This 4.5 gallon non-potable water expansion tank is for use in commercial and residential closed loop hydronic heating system piping to control the thermal expansion of hot water and maintain system pressure below the relief setting of the relief valve. The pre-pressurized steel tank features a durable expansion membrane that prevents contact of the water with the air in the tank. This rugged diaphragm minimizes loss of the air change and ensures long and trouble-free life for the system. Maximum pressure is 75 psi (5.3 bar).. Application: Non-Potable Water. Compatible Brand/Model: commercial and residential closed loop hydronic heating system. Finish Family: Gray. Material: Steel Tank. Nominal Tank Capacity (gallons): 5 gal. Pack Size: 1. Product Weight (lb.): 8.5 lb. Returnable: 90-Day. Product Depth (in.): 11.1 in. Product Height (in.): 14 in. Product Width (in.): 11.4 in. Nominal Tank Capacity (gallons): 5 gal