If you tell us where you are at there may be a lampworker in your area that can help you. Plumbers are not usually a good idea, unless they see another set up and understand what you need.
Maybe taking a plumber to this site can help him understand. It can help you too.
http://www.artglassanswers.com/forum...84ce5866b4d9e6
Lots of pictures and drawings and the actual math formula for figuring out your air needs etc.