This is rediculous. 4 thermometers at different temps *pics* - Page 2

Tehrab · 05/08/2007, 09:34 AM

I have multiple glass thermometers that all have seperate readings. Granted, they are within a single degree so I just calibrate my RK2's probe to the average.

Icefire · 05/08/2007, 09:50 AM

Temp gun aren't precise, -+ 2% easy.

Kiel'thalin · 05/08/2007, 10:05 AM

You need pure distilled/ro to make an accurate reading, this means the ice too, any impurities will throw off the readings. The ice water is 32Â°F if you do it correctly with pure water. It is alright if the thermometer touches the ice. You did use crushed ice correct? IME the glass thermometers are usually dead on (+/- one division) or they are way out.

dcombs44 · 05/08/2007, 10:39 AM

Just because water freezes at 32 F and 0 C doesn't mean that it can't be colder than that, correct?

Why do we assume that a cup of ice water is 32 F just because it has frozen water in it. If that ice came from a freezer that runs at 5 F then I would expect whatever comes out of that freezer to be 5 F, but maybe that's why I'm an accountant and not a science major.

Kiel'thalin · 05/08/2007, 11:35 AM

I am not assuming anything, that is just what it is, 32Â°F. That is what the method mentioned does, creates a 32Â°F sample. Go ahead and mix in some salt, you will go a lot lower than 32Â°F.

jeffbrig · 05/08/2007, 11:49 AM

Who cares if a thermometer is off by a couple of degrees? I would argue that repeatability of measurement is much more important than the exact number it gives you. Any thermometer should be able to provide that.

Tanks can handle a pretty broad range of temperatures. Just take note of the reported temp your tank runs, and monitor for unexpected changes.

dcombs44 · 05/08/2007, 12:13 PM

Quote:

Originally posted by Kiel'thalin
I am not assuming anything, that is just what it is, 32Â°F. That is what the method mentioned does, creates a 32Â°F sample. Go ahead and mix in some salt, you will go a lot lower than 32Â°F.

I didn't mean to insult anyone (if I did). I was simply asking. No need to get worked up. It just didn't make sense to me that it would always be 32 degrees, so I asked a question.

Kiel'thalin · 05/08/2007, 12:28 PM

You did insult, I have no clue actually why, it is just one of those things you need to push the "I Believe" button. The only reason it would be colder is from disolved minerals (impurities) in the water bringing the temp down below the freezing point.

RamPuppy · 05/08/2007, 12:37 PM

Kiel'thalin...

just because he didn't understand the science doesn't mean he was insulting. I read it 3 times and I still don't see where you took offense.

I think it is perfectly logical to assume that ice coming out of a 5 degree freezer could be potentially colder than 32 degrees. infact, it probably is, now mixing it w/ water probably averages it out and stabilizes it, but his question is valid.

also, please, to satisfy MY curiosity, my digital temp probes have plastic encasing the probe... how would mineral content affect temperature then? i would think that it would only be a factor if conductivity was an issue..

Kiel'thalin · 05/08/2007, 12:49 PM

That is where the Freezing point (0Â°C) and Boiling point (100Â°C) was established. Newton making a thermometer and setting calibration points. On his thermometer he made one point by melting ice in pure water, hence the mark was called 0Â°. Then boiling water to set another calibration point on his thermometer, 100Â° Sorry I am terrible at explaining things...

jimwat · 05/08/2007, 12:58 PM

Quote:

Originally posted by dcombs44
Why do we assume that a cup of ice water is 32 F just because it has frozen water in it. If that ice came from a freezer that runs at 5 F then I would expect whatever comes out of that freezer to be 5 F, but maybe that's why I'm an accountant and not a science major.

I'm not a science major either, but if you are measuring the temperature of the water in a liquid state (around the cubes), it can not be colder than 32 degrees or it would not be a liquid. Same thing for boiling, if the water goes above 212 it is not longer in a liquid state. Does that make sense?

And as long we are looking at slight variations due to impurities, wouldn't elevation also effect the boiling and freezing points?

RamPuppy · 05/08/2007, 01:18 PM

ok, so it's measuring the temperature of the water.. that makes sense.

just have to think about these things for a moment. (or 5)

Airman · 05/08/2007, 01:30 PM

They are accurate plus/minus 3.7 F

Kiel'thalin · 05/08/2007, 01:53 PM

Quote:

Originally posted by jimwat
And as long we are looking at slight variations due to impurities, wouldn't elevation also effect the boiling and freezing points?

Elevation does not matter with freezing, but is a factor in boiling...

dcombs44 · 05/08/2007, 01:54 PM

Quote:

Originally posted by RamPuppy
ok, so it's measuring the temperature of the water.. that makes sense.

just have to think about these things for a moment. (or 5)

I think I get it. The water (not frozen) is in constant contact with something that is frozen which lowers the water temp to the brink of freezing. I guess that seems logical. I'm assuming the variable here is that you use water that's fairly cold from the start??

So I suppose the issue may be the other direction in that the water may be warmer than 32 degrees.

Isn't this fun.

Oh, and stupid me for not thinking that water can't be colder than 32 degrees. Small brain fart on my part.

RamPuppy · 05/08/2007, 03:52 PM

dcombs,

not stupid, the ice CAN be colder than 32 degrees and it can come in contact w/ the probe.. I think the general principle here though is that the water, no matter what, will be in more contact w/ the probe than the ice will, of for no other reason than capillary action there will be water between the ice and the probe.. so when you really chew on it, no matter how cold the ice is, it's the water that matters, and the water that will contact the probe.

05/08/2007, 09:50 AM	#27
Icefire Seasoned reefer Join Date: Jan 2007 Location: In Quebec, Canada Posts: 3,653	Temp gun aren't precise, -+ 2% easy. __________________ Temp 80F, PH 8.5-8.0, Alk 6.8-7.2, Ca 430, Mg 1700, NO3 0-0.25, PO4 0.04, 34.4 PPT Lights @ 100% all others, 35% White Current Tank Info: 60g Cube, 120lbs live rocks, Hydra52 2x120W, 2 MP40+ 1 MP10 @ 70%, Phosban 550 GFO+Carbon, 200W Heater, SWC Skimmer, Kalk ATO, 150 gpd RODI

05/08/2007, 10:39 AM	#29
dcombs44 Registered Member Join Date: Jan 2005 Location: Southern Illinois Posts: 2,913	Just because water freezes at 32 F and 0 C doesn't mean that it can't be colder than that, correct? Why do we assume that a cup of ice water is 32 F just because it has frozen water in it. If that ice came from a freezer that runs at 5 F then I would expect whatever comes out of that freezer to be 5 F, but maybe that's why I'm an accountant and not a science major. __________________ Current Setup: 10 Gallon Skimmerless Zoanthid Tank Lighting: Single 175 Watt Metal Halide (14,000 K Hamilton Lamp) Filtration: 10 gallon sump/refugium and Phosban Reactor Return: Mag Drive 700 Controller: ReefKeeper Lite (Basic Version) Circulation: TBD Age of System: Build is in Progress

05/08/2007, 11:49 AM	#31
jeffbrig Premium Member Join Date: Mar 2004 Location: Ft. Lauderdale, FL Posts: 5,548	Who cares if a thermometer is off by a couple of degrees? I would argue that repeatability of measurement is much more important than the exact number it gives you. Any thermometer should be able to provide that. Tanks can handle a pretty broad range of temperatures. Just take note of the reported temp your tank runs, and monitor for unexpected changes. __________________ Beware the power of stupid people in large groups..... Current Tank Info: formerly 250g room divider

05/08/2007, 01:30 PM	#38
Airman Registered Member Join Date: Aug 2005 Location: Boise, ID Posts: 643	They are accurate plus/minus 3.7 F __________________ What is man, that thou art mindful of him?...:) Current Tank Info: 55 Gal, DSB, protein skimmer, UV light, Sump/Refugium

05/08/2007, 09:34 AM	#26
Tehrab Registered Member Join Date: Dec 2006 Location: Reno, NV Posts: 116	I have multiple glass thermometers that all have seperate readings. Granted, they are within a single degree so I just calibrate my RK2's probe to the average.

05/08/2007, 10:05 AM	#28
Kiel'thalin Registered Member Join Date: Jun 2006 Location: Albany, Georgia Posts: 575	You need pure distilled/ro to make an accurate reading, this means the ice too, any impurities will throw off the readings. The ice water is 32Â°F if you do it correctly with pure water. It is alright if the thermometer touches the ice. You did use crushed ice correct? IME the glass thermometers are usually dead on (+/- one division) or they are way out.

05/08/2007, 11:35 AM	#30
Kiel'thalin Registered Member Join Date: Jun 2006 Location: Albany, Georgia Posts: 575	I am not assuming anything, that is just what it is, 32Â°F. That is what the method mentioned does, creates a 32Â°F sample. Go ahead and mix in some salt, you will go a lot lower than 32Â°F.

05/08/2007, 12:28 PM	#33
Kiel'thalin Registered Member Join Date: Jun 2006 Location: Albany, Georgia Posts: 575	You did insult, I have no clue actually why, it is just one of those things you need to push the "I Believe" button. The only reason it would be colder is from disolved minerals (impurities) in the water bringing the temp down below the freezing point.

05/08/2007, 12:37 PM	#34
RamPuppy Registered Member Join Date: May 2003 Location: San Antonio, Texas Posts: 531	Kiel'thalin... just because he didn't understand the science doesn't mean he was insulting. I read it 3 times and I still don't see where you took offense. I think it is perfectly logical to assume that ice coming out of a 5 degree freezer could be potentially colder than 32 degrees. infact, it probably is, now mixing it w/ water probably averages it out and stabilizes it, but his question is valid. also, please, to satisfy MY curiosity, my digital temp probes have plastic encasing the probe... how would mineral content affect temperature then? i would think that it would only be a factor if conductivity was an issue..

05/08/2007, 12:49 PM	#35
Kiel'thalin Registered Member Join Date: Jun 2006 Location: Albany, Georgia Posts: 575	That is where the Freezing point (0Â°C) and Boiling point (100Â°C) was established. Newton making a thermometer and setting calibration points. On his thermometer he made one point by melting ice in pure water, hence the mark was called 0Â°. Then boiling water to set another calibration point on his thermometer, 100Â° Sorry I am terrible at explaining things...

05/08/2007, 01:18 PM	#37
RamPuppy Registered Member Join Date: May 2003 Location: San Antonio, Texas Posts: 531	ok, so it's measuring the temperature of the water.. that makes sense. just have to think about these things for a moment. (or 5)

05/08/2007, 03:52 PM	#41
RamPuppy Registered Member Join Date: May 2003 Location: San Antonio, Texas Posts: 531	dcombs, not stupid, the ice CAN be colder than 32 degrees and it can come in contact w/ the probe.. I think the general principle here though is that the water, no matter what, will be in more contact w/ the probe than the ice will, of for no other reason than capillary action there will be water between the ice and the probe.. so when you really chew on it, no matter how cold the ice is, it's the water that matters, and the water that will contact the probe.