Another option might be to use plastic tanks. They are cheap, and having long experience with plastics in the plating industry, and I can say that polypropylene will certainly tolerate your temperatures of 180F. The tricky part is to support the tank so it will not sag/buckle. Even a 100 gallon...
lzz you didnt' mention if it must be a gas blanket; so also consider the use of a ball blanket (just a bunch of plastic hollow balls) which is very cheap, requires no maintence, and still reduces emmissions by 90%.
You can buy these by the 1000 at USPlastic.com
I have no affiliation with...
If you are very cost sensitive, try posting to www.getafreelancer.com Chances are see one of the coders has something close to what you want, and can write custom software according to your wishes. I guarantee the price will be a fraction of any of the packages mentioned so far.
Simple...
My experience emigrating to the U.S.A. is that you get nowhere from the other side of the ocean. You must visit the U.S., find a job,(New Jersy is the place - not New York City) then apply for legal paperwork.
Simple Process Controls including liquid level alarms. www.drumalarm.com
