Thermometers

[blucoondawg]

What is the most accurate thermometer hygrometer available? The ones on my Farm Innovators incubator are off I am reasonable sure, so far I have tried 3 different cheap thermometers which all read different, like none are calibrated properly and I don't know which to believe, I put them all close together so they should all be pretty much the same temp. I tried a cheap reptile hygometer and I don't know if I can trust that either.

What thermometers or hygrometers have you found accurate? I am thinking I need to find a old style glass medical thermometer and some sort of hygrometer, I think I could trust a medical thermometer more easily than all these cheapo weather thermometers. I also don't want one that is going to take up a ton of room in my bator like the larger digital ones without probes

 

[Egghead_Jr]

You can spend a lot on either of those or a combination. Then there are children thermometers I trust to be accurate to check/calibrate whatever cheapo thing I've got in the incubator. And there is a salt test you can perform on your cheapo hygrometer or combo hygrometer/thermometer to calibrate it's accuracy.

From there you just make a note on a piece of tape and stick it on your incubator to remind you your thermometer is this many degrees high or low and same with hygrometer.

Salt test:

Put salt in a milk cap or similar holder.
Add drops of water until it becomes a paste. Not a slurry but paste.
Put hygrometer and cap in a sealable bag or very small tuperware.
Wait 6 to 8 hours and take the reading. How ever far off it is from 75% is your calibration.

Here is an inexpensive (moderately so) digital combo unit I use and actually reads very accurate temp and you can adjust the humidity readout to calibrate:

http://www.ebay.com/itm/HygroSet-II...396?pt=LH_DefaultDomain_0&hash=item3a894d6314

 

[blucoondawg]

I saw a similar salt test on here on a different thread though it didn't say a milk jug lid and gave some specific measurement, I will try this but I guess I don't understand the physics behind it and why it would work, wouldn't the humidity reading depend on factors such as size of the container it is in, and how much water is in the salt mixture, or maybe how much surface area of moist material there is allowing X amount of water into the air? I just don't get how the correct answer would always be 75% humidity with all these variables.

 

[Egghead_Jr]

All salts and other things crave for a certain humidity at almost any temperature. They absorb or emit moisture to do so. Your correct in thinking if the container is too large and amount of salt you use too small it will simply dry out before emitting the water you added.

Ziplock sandwich bag and milk cap size of salt works very well.

Here's a chart on other salts and the accuracy of sodium chloride in a wide range of temperature.

http://www.omega.com/temperature/z/pdf/z103.pdf

 

[aart]

Here's what I use to test my thermometers and hygrometers....hope it helps:

Tips on checking accuracy of thermometers and hygrometers:

The thing you want to do is check that any of thermometers and hygrometers are correct by testing them against a known criteria.
Comparing devices is useless unless you know how accurate any of them are.

I used a candy thermometer tested in boiling water and noted how far off 212 degrees it was...or whatever temp water boils at your altitude.
You can check your boiling temp at altitude here.
Then put the candy thermometer and 3 others in the incubator during the test run and compared them all, noting any differences.
I made a chart noting all temps and made notes about if this one reads this temp it is actually that temp.

Hygrometers can be tested by putting 1/2 cup salt and 1/4 cup water in a dish or jar and mixing it to a slurry.
Put the salt slurry jar and the hygrometer next to each other in a sealed plastic bag.
After 8-12 hours the hygrometer should read 75%...again note and differences and you're set.

 

[dickhorstman]

Thermometers can be checked by filling a glass with crushed ice or small cubes and filling with water. Your thermometer should then read 32 degrees.

 

[HatchCraft]

I don't think there is a good way to calibrate a thermometer at home . Boiling water and freezing water temperatures are to far from 100 degrees to accurately calibrate. Just because its right at 32 doesn't mean it's right at 100. I my opinion and experience, the best way is to buy a quality and accurate thermometer to begin with. I suffered from the same frustrations as everyone else until I bought a pair of robins dry bulb thermometers from Philadelphia Instruments made for incubation and haven't had to guess at temps for a decade. They measure temp over a narrow range 88 -108 deg. I use a wet bulb thermometer to calibrate my digital hygrometers. They sell other models as well including very expensive calibrating thermometers. I think I paid 30.00 apiece plus shipping. There are accurate, compact about 6", and graduated in 1 deg increments but you can easily calculate in factional degrees. The cons, they are glass , fragile and contain mercury . They also can be hard to read like all mercury thermometers they must be viewed at the right angle to see the mercury column. I use mine when setting up incubators to confirm the accuracy of digital controllers and thermometers and then put them safely away. I'm sure there are other manufactures of high quality digital and analog thermometers, this is the one I have experience with.

 

[aart]

That is true HatchCraft...but...most people don't have the bucks to buy certified calibrated instruments.....and that's also why I used the term 'tested' instead of 'calibrated'.

It is a comparison between thermometers and hygrometers, not a calibration. The word 'calibration' is misunderstood and misused by a lot of people. I've had a lot of experience using certified calibrated measuring devices working in the engineering field for 20 years.

This is was the closest I could come to at least testing a number of thermometers and hygrometers so at least I knew what the differences on them were and could adjust my readings and not wonder which was right or wrong because of readings that varied by as much as 10 degrees when trying to maintain a range of ~2 degrees in a incubation environment.

dickhorstman...I used a glass candy thermometer and boiling water because it was the only thermometer I had that I could get wet, read in the range I needed and could compare to the others in the incubator environment.