Propane Piping

Need some help with propane pipe sizing on a new construction. In Arizona at about 7,000 ft elevation. Will be using 2 - 100# propage tanks connected to a Camco Automatic Changeover 2-Stage Propane Regulator for Dual Propane Tanks. Will be using black pipe throughout but not sure on the sizing. Here is a image of what we are planning: Attachment 42901 (http://www.doityourself.com/forum/attachments/plumbing-piping/42901-propane-piping-propane.jpg)