36 which is boltably connected to the valve stem assembly 29 in a manner such that application of regulated pneumatic pressure applied to the pneumatic pressure inlet port 37 acts on the pneumatic diaphragm 35 to apply force against the diaphragm guide 60 which in turn reacts against the plunger 5 and the valve stem assembly 29 the pressure regulating action will be explained in greater detail infra additionally the hydraulic pressure regulator valve 8 has a well bore pressure inlet flange 38 which is boltably connected to the valve bonnet 36 an integral part of the well bore pressure flange 38 is the well bore pressure sensor piston assembly 39 the well bore pressure sensor piston assembly 39 is movable slideably axially and is sealed to the internal walls of the well bore pressure inlet flange 38 via an elastomeric seal 61 i e an o ring pressure applied through the well bore pressure inlet flange 38 will act against the well bore pressure sensor piston assembly 39 is such a manner as to slide the piston 39 axially contacting the pneumatic diaphragm 35 the force exerted by the well bore pressure against the well bore pressure sensor piston assembly 39 acts in conjunction with the force exerted by the regulated pneumatic pressure at the inlet port 37 against the pneumatic diaphragm 35 fig3 is a cross sectional view of a system consisting of the hydraulic regulator valve 8 the adaptor spool 6 and the blowout preventer 5 all boltably mounted to an acceptable blowout preventer assembly those knowledgeable in drilling practice will accept that the.