In certain specific areas such as outdoor applications and corrosive atmospheres, such as coastal installations, there is a need for high surface protection to prevent failure due to corrosion. Today's food safety standards often call for daily treatment with detergents to protect against bacteria growth, again producing a need for high surface protection. SCA-X SS are check valves with a built-in stop valve function. CHV-X SS are check valves only. The valves are designed to open at very low differential pressures, allow favourable flow conditions and are easy to disassemble for inspection and service. The valve cone has a built-in flexibility to ensure a precise and tight closing towards the valve seat. A well balanced dampening effect between the piston and the cylinder gives an optimal protection during low loads and against pulsations.