The PA piston accumulator provides optimal lubrication to promote long seal life and reliability for double mechanical seals using Plan 53C piping systems in oil and gas and chemical applications. It provides a constant supply of clean, cool and pressurized barrier fluid to the faces of the dual mechanical seal. The pressure source for the barrier fluid system is the pump seal chamber. This allows the piston accumulator to track the seal chamber pressure and boost the pressure to the mechanical seal. The PA piston accumulator is optimized to have a working volume that meets API 682, 4th edition and is larger than the standard working volume for a 5-gallon API reservoir.