Abstract: A valve and seal arrangement for extended life in a positive displacement pump. The arrangement may take on different configurations. The seal may be secured within a shielding sidewall of a valve head for isolation from differential pressure during striking of the valve head at a valve seat. Additionally, the seal itself may include an axial tail for sealing off the fluid chamber below and defined by the seat prior to the striking of the valve head at the seat. Further, a horizontal flange defining a clearance of no more than about a layer of an abrasive constituent of a slurry being pumped may be utilized. That is, as opposed to, or in addition to, sealing in advance of striking, flow may be reduced to no more than a constituent layer thickness in advance of the striking. Other similarly advantageous architectural valve features may also be employed.