Calcium chloride in DIY dehumidifier - safety ?

[SentinelAeon]

I like doing simple home gadgets for fun and to learn something new. I am trying to do a simple DIY room dehumidifier consisting of calcium chloride, a fan blowing over it and water collecting cup. But i also found some health concerns regarding calcium chloride - namely using it at home and blowing into it, the dust is supposed to not be to good for lungs. Since i do not know much about chemistry i have 2 questions that i hope you can help me with:

1) I am thinking whether it would be possible to cover the fan exhaust with some kind of filter to prevent this dust to enter the room air. But i need to know how small this dust is to know the MERV value of filter i need to choose

2) Is there maybe some cheap safer alternative i could use ? Rock salt ? 

[exchemist]

19 minutes ago, SentinelAeon said:

I like doing simple home gadgets for fun and to learn something new. I am trying to do a simple DIY room dehumidifier consisting of calcium chloride, a fan blowing over it and water collecting cup. But i also found some health concerns regarding calcium chloride - namely using it at home and blowing into it, the dust is supposed to not be to good for lungs. Since i do not know much about chemistry i have 2 questions that i hope you can help me with:

1) I am thinking whether it would be possible to cover the fan exhaust with some kind of filter to prevent this dust to enter the room air. But i need to know how small this dust is to know the MERV value of filter i need to choose

2) Is there maybe some cheap safer alternative i could use ? Rock salt ? 

I don't think CaCl2 is too bad a health hazard, compared to alternatives. I can't help you with particle size of the CaCl2 as this will depend on where you get it from. As soon as it starts to absorb water from the air I think the particles will clump, suppressing any dust.  

But I wonder how effective your dehumidifier will be. The moisture of saturated air at 20C is 17g/m³, so in a room that is, say, a 3m cube you have about 450g (1 lb) water present. if the relative humidity is 100%. That will need quite a lot of CaCl2 to remove. You won't be able to collect any water, as what it does is absorb the water. As it is deliquescent, you will eventually have a concentrated liquid solution of CaCl2. 

[SentinelAeon]

It seems to be quite cheap so it shouldn't be to much of a problem to replace it. I wanted to include a collector bin under it to collect water and i can just dispose of the water/solution when it is full. Bin can be like 10L or 20L. 

[exchemist]

32 minutes ago, SentinelAeon said:

It seems to be quite cheap so it shouldn't be to much of a problem to replace it. I wanted to include a collector bin under it to collect water and i can just dispose of the water/solution when it is full. Bin can be like 10L or 20L. 

OK, give it a try then and let us know how it goes. 

[SentinelAeon]

I hope someone can shed some light on that dust in the meanwhile, i guess it cant be smaller than HEPA, but getting air through HEPA with small PC fans is very hard. 

Btw, you seemed almost surprised at the use of calcium chloride, i just wanna double check that i didnt mess up the name terribly somehow ? But in shops i often see those little boxes, inside the box at the top is compartment for tablets and i assumed that was calcium chloride, and then as the air passes through this tablet, as it liquifies, it will drain to the bottom of the box. I even saw some variants with a fan but that is where i found some clear warnings that fan and calcium chloride is not a good combination because of the dust. And that is what got me into wanting to know the size of it to see if filtering it could be a solution. 

[chenbeier]

Calciumchloride will absorb water until it changes to liquid. So probably not good idea to use it and blow air over it.