PWP Accumulator Tank With Wall Mount Bracket 1/2" Female NPT 2 Gallon 2 gallon 1/2" Female NPT Custom wall Brackets included Reverse Osmosis Expansion Tank Max Liquid Pressure: 130 PSI Pre-Pressurized Air: 30 PSI Applications: Used on gas, oil, or electric, direct-fired, residential water heater and water storage tank applications to absorb the increased volume of water created by thermal expansion.