The valves don't need to be replaced regularly, like filters do. The main thing with them is periodically cleaning them, and this is easily done by rinsing them with warm water and allowing them to dry. If conditions are particularly humid, you can apply a very small amount of talc to keep the rubber flap from sticking. Aside from rinsing, you only really need to replace them if they become damage or broken, or if you notice them not sealing properly when you inhale. Hope that helps!
Answer by: (Admin) on Jan 19, 2015 6:49:34 PM