When should a swing check valve be used instead of a ball check valve?

Answer:

The primary advantage of a swing check valve is the much higher flow coefficient (Cv) in larger size valves. A higher Cv value results in reduced pressure drop across the valve. For example, the pressure loss (?P) across a 4" true union ball check valve at a flow rate of 300 GPM is [Q/Cv]2 = [300/345]2 = 0.76 psi. For a 4" swing check valve, (DP) = [Q/Cv]2 = [300/514]2 = 0.34 psi.