Discussion of Thermal Sensing Techniques and Calibration

[Karasu]

I've been looking into upgrading my incubation equipment, and I'm curious what criteria folks here use when determining which category to select from. I've been leaning towards thermocouples myself, given that you can find units accurate to within +/- 0.5*F on Amazon for a fairly cheap price. As shown on the chart I shamelessly ripped from someone else, they do have their downsides, but I think they seem adequate for the job.

However, unless you're forking over the three or four digit prices for a NIST certified instrument, there are no guarantees on that accuracy figure. I'm lucky enough to have access to a dry well calibrator which I'm intending to use on whatever upgraded equipment I purchase and maybe my old fish tank thermometers from Walmart that are probably 4 years past their usable limit. I generally run ice water cal checks on my thermometers every year and toss those that perform poorly, but this has the distinct disadvantage of not being within the range of its use temperature and I've noted significant sensitivity drift between 32*F and 100*F so I'm hesitant to incubate based on shoddy quality control practices.

Fair warning - any attempt to convince me that hens don't bother with this and thus I should not either will fall on deaf ears.

 

[raingarden]

I use medical digital thermometers. They have a narrow range which includes the 99.5 to 100.5F needed for hatching. The narrower the range, the easier it is for the manufacturer to make them accurate. One would think that since they are made to detect a fever and protect human health they would have to be very accurate. The truth is they can vary by up to one degree F. Because of the narrow range they cannot be calibrated with ice water and boiling water like a wide range instrument can..

So, I've accumulated four digital thermometer. I measured my own temperature under the tongue with each of the thermometers and recorded the readings. The one that gave me the median or closest to the average reading is the one I use for incubation.

No, I'm still not satisfied but that's the best I can do without forking over the big bucks for a certified mercury thermometer.

 

[Karasu]

I use medical digital thermometers. They have a narrow range which includes the 99.5 to 100.5F needed for hatching. The narrower the range, the easier it is for the manufacturer to make them accurate. One would think that since they are made to detect a fever and protect human health they would have to be very accurate. The truth is they can vary by up to one degree F. Because of the narrow range they cannot be calibrated with ice water and boiling water like a wide range instrument can..

So, I've accumulated four digital thermometer. I measured my own temperature under the tongue with each of the thermometers and recorded the readings. The one that gave me the median or closest to the average reading is the one I use for incubation.

No, I'm still not satisfied but that's the best I can do without forking over the big bucks for a certified mercury thermometer.

That's a good low-budget way to approach the issue. Have you been able to find medical thermometers that provide a constant reading rather than requiring a push-button use? That was my first plan, but the available spread of medical thermometers on Amazon was rather lacking.

 

[raingarden]

That's a good low-budget way to approach the issue. Have you been able to find medical thermometers that provide a constant reading rather than requiring a push-button use?

No. The digital ones will read until the auto shut-off kicks in. The old style mercury medical thermometers only go up so the reading does not fall after removing it from the mouth or rectum. After reading you have to shake the mercury back down.

I also have some cheap digital thermometers with a probe wire. They're worth what I paid for them but they do provide a constant reading.

Who would have thought that somethng so simple would be so difficult.

 

[Karasu]

No. The digital ones will read until the auto shut-off kicks in. The old style mercury medical thermometers only go up so the reading does not fall after removing it from the mouth or rectum. After reading you have to shake the mercury back down.

I also have some cheap digital thermometers with a probe wire. They're worth what I paid for them but they do provide a constant reading.

Who would have thought that somethng so simple would be so difficult.

That does seem like a drawback but the narrow range is certainly appealing. I'll order the probe thermocouple soon and see how well it works after calibration.