Clean the valve thoroughly with recommended cleansing (sterilising) tablets. Move the valve head back and forth (Open to Close) while rinsing under mid warm water until it moves freely without any major resistance. Wait until fully dried and move the valve head back and forth (Open to Close) ensuring that it moves freely before attaching to the POWERbreathe K-Series device. For more detail please refer to your POWERbreathe K-Series manual section 11 Care and Maintenance.