isnt it supposed to be a minimum of 6″ of RED brass??
Oops! You’re correct. I was passing through a “senior moment” of confusion when I typed “yellow” brass. I was also thinking about some valves that I’ve used that are, in fact, golden yellow, and quite well suited to connections to galvanized iron pipe and fittings.
To make amends, I’ll add a few comments about the different types of brass. Brass is an alloy of copper and zinc. Red brass is indeed reddish in color and has about 80% Cu and 20% Zn. Yellow brass has about 60-70% Cu and 40-30% Zn, and is light yellow. It is the zinc which really creates problems with electrolysis, especially in connections to galvanized pipe that are coated with…you guessed it…zinc.
There is, however, a yellow brass that is an alloy of about 90% Cu and 10% Zn. This is called “antique yellow brass.” It is even better than “red” brass for dielectric connections. Fittings, especially valves, are made of this low-zinc “yellow brass.”
Bronze, for those who are interested, is an alloy of copper, zinc, and tin, which, so far as I know, is not used in modern plumbing.