86 replies to this topic

[Mark]

Mark: I use a device known as, Moisture Eliminator. It has a plastic screen/lid over a moisture-permeable white sheet that covers pellets made of calcium chloride dihydrate (CaCl2 72H2O). Under the pellets is a plastic divider, and water trapped by this device is stored under the plastic divider and pellets. It's supposed to absorb twice it's weight in water. This device can be used to keep any room or area dry...laundry rooms, basements, bathrooms, closets, utility rooms, electronic storage areas, etc..
Even out here in the desert of El Paso, with very low humidity, it's managed to trap a goodly amount of water in it's reservoir from my closet. I thought it may help eliminate odors caused by using that closet as a dirty cloths hamper. It has!

I doubt you could safely drink the water absorbed by the calcium chloride dihydrate (Orpheus should know about that), but the device says to empty the water contents into the sink when it's used up, and not to allow it to come in contact with skin. It's an irritant, but is non-toxic.
However, this simple device clearly demonstrates how simple it is to trap the relative atmospheric humidity, and store it for periods of time. I need one in my bathroom to trap excess moisture there, as there are no windows to allow ventilation after showers. Even in the desert, that excess moisture can promote mold and mildew.

I think if a device could be made like the one Orpheus has described above, it would have many good uses. Don't survivalists use plastic sheets wrapped around plants to catch the condensation that occurs there with temperature shifts? I haven't read the MIT article yet, but I assume the scientists are looking for a chemical and/or mechanical way to aid in that reaction somehow? I'll read later, and ask more questions. It's an idea that could save lives, so it's worth a little extra time and effort.

Edited by Mark, 24 November 2012 - 01:37 AM.

[Orpheus]

Calcium chloride is a desiccant that sucks moisture from the air like the silica gel or iron filing packets that ship with consumer electronics). More than that, it is deliquescent, meaning it will actually suck water out of the air until it literally dissolves in that water. The reaction is pretty exothermic -- you can feel it heat up when it's absorbing water rapidly.

I use it all the time, but rather than let it go all the way to a liquid state, I bake the moisture out in an oven and re-use it (not energy efficient, perhaps, but more practical in my lab). Direct sun in a closed container might bake out some of the moisture, but being deliquescent, it's an uphill battle with low yield. And alas, you can't drink CaCl solution. Not beneficially, anyway.

Aqueous CaCl is a good refrigerant working fluid, because it doesn't like to freeze, and is used on roads, to dissolve ice in the winter and to absorb moisture to keep dust down in the summer.

The CaCl granules I use contain another calcium salt, cobalt chloride or some other indicator, so they are white when dry (anhydrous) and slowly turn blue as they absorb moisture (others go from light blue or pink when dry to Purple when damp), giving an indication of when to shake the container up or bake it.

-- Orpheus "it's a pretty bad shake'n'bake for meat poultry or fish, alas"

[Orpheus]

I've long admired Ben Krasnow, who once swore to do a hack a day for a year -- and kept going when the year was done. The sheer ambition (and persistence) of making a "Homebuilt X-ray backscatter imaging system (airport body scanner)", though, is impressive, even for him.

[Orpheus]

For your amusement, I present "Just try and make your own coil gun"

[Orpheus]

Quote

voici ma creation. une copie du x-finger adaptée àma morphologie.
il n'est pas fini, j'ai encore des modifs fonctionnelles a lui apporté et aussi des moulages silicone.
si quelqu'un s'y connait en silicone je suis preneur

[Orpheus]

It would be wrong to pretend that all creative solutions work out well.

You have gasoline. You have a source of fire. You are surprised by an unwanted snake. Connect the dots.

[Santaman]

Ooooh tech thread!

My favorite garden tool!


Bagger 288 the largest moving machine on land, thirteen and a half thousand tons of metal.


"Little" Brother, Bagger 260 on the way to a different digging site, its too expensive to take these machines apart, its easier and cheaper to move them around in one piece.


Bagger 260 again, its waiting for a replacement part for one of the tracks, pretty impressive idle sound it has...