This is an air relief valve made of nylon for Pentair SM and SMBW 2000 Filters. Replacement part for Pentair SM and SMBW 2000 Filters. This air relief valve can also be used on the old Anthony Apollo DE Filters.
This valve is used on the top of the pool filter tank (and often are referred to as the pressure-relief valve). The valve helps to relieve pressure that builds up inside the filter. By opening up, these types of valves are designed to allow excess pressure to escape. At a normal pressure level the valve should close again.
