A nominal Cooling Tower ton is defined as the capacity to cool 3 gpm of water from 95℉ entering water temperature to an 85℉ leaving water temperature at 78℉ entering wet-bulb temperature. For the 10℉ temperature difference, the 3 gpm water flow is required, however Cooling Towers can be designed for higher temperature differences in order to down size the Cooling Tower and pump condenser water piping system. See table below.
Delta T (℉)
It should be noted that using higher temperature differences (other than 10℉) for condenser water will reduce the chiller efficiency.