Hygrometers, hygrometers, hygrometers, oh my!

Ginseng

Banned
I've been using a mish mash of hygrometers from various vendors over the years. Enough is enough. I finally decided to come into the 21st century and go wireless. Why? because you don't have to keep opening your coolers or cabinets to check the conditions. You can verify the humidity and temperature in all your storage systems as easy as pushing a button at your desk.

Of course, all this technology is useless unless you know how accurate your units are so conducting a periodic (every 6 months) salt test is something I consider absolutely essential. Even if you have the best of technology...trust but verify.

One unit that I've used for several years is a now-discontinued hygro from RadioShack. Small, cheap, reasonably accurate; it is perfect for small containers. It has held steady at a -3 offset the entire time I've owned it. This unit is a bargain at under $20. Uniquely, it uses two button cells in parallel for extra long operation on a set of batteries.

I should mention that a NEGATIVE offset as I define it means the hygro reads LOW. That is, if the salt test target is 75% the RadioShack unit would read 72%. Likewise, a POSITIVE offset means the hygro reads HIGH: 78% when actual is 75%.

About a year and a half ago, I bought two units from Little Havana Cigar Cigars. Primarily this was based on the many positive recommendations that turned up in searches in this sub-forum. Unfortunately, the units I received registered RH that was far from actual. The initial calibrations showed +6 and +7 on the two units. Over the time I've had them, the readings have drifted to +7 and +8, respectively. This should be considered unacceptable and I should have returned the units. You can find this hygro here. This potential drift is one reason why periodic calibrations are so important to give you confidence in the readings from your device.

Most recently, I purchase a three-channel Oregon Scientific wireless weather station from Mark Neff at Cigarmony. His prices on this unit were about the best I could find but what really sealed the deal was the special 2-pack sensor special that you could buy with the weather station (which already came with 1 sensor). This was a stroke of genius as it makes perfect sense that a person buying a 3-channel station might want two more sensors to maximize the potential of the system. Kudos to Mark. You can find this unit here. I also purchased an additional adjustable digital hyrgrometer but that unit was defective and Mark is taking care of that for me right now.

Here is a photo of all my operational hygrometers. The Oregon Scientific base station is at the back. This unit is super cool. It even tells me the time and date by jacking into the signal from the atomic clock in Colorado. It is also smart enough to forecast weather based on the barometric reading and to calculate the moon phase from the built-in calendar. Very smart. Note that for easy reference, I have labeled the base unit and the remote units with the offset and the target reading. These three sensors were pretty darn close to target with one at zero offset, one at -1 and one at +2. I'd consider this acceptable. The smaller unit on the right is the THGR122N sensor that came with the base station and the two larger ones on the left are the new THGR268 sensors from the Cigarmony 2-pack. The new units are identical in operation as far as I can tell but with the added convenience of a larger display and a battery door that does not require a screwdriver to open. (Note: sharp eyes will notice that OS hygrometer #3 is labeled "+2 67" instead of "+2 69" as it should be. I've corrected that on the unit but sure as heck am not going to go drag all the hygros out for another family picture. (IMG:style_emoticons/default/tongue.gif) )
(IMG:http://i61.photobucket.com/albums/h73/Gins...Hygrometers.jpg)

Here is a photo of my hygrometer calibration box. It is a thick-walled, gasketed unit from Lock&Lock. You can find these fantastic boxes at Target. I consider them superior in overall design to the venerable Rubbermaid snap-top containers. Since I have so many hygros, it would have been inefficient to use the small plastic bags that came with the one-step calibration kits from Mark. In fact, the new THGR268 sensors just fit into the bags, but it's too tight for my comfort. I bought two calibration kits just to check my salt setup and ended up using both the calibration pillows along with a dish of salt solution of my own. I also checked this calibration at two temperatures, 60F and 70F and across that range, the measured relative humidity did not change at all for any of the hygrometers. This result gives me the confidence that within the range of temperatures that my storage containers experience, the readings will be accurate and reliable.
(IMG:http://i61.photobucket.com/albums/h73/Gins...HygroCalBox.jpg)

Here is a close-up of my salt slurry dish. Keep in mind that the science says that 75% is achieved by using a saturated solution. In my experience, a wet slush like this gives more reliable results than a slurry that appears dry. I like there to be a layer of liquid at the top of the dish.
(IMG:http://i61.photobucket.com/albums/h73/Gins...CalSaltDish.jpg)

And that's pretty much it. I am really loving the OS weather station and the ease and peace of mind it provides. I suspect it won't be long before I spring for another base station and additional sensors. This thing is just too damned good not to have watching over my cigar collection.

Wilkey

PS. I use self-conditioned silica crystal kitty litter and/or propylene glycol water solution to manage the humidity in my coolers.

Edit: Whenever I changed conditions in the calibration box (added hygros, moved from higher to lower temperature conditions) I gave the system 24 hours to equilibrate. Typically the readings would adjust and stabilize quite quickly over the course of an hour or two but I wanted to make sure the flatline-unchanging readings really were stable. You don't really want to rush things but this suggests that an impermeable container (such as tomato sauce jars I've used in the past), ones with tight seals and/or thick walls will allow conditions to stabilize quickly and well. This is what you want when assessing an equilibrium condition. Single layer ziplocs are not, in my opinion, optimal.
 

Infinity

Infinity - *Unbounded space, time, or quantity*
I have the Oregon units, I use them in my two large humidors, they are great.

Hey Wilkey, can I send my units to you for testing, holy crap, that is one interesting setup. Mind you, shipping back and
forth may throw them out, so what's the point :sign:

Brian
 

Ginseng

Banned
Thanks, Wilkey, especially for the clairifcation on saturated solution.
No prob, Bruce. Although you probably know that the strict definition of a saturated solution means that solid and liquid phases are in equlibrium. The solution should be clear but contain enough salt so that even one more grain will not dissolve. Here we have quite a large reservoir of undissolved salt. Practically speaking, though, as long as there is a solution phase above the salt and all the rest of the materials in the calibration box do not contribute to either the uptake or release of moisture, this should work fine. I think. ;)

Wilkey
 

enerjay

Active Member
Thanks, Wilkey, especially for the clairifcation on saturated solution.
No prob, Bruce. Although you probably know that the strict definition of a saturated solution means that solid and liquid phases are in equlibrium. The solution should be clear but contain enough salt so that even one more grain will not dissolve. Here we have quite a large reservoir of undissolved salt. Practically speaking, though, as long as there is a solution phase above the salt and all the rest of the materials in the calibration box do not contribute to either the uptake or release of moisture, this should work fine. I think. ;)

Wilkey
A quote "An empirical approach is a worthy and pragmatic approach"

You said it. :D

yes I had to look the words up. :sign:
 

Ginseng

Banned
I have the Oregon units, I use them in my two large humidors, they are great.

Hey Wilkey, can I send my units to you for testing, holy crap, that is one interesting setup. Mind you, shipping back and
forth may throw them out, so what's the point :sign:

Brian
Brian,

If you'd like me to calibrate your hygros, send 'em on over.

Wilkey

PS. I just realized that since these are 3-channel units, it might well be impossible to have two base stations each with three sensors in the same house.
 
The pic of your slurry alone is worth the price of this post Wilkey. It seems often there's questions about how wet the slurry should be. Agreed with the first poster that this should be pinned. VERY nice writeup!
 

Ginseng

Banned
Thanks, Wilkey, especially for the clairifcation on saturated solution.
No prob, Bruce. Although you probably know that the strict definition of a saturated solution means that solid and liquid phases are in equlibrium. The solution should be clear but contain enough salt so that even one more grain will not dissolve. Here we have quite a large reservoir of undissolved salt. Practically speaking, though, as long as there is a solution phase above the salt and all the rest of the materials in the calibration box do not contribute to either the uptake or release of moisture, this should work fine. I think. ;)

Wilkey
A quote "An empirical approach is a worthy and pragmatic approach"

You said it. :D

yes I had to look the words up. :sign:
My my, I've been caught out! :blush:

What's your handle over there, Jay?

Wilkey
 

enerjay

Active Member
Thanks, Wilkey, especially for the clairifcation on saturated solution.
No prob, Bruce. Although you probably know that the strict definition of a saturated solution means that solid and liquid phases are in equlibrium. The solution should be clear but contain enough salt so that even one more grain will not dissolve. Here we have quite a large reservoir of undissolved salt. Practically speaking, though, as long as there is a solution phase above the salt and all the rest of the materials in the calibration box do not contribute to either the uptake or release of moisture, this should work fine. I think. ;)

Wilkey
A quote "An empirical approach is a worthy and pragmatic approach"

You said it. :D

yes I had to look the words up. :sign:
My my, I've been caught out! :blush:

What's your handle over there, Jay?

Wilkey
Its bachelor, however Kirk (MMM) explained to me that changing your handle between boards is not recommended. Still waiting for the boys to let me in. LOL
Wilkey
 

anvil

Distant Member
Good post mate
I was way of when I performed my first salt test, I will try again on reading this.
Thanks mate :D
 

jfields

Where did all my money go?
Wow! Now you have me wondering, how reliable is my digital hygrometer? I would be interested to know how you are coming up with the variables on the two from salt test to coolidor? Why is it changing or, am I just not understanding your last post?

Thanks for this piece Wilkey. I have never been too sure on how moist the salt solutin should be when doing the test. I have also wanted to do a wireless type station like I have set up for outside and, the childrens rooms (wife is overprotective.....just a tad :rolleyes: ). I have never been able to find one that also does humidity with the remotes until this post of yours..........Thanks,

John
 

Ginseng

Banned
John,

I am assuming that the Boveda kit is giving me 75% as advertised. I also gather that my coolidor is at a "different" humidity although now I am not sure exactly what. For purposes of comparison, I then regard the Cigarmony unit as "correct" at both conditions. This then provides the baseline against which another hygrometer can be compared.

What would be ideal would be to calibrate a hygrometer at two different, known humidities. This would give you the slope of the line of "indicated" against "true" humidity which should be 1.0. In the above case, the slope of the LittleHavana unit is greater than 1.0 which is not good.

Wlkey
 

smellysell

Go Vols!!!
I could very well be wrong Wilkey, but would the logical next step be to salt test all your hygros (which I believe you have already done), then put them all in the same humi and see what the results are?
 

jfields

Where did all my money go?
John,

I am assuming that the Boveda kit is giving me 75% as advertised. I also gather that my coolidor is at a "different" humidity although now I am not sure exactly what. For purposes of comparison, I then regard the Cigarmony unit as "correct" at both conditions. This then provides the baseline against which another hygrometer can be compared.

What would be ideal would be to calibrate a hygrometer at two different, known humidities. This would give you the slope of the line of "indicated" against "true" humidity which should be 1.0. In the above case, the slope of the LittleHavana unit is greater than 1.0 which is not good.

Wlkey
I understood the difference between the humidity of the salt test and what was the actual level of the coolidor. What I did not understand was how you could go from a 7% difference between the two on salt test and, what was a 3% difference (right?) between the two in the coolidor right after calibrating. That is pretty significant it seems. Maybe the little Havana is just defect.
 
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