短語詞組短語pressure e reducing valve 減壓閥primary pressure of reducing valve 一次壓proportional pressure -reducing valve 比例減壓閥secondary pressure of reducing valve 二次壓one way pressure -reducing valve 單向減壓閥Needle valve Pressure -reducing valve 針閥constant difference pressure -reducing valve 定差減壓閥constant pressure pressure -reducing valve 定壓減壓閥 返回 pressure reducing valve