Wiper ring, 47 mm diameter, for Hanovia PMD, SPA and BMD medium-pressure ultraviolet disinfection systems. The ring is the seal-like element that bears on the quartz sleeve and sweeps it clear. The quartz sleeve is the only optical path between the lamp and the water, so any film of scale or iron on its outer surface cuts the delivered UV dose. The wiper sweeps the sleeve on a timed cycle to keep transmission at the design figure. Hanovia builds this range around two quartz sleeve diameters, 38 mm and 47 mm, and the wiper rings are not interchangeable between them — check the sleeve diameter on your system before ordering. Reference number 2209-1205.