Designed for one-way air flow. Works great on an airstone, membrane diffuser or any other type of diffuser system to keep water from backing up in your airline, which could freeze in the winter months.
It can also be installed inline to prevent back pressure if you're using more than one aeration system thru the same set of airlines and diffusers.
NOTE: This valve does not prevent back pressure on the windmill or electric aerator compressor should your airline freeze or get constricted. You would need our pressure relieve valve UPART015 or freeze control unit FCU0039 (included in this tab) to do that.
Please note in shopping cart under comments what size to connect 3/8" or 1/2" airline