Low pressure relief valve

A pressure relief valve comprising:

• a valve body having an inlet port and an enlarged cylindrical bore extending axially into said body in alignment with said inlet port to define an enlarged valve chamber;
• an outlet port opening laterally from said valve chamber at a location spaced from said inlet port;
• a seat insert member threadedly received in said enlarged bore and sealed with said body to define an axially facing raised seat closely adjacent the wall of the bore and circumferentially about said inlet port at a location upstream of said outlet port at an elevation substantially corresponding to the elevation of said outlet port;
• a poppet valve mounted in said chamber, said poppet valve having a truncated conical configuration with a maximum outer diameter only slightly less than the inner diameter of said enlarged bore and a first end face for engaging said seat and blocking flow from said inlet to said outlet;
• said maximum outer diameter of said poppet valve being adjacent said first end face and sized to provide guiding movement on the inner diameter of said enlarged bore;
• a bonnet threadedly received in said enlarged bore at a location axially spaced from seat insert;
• a stem carried in said bonnet to extend into said enlarged valve chamber in axial alignment with said seat insert;
• said stem having a cylindrical end portion received in a cylindrical opening formed axially into said poppet member on the end thereof opposite said seat insert, said cylindrical end portion and said cylindrical opening being sized to permit lateral shifting and alignment of said poppet valve member relative to said seat while preventing excessive unwanted tilting of said poppet valve member relative to said bore such that said poppet is guided by the inner diameter of said enlarged bore and the outer diameter of said cylindrical end portion of said stem;
• and
• means for maintaining said stem member and said poppet valve member under a predetermined bias toward said seat.