Rogeryermaw - 11-10-2010 at 00:02
i have a mercury thermometer with air trapped in the middle of the mercury. because of this i can't trust it's readings. i checked it against two
others that i have and they agree on temp down to less than half a degree but this third one is near 30 degrees off. it was then that i noticed the
bubble. is there a safe way to remedy this? i asked woelen about this and his info was good but i dan't think it has cracks...can't rule it out but
the air space doesn't seem to get smaller or larger except at the high end of the temp range (100+ on 150C thermometer) at which point it may be
thermal expansion. is there any way to get the bubble out keeping in mind i don't have liquid N2 or is it a lost cause? should i harvest it for the
mercury if it is?
did a search and came up empty. found a bit on google but about alcohol therm and using N2 to fix.
[Edited on 11-10-2010 by Rogeryermaw]
metalresearcher - 11-10-2010 at 02:06
I think grab it firmly in your hand with the bulb down. Then do as if you throw it away (but keep ik in your hand of course). The centrifugal force
may force the Hg in the top of the capillary above the bubble down and remove the bubble. It may cost many 'throws'. The bubble is actually a vacuum.
This is how resetting of a mercury based fever thermometer works.
[Edited on 2010-10-11 by metalresearcher]
DJF90 - 11-10-2010 at 03:55
Yes thats one common method - be careful you don't let go of it otherwise you'll have a real mess on your hands. Here's what Cole Palmer have to say
on the matter: http://www.coleparmer.co.uk/techinfo/techinfo.asp?htmlfile=R...
Other links:
http://www.novalynx.com/reference-rejoining.html
http://www.sigmaaldrich.com/etc/medialib/docs/Aldrich/Bullet...
http://www.flinnsci.com/Sections/FAQ/answers.asp?questID=20&...
http://www.cannoninstrument.com/JoiningMercuryColumns.pdf
zed - 11-10-2010 at 14:48
http://www.skyview.co.uk/dept6/acatalog/Mercury_Splits.html
Try it. Seems like we used to use dry ice, but the fix might be case-by-case.
Rogeryermaw - 11-10-2010 at 16:55
thank you all for the links and ideas. it was more than i could dig up. i now have a few things to try and will report any success i have (unless i
break it). the first thing i did try was leaving it in the freezer for a while but i think the range is too low for that. i guess the next thing is to
try a hot oil bath(i'm reluctant to swing it unless its a last resort) could just replace it but it's a pretty nice thermometer i'd like to keep.
again thanks for the help.