Baker Water Systems Potable Water Thermal Expansion Tank (MPIX/MPI Series). Required when back flow preventers seal off the system prevents the relief valve from discharging on every heating cycle. Powder coated liner in the water-containing area provides positive protection against rust and corrosion and meets sanitation requirements. Must be installed on the cold water supply side of the water heater, between the water heater and check valve or back flow prevention device.

• Drawn Steel Construction
• Butyl Diaphragm
• Two-Part Powder Coated Liner
• Maximum Working Pressure 150 PSI
• 50 PSI Air Charge (field adjustable)
• 2-Year Limited Warranty
• 3/4" MNPT connection

Start-Up Cycle With water chamber empty, diaphragm is pressed against bottom of chamber.

Fill Cycle As water is pumped into water chamber, diaphragm is forced upward into air chamber.

Hold Cycle When pressure in air chamber reaches pump cut-off point, diaphragm is in uppermost position, water chamber is filled to rated capacity.

Delivery Cycle When water is delivered to system, pump remains shut off. Air pressure in top chamber forces diaphragm downward.

Pressure Tanks Guide