Calibrating thermometers?

marcelft · 11/10/2008, 05:07 PM

OK..I have two thermometeres, a digital one says Im at 75.2 degrees, and a red lined old school termometer that says I'm at around 79 degrees. How do I tell which one, if either, is correct?

kolosy · 11/10/2008, 05:15 PM

buy a third.

seriously, that's what i did.

marcelft · 11/10/2008, 05:31 PM

Quote:

Originally posted by kolosy
buy a third.

seriously, that's what i did.

Now that's funny...but I hate math, even though finding the mean of three numbers isn't to difficult. There has to be a better way.

How about sticking them in a glass of crushed ice water, should read 32 degrees right?

buccard · 11/10/2008, 05:50 PM

Quote:

Originally posted by marcelft

How about sticking them in a glass of crushed ice water, should read 32 degrees right?

I have had the occasion to calibrate a thermometer in my line of work and that is exactly how I do it! ice and water in the same system have to be at 32 degrees just make sure the mixture is consistent. Ice just on top 2 inches of an 8 inch glass of water may give inaccurate reading depending on the depth you sample.

You can also use the other end...boiling water @ 212F if your thermometer operates in that range...more risky though.

marcelft · 11/10/2008, 08:16 PM

Quote:

Originally posted by buccard
I have had the occasion to calibrate a thermometer in my line of work and that is exactly how I do it! ice and water in the same system have to be at 32 degrees just make sure the mixture is consistent. Ice just on top 2 inches of an 8 inch glass of water may give inaccurate reading depending on the depth you sample.

You can also use the other end...boiling water @ 212F if your thermometer operates in that range...more risky though.

Ok..so I dropped my Marineland digital thermometer and regular red-lined thermometer in a glass of RO/DI ice water and the digital reads 30.1 degrees, and the redline reads 34. So, both are wrong in the opposite direction!! But, the mean of the two does equal 32!!

buccard · 11/10/2008, 08:47 PM

LOL...take the average!

marcelft · 11/10/2008, 10:25 PM

Mean = average. Just one more way of saying the same thing and confusing us all.

11/10/2008, 05:07 PM	#1
marcelft Registered Member Join Date: Aug 2008 Location: Boynton Beach, FL Posts: 540	Calibrating thermometers? OK..I have two thermometeres, a digital one says Im at 75.2 degrees, and a red lined old school termometer that says I'm at around 79 degrees. How do I tell which one, if either, is correct?

11/10/2008, 05:15 PM	#2
kolosy Registered Member Join Date: May 2008 Location: chicago Posts: 655	buy a third. seriously, that's what i did. __________________ not yet. maybe someday. Current Tank Info: 90L RR mixed reef, panworld 150ps external pump, t5/mh/led, 20g under-tank sump, 27g above tank sump, 27g fuge with 4" dsb, macro and lr rubble.

11/10/2008, 08:47 PM	#6
buccard Premium Member Join Date: Oct 2008 Location: Lakeland, Florida Posts: 970	LOL...take the average! __________________ Roger Save a fish, click on the red house. Current Tank Info: 90 Gallon-mixed reef

11/10/2008, 10:25 PM	#7
marcelft Registered Member Join Date: Aug 2008 Location: Boynton Beach, FL Posts: 540	Mean = average. Just one more way of saying the same thing and confusing us all. __________________ Marcel Current Tank Info: Outside tank = 343,423,668,428,484,681,262 gallons of water..nick named "The Ocean". Inside tank 75g.