流体从背压阀进口进入，被膜片阻挡，于是流体对膜片产生向上的压力。当压力足够大时，弹簧被压缩，流体顶起膜片形成通道，从背压阀出口流出；若流体压力不够，就会形成憋压，使进口压力上升直到达到额定压力，顶起膜片形成通路。
背压阀的额定压力可调节，一般通过调节弹簧上端的顶杆，从而调节弹簧的长度来实现。
台湾WILSHEN伟圣卸载溢流阀
BUCG系列卸载溢流阀部分型号：
BUCG-03-1-10-1PN-A BUCG-06-1-10-1PN-A
BUCG-03-2-10-1PN-A BUCG-06-2-10-1PN-A
BUCG-03-3-10-1PN-A BUCG-06-3-10-1PN-A
BUCG-03-1-20-1PN-A BUCG-06-1-20-1PN-A
BUCG-03-2-20-1PN-A BUCG-06-2-20-1PN-A
BUCG-03-3-20-1PN-A BUCG-06-3-20-1PN-A
BUCG-03-1-10-1NP-A BUCG-06-1-10-1NP-A
BUCG-03-2-10-1NP-A BUCG-06-2-10-1NP-A
BUCG-03-3-10-1NP-A BUCG-06-3-10-1NP-A
BUCG-03-1-20-1NP-A BUCG-06-1-20-1NP-A
BUCG-03-2-20-1NP-A BUCG-06-2-20-1NP-A
BUCG-03-3-20-1NP-A BUCG-06-3-20-1NP-A
台湾WILSHEN伟圣背压阀
MCA系列背压阀部分型号：
MCA-03-1-10-1PN-30 MCA-06-1-10-1PN-30 MCA-10-1-10-1PN-30
MCA-03-2-10-1PN-30 MCA-06-2-10-1PN-30 MCA-10-2-10-1PN-30
MCA-03-3-10-1PN-30 MCA-06-3-10-1PN-30 MCA-10-3-10-1PN-30
MCA-03-1-11-1PN-30 MCA-06-1-11-1PN-30 MCA-10-1-11-1PN-30
MCA-03-2-11-1PN-30 MCA-06-2-11-1PN-30 MCA-10-2-11-1PN-30
MCA-03-3-11-1PN-30 MCA-06-3-11-1PN-30 MCA-10-3-11-1PN-30