december 8, 2020 by G.S.55 FB REG Diaphragm valve G.S.55 Diaphragm valve. These valves are made 1/2” through 3”, and differ from the G.S. 51 model in that they have a valve body with NPT/BSP threaded connections. Related Products G.S.56 DE DIN REG Diaphragm valve G.S.56 DE DIN REG Diaphragm valve G.S.56 FB DE DIN REG Diaphragm valve G.S.56 FB DE REG Diaphragm valve G.S.56 HW Diaphragm valve