Pressure operated water valve type WVO is used for regulating the flow of water in refrigeration plant with water-cooled condensers. The pressure operated water valve gives modulating regulation of the condensing pressure and so keeps it constant during operation. When the refrigeration plant is stopped, the cooling water flow is shut off automatically. Pressure operated water valve can be used with flammable refrigerants. Double sealing between the refrigerant and the water line ensures that in case the bellows damage and the refrigerant leak, it cannot enter into the water. This severely limits the safety implications. It means that the valve can be used together with a double walled heat exchanger and water circuit in such a system does not need to be considered as a part of the installation for flammable refrigerants (EN378-1:2008, clause 4.4.2.2).