Temperature Accuracy & its Effect on the RH% readout

[BarryNY]

Some of you here are wayyyy more experienced than I am with regards to CC and storage methodology.  But I may have stumbled onto something that you guys already know or have ignored like I have been ignoring.....

I have been diligently trying to calibrate my wireless hydrometers to make sure that all readings are consistent/accurate.  I laid them all out on my table and the readouts varied from temperatures of 71 to 73 degrees and RH% of 48 to 55%.  I thought OK - they are all within the parameters of the accuracy specs so I set about looking to calibrate each one's RH% individually.

My first mistake was trying to calibrate them to a Boveda 75% pack.  Why is that the recommended standard for calibration if we want our hydrometers to be perfect in a 65% or 68% RH environment?  Yesterday I ordered the 65% pack as that's where I want my newair to be so I'm going to calibrate to that environment.

Additionally, I think most fail to recognize the profound effect that temperature plays on the calculation of the RH% that our little hydrometer makes.  Textbook definition of RH% is:

Relative humidity is the ratio of the partial pressure of water vapor (WV) to the equilibrium vapor pressure (EVP) of water at a given temperature.  Relative humidity depends on temperature of the system of interest.

So, our hydrometers are doing a quick little calculation in order to display the RH%.  They are taking the reading of WV present in the humidor/winedor and also taking the reading of the temperature in the humidor/winedor and coming up with the ratio calculation.  The denominator in the equation, the EVP, is fixed and known at every temperature.  So for instance, if the sensor reading for the WV is 17 and the temperature is 70 degrees (a 25.0 EVP) then the RH% is calculated as 17/25 or 68%.  With the same sensor reading for WV of 17 but with a BAD temperature reading of 68 degrees (a 23.4 EVP), the RH% will now show 72.7% because the equation is 17/23.4.  A 2 degree difference in the temperature that your hydrometer is picking up will cause a 5.7% difference in the RH% that it shows....or approximately a 3% swing for every degree F in temperature that the hydrometer is off.  

I now believe the temperature is the most important element we need to make sure is perfect, then you can make a better calibration of the RH% after letting the hydrometer sit with the Boveda pack for the day or two.  I'll be experimenting more when my 65% packs arrive...

Please chime in if I'm a complete offbase arsehole or this is truly something we need to be aware of........

 

 

[CaptainQuintero]

It's certainly something that you can get lost down the rabbit hole with.

In my first few years I let it get to me far too much and the stress stopped me from enjoying the whole thing! Like you say even calibrating can bring on a whole new sack of stresses.

In the end I just keep a few hygrometers around just to see what general Rh I'm in (60s) and rely on how the cigars feel to my touch. I've enough beads etc to sink a battleship, they are not all clear and not all white, so I'm somewhere near the advertised Rh ish...

The beads look ok, the cigars have a definite dry crackle to the squeeze, I'll leave it until one of those two changes.

But that's just me, if you like and enjoy the aspects of heavy monitoring and in depth controls there is more then enough to have fun with, but that level of expertise is beyond me but definitely within the scope of others on here.

If you do a search for humidity and pigfish then you did get a lot of research and discussion pop up to keep you occupied for days if not weeks

[stogieluver]

Paging Mr. Piggy.  Paging Mr. Piggy.  You two will make a lovely couple.   

[JohnS]

2 hours ago, stogieluver said:

Paging Mr. Piggy.  Paging Mr. Piggy.  You two will make a lovely couple.   

Don't forget the Goo or NSX! 

[trike]

Anyone see the movie Groundhog's Day.? This thread reminds me of that movie. 

I feel the responses being prepared. 

[BarryNY]

9 hours ago, Hutch said:

My head hurts when I try to do the math. I enjoy my cigars, given a fairly constant 75F at 61-63%RH. How would this equate at 70F and 80F ? TIA

75F has an EVP of 29.6.  If you are averaging 62%RH at 75F then your environment has a WV of 18.3.  18.3/29.6 = 61.8%RH.

If the space was sealed tight, and all you did was lower the temp to 70F (which has a 25 EVP) the reading on your hydrostat should go UP to around 73.2%RH.

At 80F (which has approx an 33.5 EVP) the reading should go DOWN to around 54.6%RH.

[scap99]

Duct tape your head so it doesn't explode before you read this....

 

Barometric pressure/elevation affects water vapor pressure, too.

 

[Pedgy]

How about 68 degrees and my RH is sitting at 62/63.  Thank you

[BarryNY]

20 minutes ago, Pedgy said:

How about 68 degrees and my RH is sitting at 62/63.  Thank you

OK - you guys can break my balls all you want...I was born in Brooklyn, NY - I can handle all the sh-t you can throw at me LOL.....here's the last Mr. Math for the post:

Pedgy: The WV (water vapor) would be about 14.6 for you to get a 62.3%RH reading @ 68F.

Below are EVP extrapolations for you to do the math...but quick rule of thumb is about a 3%RH swing for every 1F change/error in your temp.

To figure out approx how much WV is in your container environment, use the below number and multiply it by the %RH you are showing then move the temps around and see the effect.  I would confirm the temperature of my hydrometer before doing any %RH calibrations.

65F = 21.0; 66F = 21.8; 67F = 22.6; 68F = 23.4; 69F = 24.2; 70F = 25.0; 75F = 29.6

Watch those coolidors....don't let them get too hot or your RH% is gonna drop like a rock....going from 72F to 75F loses about 8%RH!  In the hot weather check your RH% often...or get a wireless temp/RH transmitter so you don't have to open the door too much...

[Pedgy]

Thanks BARRY.  I appreciate it and sorry for busting balls. 

[BarryNY]

44 minutes ago, Pedgy said:

Thanks BARRY.  I appreciate it and sorry for busting balls. 

Ok....no problem and you didn't bust anything............if your temp is correct - you are looking purdy.......real purdy!

[Fugu]

Haha, guys, we can actually keep it very simple here: The sensor "senses" relative humidity directly. No need to do any calculation and bother with temperature by yourself.

The instrument's (hygrometer) rH-sensing element (in the type you are supposedly using) is utilizing a hygroscopic dielectricum in a capacitor, i.e. electr. capacity changes with rH and that will be sensed directly. There is of course a specific thermal coefficient for the sensor, but these bulk produced sensors are already precompensated with regard to the Tc, irrespective of the actual temperature reading (or off-reading ) of your device.

So, in a nutshell, you guys don't have to bother with temperature (yourself) when dealing with the rH-reading.

Caveat: But what you need to observe painstakingly during calibration, is to get into a thermal equilibrium. I.e. make sure that temp is kept absolutely stable during calibration, since short-term temp fluctuations will lead to variations in actual rH and also in rH-reading. But that's really all you need to know and do.

Take your not too tiny 65%-Boveda pack (who sais 75% being "the" standard? Even better would be a 2-pt calib) toss into a tupperbox with your instrument to calibrate and read after a 2-3 hour, or longer if necessary, stabilization and equilibration time (the Boveda will have to be given enough time to saturate the atmosphere in the test chamber - just take repeated readings until stable).

[BarryNY]

Ok - I think I get what you are saying.  How would we account/calibrate for the following:

2 identical sensors inserted into the tupperbox with a 65% Boveda....after 24 hours:

sensor A reads 72.5F and shows 62%RH and sensor B reads 71.0F and shows 66%RH - what calibration adjustments would you make for each one to be spot on?

[Fugu]

Ignore the temperature reading for your rH calibration. There will of course be a residual temp-error in each sensor but you won't be able to calibrate that (with your means, I suppose), and it is not of major relevance to us anyway. And - that Tc is not being represented by the actual temperature reading - or error thereof - on display! Just calibrate @ or close to storage temperature and you'll be fine. Take a note or even make a regression for the rH-slope and -offset correction and that's it. As long as doing a one-point calibration, sensor temperature coeff is the least you have to bother about anyway.

[BarryNY]

OK thanks.  I will be doing the calibration with the tupperware inside the winedor at 65F.

[Fugu]

1 hour ago, BarryNY said:

OK thanks.  I will be doing the calibration with the tupperware inside the winedor at 65F.

Yep, that would be the best to do - provided temp.-circling is of shallow amplitude (... see Mr. PigFish on humidor controlling for some 'digest' ....  ). Otherwise, a stable room temperature on an appropriate day might do as well.

[CaptainQuintero]

Re the kits, I think the 75% calibration kits are around because the older style hygrometers from calibre etc would only recalibrate to 75%and no other value. There wasn't the ability to adjust the calibration until the newer models of 'cigar hygrometers' were released a few years ago

 

[PigFish]

14 hours ago, stogieluver said:

Paging Mr. Piggy.  Paging Mr. Piggy.  You two will make a lovely couple.   

-LOL

My friend Barry here has already got my email going on the subject... 

Gooey here is right on the button. What has been assumed is that the temperature that one reads in a sensor is what is being used to calculate rH. What one needs to know then is the architecture of the rH sensor. I believe that The Goo has covered that.

One should understand that rH sensors are made to be 'stand alone.' The architecture therefore is not dependent on what you read off the thermometer. Now of course certain makers could be different. I don't claim to know the architecture of every sensor. But I do believe that it is safe to assume that Gooey is correct here. I do... I would never attempt to recalculate for rH based on yet another calculation. Simply put, if you want your rH sensor calibrated, take it to a calibration house and have it professionally done if you are really that hung up about it.

This comes back to a broader question, yet again about 'accuracy.'

From my perspective there is the science, the experience and the taste.

Gooey and I recently had an interesting interaction about accuracy of equipment. I think it might have surprised him some, that a guy (like me) who sells this stuff, would tend to 'boohoo' instrument accuracy. Now mates, I am not against it, but I understand it. Accuracy can be expensive and while it is a useful tool, in some ways it is only a language that we share. He made a point about accuracy (long term) and sensor creep. Of course that was astute and correct, yet creep is an argument about then the period of sensor calibration.

So, if in a broad sense, rH calibration is a means to communicate rH, a language, what is the language worth to you? That is the question I always ask.

This is why I tend to rely mostly on the smoking experience as a judgement of my instrumentation. Yes, my settings mean something to me, but in the vast internet world, when I post 60/70... does it come with a NIST cert? Do I post a cert with each post? No it does not and no I do not. As a guy that is represented by pixels on a flat screen, I could be totally FoS (Full of....). It is why I give advice, but never make unreasonable demands to emulate me, nor anyone else. There is no right and wrong (beyond the the limits that represent the destruction of the media) with or without water. There is then a starting point and then experience and taste.

You don't know if my instruments are accurate or not really, now do you? Because I claim to be an authority on the subject, many simply assume me to be! That is the power of the internet! It is why I always ask. How do the cigars smoke and taste? Smoke and taste "are" the only legitimate measures (IMHO). The instruments, whether they be $2.00 or $2000.00 are just a guide. AND it is damn certain, they don't measure taste!

What matters in this debate? The guy with the most expensive (presumed accurate) sensor??? Hardly! What matters is satisfaction and understanding cigar condition with real life experience. Yes, you need an instrument, yes it is nice if it is accurate, no it is not worth any amount of money and trouble. The fact is, I am pretty good at this, and I cannot tell 1 or 2 rH. Can you?

From my end, the ability to control is worth more than the ability to be accurate to a national standard. The ability to predict, to diagnose and evaluate, those are worth more to me than a NIST cert. Yes, the ability to control is also linked to accuracy. But even the most accurate sensors have and error. Where then does this end?

That is my philosophy and I am a guy who owns some sensors with NIST certs. What good do they do me really? It is shit to brag about in the right circles (I guess). That is if anyone cares. I don't... 

What matters to me is that I can help people diagnose humidor problems and get some (not all) on a line to a simple solution. When a guy writes me and says, "Hey Ray, thanks for spending the time, you really helped me out." Damn... That means something to me! Whether his sensor agrees with mine, a language problem, does not enter into the conversation. When one understands that taste is about opinion, one suddenly realizes that sensor accuracy for a great many people becomes lesser important. Perhaps it is more important to a guy like me who can control my humidor, up, down, right and left... But given the limited range of control that most possess and need, I ask you, do you need to have the most accurate instruments? I mean if you are storing at 63rH and have the desire, but not the means to move the entire contents of the humidor 62.4rH, what really is the point?

You don't need a certified sensor to get a good cigar. That is the lesson that I try to impart. Yes we can argue that attributes and values. But where does that get you? Wiser, maybe... But if it causes undue consternation about your storage, then it is better left unread! (MHO)

And Barry, what is perfect? You see that is the hitch. Perfection and satisfaction are not the same. Perfection may be a goal for a 'hung-up' guy like me and maybe it is right for you. My advice, pursue satisfaction instead. It is far cheaper and far more rewarding. For me storing cigars is as much about a philosophical outlook as a scientific one, even though I am rather obsessed with the science and the results of using it. When said and done I must answer a call for pragmatism, and in most cases it wins me over.

Cheers! -the Pig

[PigFish]

35 minutes ago, CaptainQuintero said:

Re the kits, I think the 75% calibration kits are around because the older style hygrometers from calibre etc would only recalibrate to 75%and no other value. There wasn't the ability to adjust the calibration until the newer models of 'cigar hygrometers' were released a few years ago

 

Do Boveda packs come with certs? So that is the catch.

What might be being said here is that they are satisfied with the accuracy of the 75rH bag, yet not so sure of the others! Each salt is different. And each bag presumably has different salts or the aqueous salt solution bag (Boveda pack) does not perform as intended. They may not recommend the 65% bag for calibration because they are not really comfortable with the claims that they have made about the labeling, and then the certification of the claims!

Food for thought! -Piggy

[BarryNY]

21 minutes ago, PigFish said:

And Barry, what is perfect? You see that is the hitch. Perfection and satisfaction are not the same. Perfection may be a goal for a 'hung-up' guy like me and maybe it is right for you. 

Cheers! -the Pig

I'll leave it as we're both "well hung"....I mean both "hung up"..........

I'm just concerned that what soon will be $3,000-$4,000 worth of cigars today will be very satisfying after resting in the appropriate climate conditions for the next 2-5 years!

[stogieluver]

Great thread, everybody.   Thanks to Barry for starting and playing along.  And PLEASE forgive me, goo and NSX, for leaving you out of the page for help. 

[BarryNY]

Yes all good...thought and sh-t stirring is fun - and I am happy to say that FuGu is 100% accurate in his description of how these electronic hydrometers report - as I did some additional sleuthing for my own education.

[Cigars4me]

Pig, does you head ever hurt from having so much knowledge? You da man! 

[Fugu]

On 29/09/2016 at 1:34 AM, stogieluver said:

Great thread, everybody.   Thanks to Barry for starting and playing along.  And PLEASE forgive me, goo and NSX, for leaving you out of the page for help. 

haha, just seen this now (thread slipped out of view), all good, mate! There's good reason why people FIRST think of Piggy!

 

[Fugu]

On 28/09/2016 at 6:30 PM, PigFish said:

Gooey and I recently had an interesting interaction about accuracy of equipment. I think it might have surprised him some, that a guy (like me) who sells this stuff, would tend to 'boohoo' instrument accuracy. Now mates, I am not against it, but I understand it. Accuracy can be expensive and while it is a useful tool, in some ways it is only a language that we share. He made a point about accuracy (long term) and sensor creep. Of course that was astute and correct, yet creep is an argument about then the period of sensor calibration.

So, if in a broad sense, rH calibration is a means to communicate rH, a language, what is the language worth to you? That is the question I always ask.

This is why I tend to rely mostly on the smoking experience as a judgement of my instrumentation. Yes, my settings mean something to me, but in the vast internet world, when I post 60/70... does it come with a NIST cert? Do I post a cert with each post? No it does not and no I do not.

Piggy, I like your post, and believe me, I totally get your mindset with regard to "accuracy", still, as previously discussed, I have a slightly different one:

Cigar storage is much about providing a continuum as we know. Ideally, instrumentation should help us to monitor conditions and provide a kind of fix point in and over time. It is not so much about minimizing the absolute error in your monitoring sytem - we don't need a NIST or UKAS or whatever certification for our purposes - but it rather is about realistically assessing and knowing about actual measurement uncertainties, that is, the error margin of a particular reading in temperature and humidity. Holding in particular, when having to replace or switching instrumentation. Without regular calibration you won't know about that. And without knowing that, you could likewise do without any monitoring instrumentation from the get-go. Without - regular - calibration it virtually is a blind flight. You can rely on manufacturer's specs here or you can keep control yourself. Getting cheapo equipment calibrated at an accreditation lab is a non-option really....you know that Piggy...

However, your very argument of the final fixpoint being taste / smoking experience is a valid one of course, I concur. But with taste as your "sensory system" you are relying on a system with a certain time lag that allows you to only react at hindsight, in particular if something went wrong (I am aware it won't happen with your equipment, but... well, who knows better than you...). So, for simple practical reasons, I fear we all are still relying on "technical sensorics", with all their flaws and shortcomings, for real-time monitoring of storage conditions. But you were spot-on indeed with your critical assessment in the mentioned thread reg. a proper calibration procedure. If not done correctly, one is at risk relying on systematically false figures in the end. That might indeed eventually be worse than simply keeping to the device "as is". As in all things in life, you should know what you're doing (and be aware of what you are being capable of doing!...).

Cheers,
Goo