DW 183 for DN 65 . DN 200 flange connection. Flow switches are used for visual andor electrical checkingof liquid flow. The units are of rugged, glandless construction, and areavailable in several versions to suit a wide variety of industrial flowmonitoring applications. DW 183 (standard) for horizontal or vertical pipelines.with flanged connections DN 65 to DN 200, 3 to 8, 150 lb.indicator G or A.1 or 2 electrical limit switches.measuring system P.