What is the best way to clean old equippment.

[fkshiu]

Muriatic acid (AKA hydrochloric acid) IS dangerous by definition:

http://en.wikipedia.org/wiki/Muriatic_acid#Safety

I still clearly recall the big lecture regarding hydrochloric acid safety we got at a chem lab back at university - full face shields and everything - because of its tendency to easily become a corrosive mist.

IME there's nothing in our hobby that an overnight soak in full strength undiluted vinegar can't deal with along with a little elbow grease. Like I said, you can reuse the vinegar over and over again. I've been using the same $4 gallon jug of white Costco vinegar for over a year now. Just don't put in on your fish and chips.

IMO the risks of muriatic acid are not worth the benefits over that of vinegar.