Any chemists? Cobalt Blue silica question.

[HammsBeer]

I have a question for any chemists here about moisture indicating silica. I have about 70 of these sealed 40g desiccant tins (quarter for size reference), and use them for long term ammo storage in surplus ammo cans (one tin per can). The packaging says to recharge them in the oven at 300 F for 3 hours, I usually heat them at just 200 F for 3 hours, and I recharge them once a year in winter (low relative humidity).

They use the blue to pink saturation indicator Cobalt Chloride, and I've read some concerns it might be a carcinogen. My question is, if I'm not crushing the silica beads, licking them, eating them, storing food with them, or any other stupid uses, do they pose a vapor risk being dried in low heat in the oven as intended?

 

[M-Cameron]

Cobalt Chloride has a boiling point of 1,920 degrees......the boiling point would be when it converts to a gas.

so heating it at 300 degrees is fine and wont cause it to offgas.

dont lick it and you should be alright.

 

[yugorpk]

Do not eat. Says so right on those little packets in your beef jerky.

Plant Engineer in a chemical plant here. Don't eat them and don't worry about it..

 

[HammsBeer]

Ok, thanks. As long as they are not out gassing fumes then they should be fine.

I recently started a new job in a hospital pharmacy, and part of our work is compounding the liquid chemotherapy drugs for IV administration for cancer patients. I have been reevaluating any cancer risks so I don't end up on the receiving end of these drugs, but my many years of exposure to chemicals and fumes in automotive repair has probably doomed me anyway.

 

[hso]

HB,

They're not giving off anything except water when you heat them.

 

[M-Cameron]

I usually heat them at just 200 F for 3 hours, and I recharge them once a year in winter (low relative humidity).

also remember, water boils at 212 degrees......so if you are only heating them to 200, you may not be getting the full drying effect.

there should be no harm in heating them up to the recommended 300.

 

[230RN]

I'll just plunk these down here:

http://chlorine.americanchemistry.c...ry/Cobalt-Chloride-Colorful-Moisture-Detector

http://www.nilechemicals.com/Cobaltchloride msds.htm

https://en.wikipedia.org/wiki/Isotopes_of_cobalt

Terry, 230RN

 

[dpadams6]

Any more updates on this being a carcinogen?

 

[pkariher]

Suspected carcinogen. But I can only see it a problem if you are eating it. Keep your lips off it.

 

[yugorpk]

The silica gel itself is not poisonous per se'. It could cause silicosis which could lead to lung cancer if you breath it for a long time so don't do that. The indicator that tells you if the gel is dry and active, cobalt chloride ( the stuff they used to put in kids chemistry sets ), is a possible carcinogen. Don't eat it.

 

[hso]

Read the safety data sheets.

It is not listed as a human carcinogen and unless you're ingesting it you'd need a contact exposure pathway (not an issue here) for it to present a problem anyway.

 

[Jim NE]

Not a problem, but I don't mess with those things anymore. In summer, I have a dehumidifier in my gun room and that works fine.