65% Beads - 62F & 80%RH - Beads are Dry

[RLembke]

Winter is always a strange time for humidors, that's nothing new. Lately though, I've been encountering some readings that just don't make a lot of sense. Can any shed any light on this?

I have a college-sized refrigerador with 1/2 lb of 65% beads. I have maybe 6 boxes worth in there. The fridge is down in the basement do it's pretty cool this time of year.

I've had readings that I didn't quite trust with my Honeywell temp/hygro so I recently purchased one of the digi units from Cigarmony with the calibration kit. Calibrated the new hygro and verified the accuracy of the old one (it was spot on).

I've been looking at readings in the neighborhood of 60-62 degrees and 80%RH for several weeks now. At the same time, my beads are bone dry!

Is the 65% regulation by the beads only valid at/near 70%? Are the beads simply trying to maintain a finite quantity of water in the air? Seems to me RH is just that.....relative regardless of temp.

Any thought?

[Da Klugs]

Is the fridge running?

[Rploaded]

Adding to Dave's question, whats the RH of the Basement......Do you by chance have a very moist basement or does you heating system include an aprilaire system, if so those can kick alot of moisture into the basement.

Let us know........

-R

[RLembke]

Thanks for the replies.

Nope, the fridge isn't running. Just utilizing the sealed-up space that would otherwise just be empty space in the basement.

RH of 1st floor is 38% (the Honeywell hygro is doing ambient duty now). Don't know what the basement is but since it isn't on the HVAC system and I do have a humidifier running on the central heat I would assume it is 38% or lower. It's very dry in the house as a whole and the humidifier runs every time the heat is on.

Not sure the ambient conditions would make a great deal of difference seeing as the frigador is it's own sealed environment and the beads are dry. The beads aren't working at all to remove humidity....they keep drying out.

At first I was concerned that I had a bad seal and I was losing humidity like crazy somewhere. That's what led me to suspect the hygro was horribly wrong. Two hygros and several really tight smokes lead me to believe they are telling the truth.

[stevieray]

Something is way off here. 80 rh is Bad Bad Bad. When you say "college size refrig" do you mean the square 1.2 Cu. Ft size? If it's larger, you might need more beads. I know alot of people double up the amount of beads in the winter to maintain humidity. First thing I would do is buy a cooler, put the beads and cigars in the cooler and try to get the humidity down in the sticks. Now....was the fridge recently used (couple of months ago) then unplugged? Check for standing water in the ice tray holder. Could be left over from defrosting if recently used. If you are sure that the Hygrometer is correct...and there is no water in the fridge....I would say that for the 20 Bucks it'll cost for a cooler with a tight seal you will be alot better off ..instead of trying to mess around with the fridge.

[RLembke]

I know the exact volume is on the unit and I checked it prior to ordering the beads but from looking at the units on CC's website, it's somewhere around 2-2.5 cu ft. Viper says 1/2lb should be enough for this size.

That said, the beads that are in the unit are dry....not trying to remove humidity....not happy with the current environment. I can understand maybe needing more beads if I was unable to keep the RH up or if they were always soaked and couldn't remove moisture fast enough but they are doing neither. They are giving up water like crazy despite 80%RH.

Been the cooler route. Been setup in the frig for around 9 months. During the summer months, the frig does a much better job of maintaining RH than the cooler....seals tight as a drum. I know coolers work well but I don't see how moving from one sealed enclosure to another would fix this problem. If I had a bad seal somewhere, I should be having buku problems keeping RH up given the ambient conditions.

The frig was unused for the better part of 3 years prior to it's being promoted to active stogie storage duty. Prior to being habitated, it was left open for several days, cleaned thoroughly and left to breathe another few days to get rid of any cleaner reside.

Oh, and I've only used distilled water on the beads. No funny stuff there.

[stevieray]

hmmm...have you checked to see what the humidity is in the basement? Also, have you changed the batteries in the Hygro? Sometimes when the batteries get weak the Rh reading get thrown off.
The 80 % is the wierd part...If the RH is 80 the beads should be wet. I have used 65% beads for over a year with temps in the range of 60-70 and they hold rock solid at 65%. Maybe shoot Viper an email and ask him.

[madurolover]

Originally Posted by stevieray

Maybe shoot Viper an email and ask him.

[fizguy]

Here is my contribution. Keep in mind that I don't own any beads...though I hope to soon.

Are you sure they are bone dry? Have you used a hair dryer or something to make sure?

[RLembke]

As I said above, being winter and damn cold here for the past several months, it's been very dry. My other hygro is on the first floor monitoring living conditions and this morning it said 38% and 68*. Since the basement is cooler than the rest of the house and not on the active-humidified HVAC system, I would imagine it's lower than 35%RH and somewhere around the 62* that the frigador is at.

The digihygro from Cigarmony is brand new a few weeks ago and has been calibrated with the Humidipak calibration kit.

During the summer when the temps in the basement are higher (around 70-75 depending on the month), I've had the same experience as you, stevie. RH was right around 65-67%.

I have a hunch that the temp is what's causing this problem. I'm going to try moving the frigador tonight to a climate controlled area of the house and let it breathe to lower the humidity and 'start over' in the new environment.

I'm looking for more technical information on this media but I am having problems. My hunch is telling me that the beads are trying to maintain the partial vapor pressure of water vapor, not necessarily the RH. Come to think of it, I don't know how that would be possible without some form of active control by the media - it would have to know the temperature and then adjust the partial pressure it is trying to maintain. This would mean temperature has a major factor. For every change of ~+20F the saturation vapor pressure of water vapor increase by a factor of 2.

[RLembke]

Originally Posted by fizguy

Here is my contribution. Keep in mind that I don't own any beads...though I hope to soon.

Are you sure they are bone dry? Have you used a hair dryer or something to make sure?

I wondered the same thing. When I was calibrating the new hygro, I pulled the beads out of the humi and left them at ambient for about 18 hours. Appearance was the same. I guess the bigger day-to-day gauge I have for the dryness of the beads is relative....I can spray them and have about 50% clear....several days later they are back to being opaque.

So short answer....I don't know for sure that they are 100% dry but I do know they are giving off water vapor and certainly not absorbing any.

Thanks for the thought

[grinch]

Yeah......I truly don't understand it either. The beads should be soaking up excess humidity, or at least, not drying up at all, with 80% humidity. Something makes no sense.

[RLembke]

I have some numbers now that seem to agree with what's going on as of late. From what I can understand of the make up of these beads (similar beads, actually), here are my thoughts. I'd love to hear what other technically minded folks think about this hypothesis. I'm no physics major but my mech eng mind seems to think this is accurate.

The silica beads are somewhere around 90% silica gel. Silica gel works wonders as a humidity control media due to it's amazingly large surface area. This large surface area allows it to have a low vapor pressure (relative to other surfaces). The amount of surface area determines it's actual vapor pressure for water vapor. Depending on the density of the pores and channels, different beads will have a different vapor pressure (hence different "RH" beads).

At any given temperature, air has a saturation vapor pressure for water vapor. A few of those pressures @ temp are:

60F - 17.7 mb
70F - 25.0 mb
80F - 35.0 mb

As you can see, as the temp increases, so does the saturation vapor pressure.

The equation to determine the relative humidity of a given environment is:

RH = P(H2O) / P*(H2O)

where

P(H2O) is the partial pressure of water vapor and
P*(H2O) is the saturation vapor pressure @ the temp of the gas mixture

**Everything up until here is pretty factual minus a few mis-used words possibly. From here on is where I think this makes sense but I could very well be wrong.**

I have 65% RH beads in my frigador and during the summer I remember the temperature being 70F with RH readings of 65%. If we assume the beads and the humidor environment were at equilibrium (50% clear beads and 50% opaque beads = equilibrium), we can determine the vapor pressure of the beads. From the scientific charts for saturation vapor pressure of air @ 70F, the value of P* is 25mb.

RH = P / P*
.65 = P / 25mb
P = 16.25mb

For a fixed media, I don't see how it would change it's specific vapor pressure. As far as I can tell, it's the physical structure that determines at what point it reaches equilibrium with the environment.

So, back to that equation....if we *think* we know the vapor pressure of the beads, we should be able to tell what RH the beads will reach equilibrium with an air mixture at a specific temperature.

Let's take 60F. P of the beads is 16.25mb and P* for air @60F is 17.7 mb.

RH = P / P*
RH = 16.25 / 17.7
RH = .918

If the beads truly have a fixed vapor pressure regardless of temperature (not sure of this), if the beads were to reach a 50% clear/50% opaque equilibrium with the humidor, your hygro would read 92% RH!

This seems to explain why I can't keep any water on my beads even while the hygro says it's 80%RH in the humidor...the beads will want to give off water until the hygro reads 92%!

Thoughts? Any physics majors in the house?

[trogdor]

What humidity readings do you get in your fridge-a-dor do if you remove the beads?

If the beads are dry, and your house is dry, where the heck is the humidity coming from?

Do the cigars feel wet and spongy?

[RLembke]

Originally Posted by trogdor

What humidity readings do you get in your fridge-a-dor do if you remove the beads?

If the beads are dry, and your house is dry, where the heck is the humidity coming from?

Do the cigars feel wet and spongy?

The cigars have been tight on the draw lately but not necessarily spongy or wet.

The humidity will fall if the beads are left dry or removed.

Read the above explanation. The moisture is coming from the beads whenever I refill them. My assumption to this point has been of the "the beads are always going to be right so just keep them happy" mentality but now I feel that has been a serious error. I'm going to experiment by bringing the closed system as it is currently is up to 70F and see what happens to the readings. Physics says says the same 62F/80%RH air will become 70F/57%RH air.

If that is true and the beads resume normal operation to maintain a 65%RH @ 70F, I would say the statement that these beads maintain RH requires a disclaimer......"at or near 70F".