LIAG^® non-return valves (check valves) reliably prevent products from flowing back into pipes. Non-return valves of the 61A, 62A and 63A series are provided with a 4-way controlled metallic disk seal which reliably prevent the so-called flutter effect up to an operating pressure of 20 bars (290 psi). The disk seal of the 62B series is in metal, that of the 62C series in Teflon. LIAG^® non-return valves have CIP capability, feature a compact design and can be taken apart in a single step.