31 Forced ventilation is required to prevent the sealer from re-flowing and puddling, as well as for thorough drying. I removed the old drain plug from the outlet, and inserted an air line fitting (the thread wasn't the same but I didn't plan on using the sender again, so I wound the fitting in!) in order to hook up my air line. Eastwood recommends a pressure of between 1-5 psi. I'd also bent the old pickup tube so the air didn't blow directly at the side of the tank.