The check valves illustrated in this chapter are designed for installation on commercial refrigeration systems and on civil and industrial air conditioning plants that use the following refrigerant fluids: • HCFC (R22), only valves in series 3122 • HFC (R134a, R404A, R407C, R410A, or R507) • HFO and HFO/HFC mixtures (R1234ze, R448A, R449A, R450A, or R452A) belonging to Group 2, as defined in Article 13, Chapter 1, Point (b) of Directive 2014/68/EU, with reference to EC Regulation No. 1272/2008. Furthermore, the same check valves, up to DN 25, that is models 3122/9, 3124N/9, 3125N/9 can also be installed on systems using the following refrigeration fluids: • HFC (R32) • HFO (R1234yf) classified as A2L in the ASHRAE 34-2013 standard, and belonging to Group 1, as defined in Article 13, Chapter 1, Point (a) of Directive 2014/68/EU, with reference to EC Regulation No. 1272/2008. For specific applications with refrigerant fluids not listed above, please contact Castel Technical Department.