Using a 4" hose instead of a 2" hose can increase the flow rate when pumping water from a fire hydrant, but the extent of this increase depends on the restriction imposed by the 2" meter compared to the 500 feet of 4" pipe. The elevation rise of 500 feet equates to approximately 217 psi, which could significantly impact flow rates. It's essential to consider whether the hydrant's pressure is boosted and to have pressure drop or Cv data for the flow meter to make an informed decision. Ultimately, the choice of hose size should be based on these pressure considerations and flow restrictions. Proper authorization is required to operate a fire hydrant.