maybe Lewis and Clark vintage) were wood. I believe my jug is cast
iron or cast steel. I suspect iron because iron does not corrode as much as
other metals under many harsh conditions. The basin with the pouring nipple is
also cast iron. I believe any common metal or plastic would be ok because of the
short residence time of the Hg in the basin. My basin is 16 cmx 8cm x 1 cm
at max depth. Should use no more than 75% full because you don't want Hg
sloshing over the side.
I've intended to do a comparison of sights with my
mirron AH, but using the mirror is so easy I have not bothered with the Hg.
Whenever I transferred the Hg I always did it with a metal tray (a retired
8 inx 8 in cornbread baking pan) under the transfer. No matter
how careful you are, the Hg wants to roll here or there. Hg is now
considered a hazardous waste under EPA Rules and Regulations, so I suspect there
are many permits needed. Furthermore, people are afraid of it. Eventhough, like
many things , as long as you don't breath in the vapors for extended
periods, it is not a concern. As kids we played with it ( a long time
ago). I personally know of a college lab that almost got into
serious trouble when a jug of Hg was found in a closet.
My recommendation, use a reflecting basin and one
of the excellent AH designs that have been discussed here. Several fluids
have been discussed. With a triangular hood, the demonstration will be
fine, the data will be excellent. Should you decide to go ahead with Hg, the
diameter of the pour hole in the threaded spout must not be too large. I
estimate the diameter of my pour hole to be 1mm. If you really decide
to use Hg, I could get the diameter measured. I just filled the
AH basin with water and 1/2 cup of water USA filled the basin to the
very top to the point of over flow. Two thirds of this amount is sufficient
. The jug has a machined top surface, and the plug is threaded with a machined
sealing/seating surface. No other seals, but relatively fine thread with a
distinct "handle" on top so that it could be very tightly closed with a rod
through a hole or a pair of plyers. See the photos.
Regards
Bruce
----- Original Message -----
Sent: Monday, December 30, 2013 2:33
PM
Subject: [NavList] Mercury artificial
horizons
Will anyone who has used mercury for their AH answer a few questions for
me?
How much mercury is needed for how large a surface? (Ounces or
mililiters)
One photo showed a tray about 14 cm 4-5cm. How much to fill
this for use?
Can you name a source to purchase mercury?
How much does
mercury cost?
Should I use a wooden tray or metal?
Should the storage
bottle be metal?
Does mercury dissolve rubber o-rings?
Are special
permits from the EPA needed to buy or use mercury?
I understand toxicity is
low if you do not touch it or use it in an enclosed area. Is this true?
I am going to try to make a copy of the atique versions I have seen
pictures of, with the rextangular tray and the bottle threaded to facilittate
transfer back and forth.
Refer me to previous ppost if this has been
covered
before.
Randy
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