What is the minimum size schedule 40 pipe between first and second stages in a two stage regulator LP gas system with a total length of 187′, a pressure drop of ½” water column, and a total load of 820,000 btuh?

What is the minimum size schedule 40 pipe between first and second stages in a two stage regulator LP gas system with a total length of 187′, a pressure drop of ½” water column, and a total load of 820,000 btuh?