At ‘fourwents’ we feel every application deserves its own optimal solution. That's why we have developed the widest line of rotary joints. There's a ‘fourwents’ product to meet almost any Need, whatever the process, speed, medium or other application condition. Fdu series - water & general purpose unions is one such range which includes sizes from 1/4" to 3 " suitable for water, hot water, intermittent steam & hot oil applications.