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Last post 12 months ago by tonygraz. 18 replies replies.
Calibrating a digital Hygrometer
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gtrkc Offline
#1 Posted: Tue, Mar 13 2007, 6:30 AM EST
Joined: 12-25-2006
Posts: 9
What is the best way to calibrate a digital hygrometer?
ARN Offline
#2 Posted: Tue, Mar 13 2007, 6:35 AM EST
Joined: 10-14-2005
Posts: 11,393
Go to advanced search and look up salt test. There is a lot of good info already out there.
serion Offline
#3 Posted: Tue, Mar 13 2007, 6:53 AM EST
Joined: 03-09-2007
Posts: 177
As recommended look up the salt test.

Not to hijack the thread but I thought this might be a valid question.

I did the salt test with my digital hydrometer. After 8 hours it read that my hydrometer was off by -2. After 16 hours it read -2 and at 24 hours it was still off by -2. I forgot about it and after 3-4 days it read that it was off by +15. By this point the salt paste had started to harden and dry up. Is the -2 reading correct or should I be looking for a new digital hydrometer? I did the test in a clear plastic rubbermaid container which seals air tight with a constant room temperature of 68 degrees.
JHC Offline
#4 Posted: Tue, Mar 13 2007, 6:56 AM EST
Joined: 12-27-2005
Posts: 19,283
Are you saying that it read 90 % ?
serion Offline
#5 Posted: Tue, Mar 13 2007, 6:57 AM EST
Joined: 03-09-2007
Posts: 177
Yes, after 3-4 days it ready 90%

The initial readings after 8, 16, and 24 hours read 73%
andytv Offline
#6 Posted: Tue, Mar 13 2007, 7:12 AM EST
Joined: 10-23-2002
Posts: 40,991
I don't know if this applies or not, but the cheap digitals you get at that big "W" store for about $6 DO NOT WORK.

I had three in the same container for a test and there were over 15% points of error between them.
serion Offline
#7 Posted: Tue, Mar 13 2007, 7:32 AM EST
Joined: 03-09-2007
Posts: 177
Mine did happen to come from the big "W". It wasn't originally purchased to be used with my humidor so if its crap its not a big deal I'll just look for a good one to go in the humidor.
JTokash Offline
#8 Posted: Tue, Mar 13 2007, 8:38 AM EST
Joined: 02-12-2007
Posts: 5,234
A while ago I read somewhere that the salt test actually screws up a digital hygrometer somehow. I'm not sure what the reason was... I was probably reading the article late at night. Has anyone else heard of that?

I calibrated an analog hygrometer with the salt test, then took my digital and put it side by side to the calibrated analog hygrometer and took it into the bathroom, started the shower just to make a lot of steam and as the analog went up, the digital one followed almost perfectly (probably within 1-2% at all times). It worked for me, but I did it that way because I read that article about salt tests being bad on digital hygrometers.

Regards,
-JT
daveincincy Offline
#9 Posted: Tue, Mar 13 2007, 8:39 AM EST
Joined: 08-11-2006
Posts: 20,033
My digital specifically stated in the instructions NOT to do a salt test on it, and that it was calibrated from the factory. Supwitdat? After doing any salt tests with some analog hygrometers, I've used the digital in conjunction with the analog in a humi just to see how the analog reads vs. the digital. Actually, I still do this often just to check the analogs since they're crap to begin with.
Slimboli Offline
#10 Posted: Tue, Mar 13 2007, 9:25 AM EST
Joined: 07-09-2000
Posts: 16,139
Digital hygrometers CANNOT be calibrated ...

... only checked to see where it reads (when it should be 75%), then +/- will give you the accurate reading of the Rh in your humidor.
daveincincy Offline
#11 Posted: Tue, Mar 13 2007, 9:41 AM EST
Joined: 08-11-2006
Posts: 20,033
Good point Slim. There is a difference between calibrating and just checking for accuracy. The only way I know to calibrate a digital is test for accuracy via salt test, and if it's off too much I use a 5lb hammer to dial it in.
bsevern Offline
#12 Posted: Tue, Mar 13 2007, 9:41 AM EST
Joined: 07-24-2006
Posts: 8,062
Actually there are a couple of digital hygrometers that can be calibrated.

For example:

The HygroSet II is the first digital hygrometer of its kind capable of being adjusted after calibration. Each click of the adjustment knob changes the humidity display (+ / -) by 1%.
[email protected] Offline
#13 Posted: Wed, May 17 2023, 4:25 PM EST
Joined: 01-19-2023
Posts: 25
...so more on this...

I just bought a Cigar Oasis Caliber IV hygrometer. Supposed to be pretty good (and can be calibrated). Its got some cool features such as recalling a 3 day average humidity. Its supposed to come calibrated from the factory ±1%. Naturally I want to verify this, and I usually do the salt test but was thinking of other ways to do it. My digital humi-care hygrometer is off like 4% and it, well, to say the least - scares me. I mean, it doesn't seem too much to ask to have it read the exact humidity ±1%. I thought of buying a Boveda one-step calibration kit but that kinda seems like a waste when I think of it like this:

Why not just put a 69% Boveda pack in a ziplock bag with my new hygrometer for a day or so? No one mentions using a Boveda pack to check a hygrometer's accuracy. IDK if its just because they're relatively new or if there's some unforeseen (to me) reason it won't work.

I just ordered it today so it won't arrive till Monday.

Thoughts?
Stogie1020 Offline
#14 Posted: Wed, May 17 2023, 5:38 PM EST
Joined: 12-19-2019
Posts: 5,350
[email protected] wrote:
...so more on this...

I just bought a Cigar Oasis Caliber IV hygrometer. Supposed to be pretty good (and can be calibrated). Its got some cool features such as recalling a 3 day average humidity. Its supposed to come calibrated from the factory ±1%. Naturally I want to verify this, and I usually do the salt test but was thinking of other ways to do it. My digital humi-care hygrometer is off like 4% and it, well, to say the least - scares me. I mean, it doesn't seem too much to ask to have it read the exact humidity ±1%. I thought of buying a Boveda one-step calibration kit but that kinda seems like a waste when I think of it like this:

Why not just put a 69% Boveda pack in a ziplock bag with my new hygrometer for a day or so? No one mentions using a Boveda pack to check a hygrometer's accuracy. IDK if its just because they're relatively new or if there's some unforeseen (to me) reason it won't work.

I just ordered it today so it won't arrive till Monday.

Thoughts?

Here, I looked it up for your lazy arse... https://bovedainc.com/question/can-i-calibrate-my-hygrometer-using-any-rh-boveda/

You're welcome.
[email protected] Offline
#15 Posted: Wed, May 17 2023, 7:00 PM EST
Joined: 01-19-2023
Posts: 25
Hey, at least I searched the forums...lol

and thank you Stogie.... so yes, the way I read that article, one can calibrate a hygrometer using a 69% Boveda pack.

I'll crawl back under my rock now Frying pan BigGrin
Stogie1020 Offline
#16 Posted: Wed, May 17 2023, 7:03 PM EST
Joined: 12-19-2019
Posts: 5,350
[email protected] wrote:
Hey, at least I searched the forums...lol

and thank you Stogie.... so yes, the way I read that article, one can calibrate a hygrometer using a 69% Boveda pack.

I'll crawl back under my rock now Frying pan BigGrin

lol, but it will be +- 2.00%. Whereas the calibration boveda is +- 0.03%.
Doesn't 1.97% matter to you? I mean, what kind of person are you, really?
LeeBot Offline
#17 Posted: Wed, May 17 2023, 10:55 PM EST
Joined: 07-08-2020
Posts: 2,017
If it's 1.97% off, does that mean it's 98.2% accurate?
tonygraz Offline
#18 Posted: Thu, May 18 2023, 6:37 AM EST
Joined: 08-11-2008
Posts: 20,273
If you concerned about humidity being 1.97% off, chances are that you are 98.2 % off.
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