The invention relates to a backpressure-adjusting
pilot operated
safety valve. The backpressure-adjusting
pilot operated
safety valve comprises a main valve and a
pilot valve; the main valve comprises a main valve body, a main
valve seat, a main valve flap and a main valve bonnet; the
pilot valve comprises a
pilot valve body, a
pilot valve seat, a pilot valve flap, a pilot valve bonnet and a pressure adjusting device, wherein a pilot valve body
inlet channel is communicated with a main valve body inlet cavity through a
pipe fitting. The backpressure-regulating pilot operated
safety valve is mainly characterized in that a flow limit hole communicating a main valve backpressure cavity with the pilot valve body
inlet channel is formed in the side wall of the pilot
valve seat, a pilot valve outlet cavity is communicated with a
discharge cavity of the main valve body through a
discharge channel, the
discharge channel, the pilot valve body
inlet channel and a
pipe fitting outlet channel form a three-way channel, a three-way valve is arranged in the three-way channel, one end of a three-way valve flap is provided with a seal surface mutually matched with the end opening of the
pipe fitting outlet channel, the other end of the three-way valve flap is provided with a seal surface mutually matched with the end opening of the discharge channel, and the outer circumferential surface of the three-way valve flap is in clearance fit with the inner
cavity wall of the pilot valve body. The backpressure-adjusting pilot operated safety valve can prevent a medium contained in the discharge cavity from flowing backwards and has the advantages of being good in
backflow preventing property, reliable in reverse sealing property and the like.