Series ETX, ETSX Non-Potable Water Expansion Tanks are for use incommercial and residential closed loop hydronic heating system pipingto control the thermal expansion of hot water and maintain systempressure below the relief setting of the relief valve. Thepre-pressurized steel tank features a durable expansion membrane thatprevents contact of the water with the air in the tank. This ruggeddiaphragm minimizes loss of the air change and ensures long andtrouble-free life for the system. Model ETX mounts to supply piping andModel ETSX is free standing. Available in a variety of models andsizes. Maximum Pressure: 75psi (5.3 bar) for ETX and 100psi (6.9 bar)for ETSX.