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 Mklangelo
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Registered: 10/30/01
Posts: 297
Loc: Continental United States
Last seen: 22 years, 10 months
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 Calibration of Analog Hygrometer... 
#459555 - 11/15/01 04:53 PM (23 years, 1 month ago) |
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I have me here one of these "Cigar Perfect" Rh meters. I saw this method of calibration where you take a few drops of water in a tsp of salt inside a jar lid, put it and your meter in a tupperware, wait 6 hrs and calibrate to "EXACTLY" 75%. I've done this 3 (three) times and my readings vary by as much as 8 points. I am operating under the assumption that "a few" drops of water means three. If the guy means three, why don't he just say so for cryin out loud. Who writes this shit anyhow?
So in other words, did I waste $14.00 US on the meter or what?
thanks ;-)
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[red] Life:[/red][blue] Live it foward, understand it backward...[/blue]
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 Hippie3
mycotopiate
Registered: 11/06/99
Posts: 3,090
Loc: mycotopia.net
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 Re: Calibration of Analog Hygrometer... [Re: Mklangelo]
#460167 - 11/16/01 05:39 AM (23 years, 1 month ago) |
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most of those cheap ones are utter crap.
cool zappa quote, btw.
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Insomnia
addict
Registered: 07/17/00
Posts: 345
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Re: Calibration of Analog Hygrometer... [Re: Mklangelo]
#460178 - 11/16/01 06:08 AM (23 years, 1 month ago) |
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The easiest way to calibrate those types is to soak a paper towel, wrap the meter in it, wait a few, then set it to 75. If you do that and it still gives you a headache, do it again, and try setting it to 95 or 100.
Those RH meters are a pain.
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"If you believe in things you do not understand, you will suffer." ? Stevie Wonder
Edited by Insomnia (11/16/01 06:08 AM)
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Anno
Experimenter
Registered: 06/17/99
Posts: 24,167
Loc: my room
Last seen: 1 month, 3 days
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Re: Calibration of Analog Hygrometer... [Re: Mklangelo]
#460179 - 11/16/01 06:08 AM (23 years, 1 month ago) |
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The goal is to obtain a saturated salt solution. this means there should be some sole and still some salt in cristal form present. that?s why it says a few drops of water, just to make sure that you don?t use mainly water with a spoon of salt in it.
This method works. I calibrated and tested several hygrometers. (cheap and more expensive). 14$ is not that cheap.
>If the guy means three, why don't he just say so for cryin out loud.
Just make the salt realy wet.
>Who writes this shit anyhow?
There original document can be found here:
http://www.bcspecialties.com/cigarasp/hygcal.asp
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Anno
Experimenter
Registered: 06/17/99
Posts: 24,167
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Re: Calibration of Analog Hygrometer... [Re: Insomnia]
#460180 - 11/16/01 06:10 AM (23 years, 1 month ago) |
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>The easiest way to calibrate those types is to soak a paper
>towel, wrap the meter in it, wait a few, then set it to 75.
?????? ! ! ! ! ! !
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Insomnia
addict
Registered: 07/17/00
Posts: 345
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Re: Calibration of Analog Hygrometer... [Re: Anno]
#460187 - 11/16/01 06:19 AM (23 years, 1 month ago) |
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Heh -- what's that, now? I just meant that you can use a soaked paper towel, rather than fussing with containers, wet salt, and so on.
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"If you believe in things you do not understand, you will suffer." ? Stevie Wonder
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CoolMojo
Imagination iswhat you make ofit
Registered: 10/26/01
Posts: 334
Last seen: 5 years, 7 months
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Re: Calibration of Analog Hygrometer... [Re: Insomnia]
#460199 - 11/16/01 06:50 AM (23 years, 1 month ago) |
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While I'm no shroom growing expert, I do know my way around a humidor. Use any bottle cap, fill full of salt and add JUST enough water to wet the salt and still have just a tiny bit of crystals left. Use a ziplock baggie (there is to little water to use most tupperware dished) seal the bottle cap and the hygrometer in a baggie leaving the bag only half full of air and wait a few hours. The salt prevents the water from evaperating if the surounding humidity is any more then 75%. Its a VERY reliable method of calibration.
As for the price of the hygrometer....most don't last very long and the problem is there pretty much all the same until you get up there in price. $14 or $40, either way your pretty much buying the same item.
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Anno
Experimenter
Registered: 06/17/99
Posts: 24,167
Loc: my room
Last seen: 1 month, 3 days
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Re: Calibration of Analog Hygrometer... [Re: Insomnia]
#460315 - 11/16/01 10:00 AM (23 years, 1 month ago) |
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Insomnia, the whole point in using a saturated salt solution in your sealed container is that this has a defined equilibrium point at 75% RH at the room temperature. Different salts will give you diferent humidity levels.
You can?t simply take a wet towel and expect it to do the same job.
I think you need to reed a bit further:
http://www.omega.com/temperature/Z/pdf/z103.pdf
http://lists.dalsemi.com/maillists/weather/2000-October/002299.html
http://www.vaisala.com/DynaGen_Attachments/Att4355/4355.pdf
http://fscn1.fsci.umn.edu/ted_Labuza/awimages/Salt%20solutions%20FOR%20Isotherm.pdf
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Mklangelo
enthusiast
Registered: 10/30/01
Posts: 297
Loc: Continental United States
Last seen: 22 years, 10 months
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Re: Calibration of Analog Hygrometer... [Re: Anno]
#460478 - 11/16/01 12:42 PM (23 years, 1 month ago) |
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I bow before the Relative Humidity master! Thanks alot. I'll redo it since I now have more detailed info. Nothing is too good for my little Cambodian Cuties....
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[red] Life:[/red][blue] Live it foward, understand it backward...[/blue]
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