Pressure tanks used with undersink reverse osmosis units are miniature versions of pressure tanks used on residential water wells. When the RO tank is empty of water, it should have a pressure of five to 10 psi air. As water is forced into the tank by operation of the RO unit, pressure inside the tank increases, in a RO Water Purifier full/heavy tank, air pressure should be 30-40 psi. To be accurate, air pressure should be 2/3 of incoming water pressure. When the tank is full, and if feed water pressure to the RO system is 60 psi, then a full tank should have 40 psi. The RO Water Purifier Pressure tank has a bladder inside, and this bladder separates air from water.
Air Pressure and Reverse Osmosis Tanks
There is a small air charge between the outside of the bladder and the inside of the tank. It's the air pressure that pushes the water out of the tank when you open the faucet. When you purchase an RO unit or a new tank, the tank is usually pre-charged with air.
Reverse Osmosis Water Storage Pressure Tank - White 1/4" Male Threads
Model Pro-190119 Maximum Operating pressure 50 PSI Factory Pre Charge 7 PSI Pressure Vs Capicity (GAL/L) 20 PSI-1.7/6.43 30 PSI-2.2/8.33 40 PSI-2.5/9.46 50 PSI-2.8/10.60 Drain the first tank of water to clean the tank, please re-charge your tank to 7 psi when pressure drops. When applied in drinking water application, sanitize the tank once a year.