The resistance a fan is working against will be dependent upon the equipment the fan is being used in. Each piece of equipment will have a unique system resistance that is a function of the amount of air flow being moved through that equipment. For turbulent flow, the coefficient “n” in the equation will be a 2. The result is the static pressure will increase as a square of the air flow. The system characteristic constant, K, is a coefficient that is dictated by the equipment design. Each unique piece of equipment will have a different value for the system characteristic coefficient. The system resistance curve can be determined through calculation, simulation using CFD software or testing in an air flow chamber.