1
098-0003 Rev. B
1.0 THEORY OF OPERATION
This system is designed to pretreat and purify water for use in health care applications. Below
is the sequence of the water progression as it goes thru the components of the MOBILE SPD
SYSTEM. Each component’s theory of operation is listed in order of water progression thru
the system.
RO:
The process of osmosis can be reversed by placing pressure upon the feed water side
(concentrated solution side) of the membrane. Water will be forced through the membrane
barrier to yield water that is purer on the lower pressure side of the membrane than on the
more concentrated solution side (higher pressure side) of the membrane. The feed water will
become more “concentrated,” and will be discharged through the reject port known as “reject
water” or “concentrate”. Liberation of purer water from its solutions is caused by the reversal
of the osmotic pressure; (the operation termed as “Reverse Osmosis”). Reverse Osmosis is
commonly referred to as “RO”.
DI:
Mixed Bed De-ionizer contains both the cation and anion resins in a single vessel. The
purpose of mixing the resins is to achieve a very high quality deionized water. As water
passes through the mixed bed, it has millions of chances to contact a cation resin bead, then
an anion, then another cation, another anion, and so on. An exchange takes place, of course,
only when a positive ion contacts a negative exchange site, and vice versa. With each
exchange, purity of the water improves because more ions are removed and held by resin
beads. Mixed bed deionizer is utilized as a polishing unit downstream of the RO.
STORAGE TANK:
The reverse osmosis unit makes a limited amount of water at a time. It is therefore necessary
to store it in a storage tank. The storage tank is equipped with float switches, which will turn
the reverse osmosis unit off and on when the water reaches a predetermined point in the
storage tank.
This tank is also equipped with a spray nozzle on the return loop side of the tank. This allows
disinfectant to reach all parts of the tank when it is applied to the tank, for faster disinfections.
The vent filter on the tank is designed to filter the air when water moves in and out of the
storage tank. Tanks are equipped with a “rupture disk”, which will break if the flow of air/water
becomes too much for the filter or tank to handle.
The storage tank is equipped with 2 float switches, which will turn the
reverse osmosis unit off when the water reaches the predetermined cutoff point and
turn the RO on when the tank is drained to the appropriate level float. The
distribution pump on the storage tank will cycle whenever there is a pressure drop
detected.
