501B 系列顶部导向型单座调节阀，采用流体压力平衡型阀芯结构，因此与 501T 顶部导向型单座调节阀相比，能够承受较高的工作压差，同时由于采用平衡密封环使控制阀动态稳定性更好；与 501G 套筒导向型单座调节阀相比，更能适应流体中含有一些颗粒杂质的场合，而且不易造成阀芯的卡死。

501B series is top guided single seated control valves, Compared with 501T series top guided single seated globe valves, Its dynamic stability is better with balance seal and could work smooth under higher pressure drop. Compared with 501G series cage guided single seated control valves,  it's better suited for applications involving fluid with entrained particles, and its trim will not be locked.