Abstract: A frangible pressure relief disc assembly is disclosed which is adapted to fit into a positive displacement pump on the suction side of each cylinder. The disc assembly provides a pressure relief when the fluid passing through the pump encounters a closed valve or other obstruction in the line. The disc assembly comprises: (a) a support member having a first side and a second side which is penetrated by a passage (e.g., a bore ) providing fluid communication from the first side to the second side, and (b) a pressure frangible disc fixedly attached to the support member and positioned to form a fluid-tight seal covering the passage.