A furnace rated at 120,000BTUH is to be installed 50 feet from the gas meter, it will be supplied by natural gas at an 11 water column, .6 specific gravity, .5 pressure drop and a rated value of 1000BTU per cubic foot. What is the size of the gas line?

A furnace rated at 120,000BTUH is to be installed 50 feet from the gas meter, it will be supplied by natural gas at an 11 water column, .6 specific gravity, .5 pressure drop and a rated value of 1000BTU per cubic foot. What is the size of the gas line?