Larger tangential fans have 6- to 40-inch-diameter wheels that can be 3 to 10 feet long. They pull the air in over the whole length of the wheel, turn it 90 degrees and blow the air out over the whole length of the wheel. The result is a uniform airflow pattern over the whole length of the wheel. These fans can operate outside the furnace or oven to provide quick and uniform cooling, or they can be placed inside the furnace or oven to spread the heat out uniformly. The fans can be installed in temperatures up to 1300°F. They are available for air volumes from 20 cfm to 50,000 cfm.