Pressure relief valves shall be vented upwards to a safe area so as not to impinge on buildings, other equipment, or areas that could be occupied by the public (e.g., sidewalks). The discharge vent line shall be able to withstand the pressure from the relief vapor discharge when the relief valve is in the full open position and shall permit sufficient pressure relief relieving capacity. A spring loaded or counterbalanced rain cap shall be provided on the discharge vent line. The rain cap shall permit the pressure relief valve to operate at sufficient relieving capacity.