Bell & Gossett 5" flanged Rolairtrol air separator, less strainer. This separator is rated to 425 gpm, 125 psi and 350°F.Removal of air from within the water will increase heat transfer, save energy and increase heating comfort. When the fluid enters the separator it goes across a stainless steel baffle and brush assembly that causes the air sticks to the wire brushes then rise to the top-mounted air vent. The deaerated water then continues though the system.