Pump arrangement including flag type inlet valves with spherical seating

A pump assembly for pumping a material comprising:

• a pump housing partially defining a chamber, an inlet to said chamber and an outlet from said chamber;
• a reciprocating member positioned to increase and to reduce the volume of said chamber;
• an inlet valve positioned in said inlet to allow material flow through said inlet into said chamber as the volume of said chamber is increased and to prevent material flow through said inlet from said chamber as the volume of said chamber is reduced;
• an outlet valve positioned in said outlet to allow material flow through said outlet from said chamber as the volume of said chamber is reduced and to prevent material flow through said outlet into said chamber as the volume of said chamber is increased, each of said inlet valve and said outlet valve comprising;
• a valve seat element having a longitudinal axis, defining a through opening and including a seating surface which defines a portion of said through opening;
• a valve body element positioned in said inlet or said outlet and operatively coupled to said valve seat element and located at least partially in said through opening, said valve body element including an inwardly facing interior sidewall;
• and
• a valve element secured to said valve body element at said inwardly facing interior sidewall and being movable relative to said valve body element, said valve element including a sealing surface which is curved in at least one plane including the longitudinal axis of said valve seat element and is adapted to contact said seating surface to prevent material flow through said through opening.