- Nov 2, 2012
- 30
- 4
- 31
We can almost take it as given that the dime-store, alcohol filled glass beastie is going to be way off but are we so confident that our digital instrument is any better?
I've bought a few digital ones over the years with a claimed accuracy of +/- 1C which is a bit too far off for my liking but I'll live with it - however, after pulling what's left of my hair out, I thought I'd try some.
This pretty basic school science. For our purposes at sea level, pure water freezes at 0C and boils at 100C - if you're at altitude, the BP drops a few degrees so that's something to watch out for - there's a table here: http://www.hi-tm.com/Documents/Calib-boil.html
I'm using a centigrade scale because it's simpler to make adjustments if you have to.
Melting, crushed ice should read pretty close to 0C on your instrument - be sure to stand the probe in there fully immersed and give it a good stir.
Deionized water (the stuff you put in your car battery) should boil at 100C which you can check on the stove - CAREFULLY because hot water is painful and I have the scars to prove it - provided your thermometer reads that high. If it doesn't, get yourself one that does.
With luck - your thermometer should read those values or very close to them - better than 0.3% is acceptable.
If it doesn't - not one of my "posh electronic" ones did - varying by +3 (at 0) and +96 at 100 degrees, then you're going to have trouble getting the right temp in your incubator.
To correct this (awful) error the best option is to throw the piece of junk in the bin and invest in a decent one.
As am I. ;-)
I've bought a few digital ones over the years with a claimed accuracy of +/- 1C which is a bit too far off for my liking but I'll live with it - however, after pulling what's left of my hair out, I thought I'd try some.
This pretty basic school science. For our purposes at sea level, pure water freezes at 0C and boils at 100C - if you're at altitude, the BP drops a few degrees so that's something to watch out for - there's a table here: http://www.hi-tm.com/Documents/Calib-boil.html
I'm using a centigrade scale because it's simpler to make adjustments if you have to.
Melting, crushed ice should read pretty close to 0C on your instrument - be sure to stand the probe in there fully immersed and give it a good stir.
Deionized water (the stuff you put in your car battery) should boil at 100C which you can check on the stove - CAREFULLY because hot water is painful and I have the scars to prove it - provided your thermometer reads that high. If it doesn't, get yourself one that does.
With luck - your thermometer should read those values or very close to them - better than 0.3% is acceptable.
If it doesn't - not one of my "posh electronic" ones did - varying by +3 (at 0) and +96 at 100 degrees, then you're going to have trouble getting the right temp in your incubator.
To correct this (awful) error the best option is to throw the piece of junk in the bin and invest in a decent one.
As am I. ;-)
thank you.
