Pressure: 20000-200000psi Power: Manual Material: AA, BB, CC, DD, EE, FF ... balance can be achieved, the opening and close of choke valve to control back pressure so that ... finite pressure from casing by adjusting the choke valve’s opening, so balanced drilling can work ... of choke valve, gate valve, pipeline,fittings and pressure gauge etc, see the above drawing and gate valve part and choke valve part. ...