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View Full Version : How do those Goldenrod thingies work in a gun safe?



PhaseLockedLoop
09-27-2010, 12:31 PM
A while back canoeyawl posed a rhetorical question about dehumidification that ran, roughly, "...where does the water go? It can't just disappear..." He answered the question with respect to the situation under discussion, but I thought about the Goldenrod dehumidifiers for gun safes. Their ads say "GoldenRodŽ is the safest method of controlling and eliminating dampness" So where does the water go? I understand the notion of heating air in the safe so it rises to the top, keeping the guns warm enough so condensation doesn't occur on them. But in a sealed safe, this isn't eliminating dampness? Not having AC handy to my safe, I keep my guns in gun rugs with a fair-sized dessicant module in each. If it's really humid out, I seal them in ziplock bags, so the condensation is on the bags, not the guns.

Anyway, whatever damp air is in a safe when you close it seems like it won't be eliminated by a heater. But I understand that they work, so what am I missing?

Ed Harrow
09-27-2010, 12:46 PM
I dunno, but it sounds a lot like a 'brisker' - a gizmo that looks like a plugged in bread box. It's great for crackers, chips, etc when the humidity is high. By raising the temperature within, it lowers the relative humidity within, plus raises, slightly, the temps of the guns, thus reducing the inclination of those water molecules (there's still pretty much the same number of them) to condense, in this case, upon the steel.

htom
09-27-2010, 12:54 PM
From their FAQ:

GoldenRodŽ heats to a surface temperature of less than 150 degrees (which is almost too warm to hold) and circulates warm, dry air throughout an enclosure on a 24 hour basis. This increases the temperature of the air inside to several degrees above the ambient outside temperature. Expansion of the heated air forces the moist air outside through the vents or loose fitting doors leaving the dry air inside. In order to work correctly, it is important to ensure that there is adequate ventilation.

So it seems that it's pushed out of the safe.

Ed Harrow
09-27-2010, 01:54 PM
I'd like to hear the physics behind that.

B_B
09-27-2010, 02:54 PM
I'd like to hear the physics behind that.
Warm air is less dense than cold air and carries more moisture. As the air is warmed it expands and absorbs water from within the cabinet, as it expands the higher pressure forces some of this air out of the 'confined' space, carrying the moisture with it.

Or something like that... ;)

Ed Harrow
09-27-2010, 05:14 PM
And what comes in to take its place - I'm just sayin' (Dalton's Law and all that)

B_B
09-27-2010, 05:21 PM
Cold air which is subsequently heated, thus expands, drawing more moisture and being expelled - how much this happens depends on the air circulation, air-tightness of the cabinet, and location of holes.

or something like that... ;)

paladin
09-27-2010, 05:32 PM
Ed...they shot the Daltons a long time ago.....

sorry...just woke up for some more dope.....

Bruce Hooke
09-27-2010, 06:56 PM
If I have done the math right, at around room temperature, air expands by about 0.35% per degree Celsius change in air temperature. This means that if the air temperature in the gun safe is raised by "several degrees" (let's read that as 3 deg. C or 5.4 deg. F) the air in the safe will expand by approximately 1%, meaning about 1% of the air will be expelled and thus, presumably, about 1% of the moisture. That strikes me as pretty darn irrelevant (remember that this is not an ongoing process where 1% of the air is expelled per some unit of time but rather a one-time effect where that only takes place when the air temperature is changing, not when it has reached a steady state). Ed's explanation makes much more sense. Heat air up and the relative humidity drops and thus condensation is less likely.

I thought about the scenario of house in winter to see if that had any application. A leaky house is drier in the winter than a tight house because the leaky house is constantly letting in more low-humidity air from outside (low-humidity because it is cold and does not hold much water) and heating it up, thus making it even drier, while the moist air inside is lost to the outside. However, if I am thinking about this right, this only "works" if there is a source of moisture within the heated space. There are lots of sources of moisture inside a typical house. There should not be sources of moisture in a gun safe as far as I know.

So, it seems to me that the better reason for GoldenRod to say that the safe should have some ventilation is to make sure that if cold, dry air enters the house (through normal air exchange with the outdoor air) and the temperature in the house and thus the gun safe drops by more then the heater can make up for, you are not in a situation where damp air is trapped in the gun safe and condensation forms as this air is cooled.

I hope the GoldenRod FAQ answer is an example of some marketing person writing about something they don't understand and failing to run the answer by the engineering people, rather than the engineers failing to grasp basic physics!

Phillip Allen
09-27-2010, 06:59 PM
I'd like to hear the physics behind that.

it's easy Ed...those safes are not sealed...just locked

Phillip Allen
09-27-2010, 07:01 PM
btw, I don't think it is a good idea to slow cook my firearms...think of wood and scopes

Bruce Hooke
09-27-2010, 07:10 PM
it's easy Ed...those safes are not sealed...just locked

That does not resolve the question of physics that Ed raises. See my post for more details...

Phillip Allen
09-27-2010, 07:16 PM
If I have done the math right, at around room temperature, air expands by about 0.35% per degree Celsius change in air temperature. This means that if the air temperature in the gun safe is raised by "several degrees" (let's read that as 3 deg. C or 5.4 deg. F) the air in the safe will expand by approximately 1%, meaning about 1% of the air will be expelled and thus, presumably, about 1% of the moisture. That strikes me as pretty darn irrelevant (remember that this is not an ongoing process where 1% of the air is expelled per some unit of time but rather a one-time effect where that only takes place when the air temperature is changing, not when it has reached a steady state). Ed's explanation makes much more sense. Heat air up and the relative humidity drops and thus condensation is less likely.

I thought about the scenario of house in winter to see if that had any application. A leaky house is drier in the winter than a tight house because the leaky house is constantly letting in more low-humidity air from outside (low-humidity because it is cold and does not hold much water) and heating it up, thus making it even drier, while the moist air inside is lost to the outside. However, if I am thinking about this right, this only "works" if there is a source of moisture within the heated space. There are lots of sources of moisture inside a typical house. There should not be sources of moisture in a gun safe as far as I know.

So, it seems to me that the better reason for GoldenRod to say that the safe should have some ventilation is to make sure that if cold, dry air enters the house (through normal air exchange with the outdoor air) and the temperature in the house and thus the gun safe drops by more then the heater can make up for, you are not in a situation where damp air is trapped in the gun safe and condensation forms as this air is cooled.

I hope the GoldenRod FAQ answer is an example of some marketing person writing about something they don't understand and failing to run the answer by the engineering people, rather than the engineers failing to grasp basic physics!

I got a better one Bruce. Let us suppose that yoour conditions exist and the safe is actually sealed similar to a mason jar...the warm air then pushes past the seal and when the lights go out during a storm and the safe cools, the thing seals and you cannot open the door at all

Bruce Hooke
09-27-2010, 07:24 PM
I got a better one Bruce. Let us suppose that yoour conditions exist and the safe is actually sealed similar to a mason jar...the warm air then pushes past the seal and when the lights go out during a storm and the safe cools, the thing seals and you cannot open the door at all

I in no way meant to suggest that the safe is or should be sealed like a Mason jar. My explanations all assume a safe that will allow some air exchange with the room air. I would agree that your scenario of a sealed safe being impossible to open under certain circumstances could be very real. The same situation happens with watertight cases (e.g., Pelican cases) and for this reason the good cases include a system to equalize the pressure between the inside and the outside. I am not sure if turning off the GoldenRod alone would be enough to create a substantial vacuum in the case, but add changing barometric pressure to the mix and you could certainly create an interesting situation.

Ed Harrow
09-27-2010, 09:33 PM
Water molecules are rather unique - they are a bi-polar molecule

http://upload.wikimedia.org/wikipedia/commons/thumb/c/c7/Water_molecule_2.svg/500px-Water_molecule_2.svg.png

(I liked the ones I used to draw better, I made them look like Mickey Mouse.)

The little guys are the Hydrogen atoms and, in the case of this molecule, they cause a very slight '+' charge, and the Oxygen atom a '-' charge. This means that water molecules stick to stuff. Water is the bane of vacuum systems (I don't me home vacuums, I mean research and production systems). One will NEVER get the water out of such a contraption, but enough energy can be put into the system to raise the temp and, since hot air can hold more water than cold air, effectively lower the relative humidity.

I bet the reason for the vents is simply to help control the temperature within the cabinet, and the effect could just as well be gained with a couple of light bulbs (tho they might enduce other, undesirable, issues).

http://upload.wikimedia.org/wikipedia/en/thumb/4/41/Relative_Humidity.png/400px-Relative_Humidity.png

Looking at this chart - at 15C 10Gr of water / KG air = 100 % relative humidity, but at 25C it equals only 50%.

Phillip Allen
09-27-2010, 10:49 PM
if Smith & Wesson start making light bulbs and selling them in a camo box, gun stores will do a brisk business...expecially if the word "tactical" appears on the light bulb box somewhere

this in response to Ed's notion that light bulbs would do as well as the goldenrod thingy...

B_B
09-27-2010, 11:03 PM
I bet the reason for the vents is simply to help control the temperature within the cabinet, and the effect could just as well be gained with a couple of light bulbs.
yes I suspect so also

BrianW
09-28-2010, 12:00 AM
yes I suspect so also

I also agree. Just like a light bulb in the bilge.

Canoeyawl
09-28-2010, 10:54 AM
I use a volatile corrosion inhibitor in my tool boxes and in the gun cabinet and under the covers on a few motorcycles in storage.
A study conducted a few years back (by me!) came to the conclusion that very few -none- of the so called moisture protective sprays actually include corrosion inhibitors in the cocktail. (I just called tech support for the various products and asked the question - Does your product have a corrosion inhibitor?)

The paper that bearings come wrapped in is treated with volatile corrosion inhibitors, it has a distinctive odor and condenses on the same surface that water may condense on.
I just wrap a sheet of this treated paper around the piece in question.

PhaseLockedLoop
09-29-2010, 08:03 PM
So it seems that it's pushed out of the safe.

Got it. I shulda read the FAQ. Thanks.

Ed Harrow
09-29-2010, 09:09 PM
Got it. I shulda read the FAQ. Thanks.

If ya believe that, I have a bridge in Brooklyn I wanna sell ya.