How much air does a forge require? in Articles Posted August 30, 2013 I was always taught that the best way to test for the correct amount of air into a forge was to drop a ping pong ball just above the tuyere and it should just hover above it about 100 mm or 4 inches. Too much air and it flies off and too little and it drops down. This test is done with forge emptied of any fuel. Coke in my case.I have a fan blower which is controlled with a speed controller which I turn back between each heat to conserve fuel and crank up higher when extra heat is required. The ping pong test really only enables you to get the optimum lighting discharge of air. The rest will come with experience and the task at hand.