The use of an accumulator tank is recommended to ensure effective and reliable system function. With an accumulator tank incorporated in the system, the intervals between cut-in and cut-out will be longer when only small amounts of water are drawn off. Less wear and tear on the pump with fewer starts and stops, Pre-pressurized at 12 psi. Volume:.5 gallon/Port connection: 1/2"/Diameter: 6.3"/Height: 12.4"/Weight: 2.7 lbs.