<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Why is it that most baseball fields/commercial designs with long runs, they reduce the pipe size as the run goes on? <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
To save money!
Like SamIV says, they size the pipe based on the amount of water that must flow through it (relative the how much pressure loss they can tolerate).
However, it thing the main point RVLI was trying to make is accurate...
The tiny 1/2" pipe just can't adiquately feed three sprinklers, especially since the dry run involved 1/2" or 5/8" garden hoses (lots of pressure loss when trying to push enough water to feed three sprinklers).