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Beyond the water
purification components themselves, care must be exercised with
the design and operation of the storage tank and the Purified Water
distribution piping. Generally, bacteria multiply less rapidly at
this point in the system because nutrients to support growth are
present at much lower levels than within the treatment components.
Nevertheless, improperly designed or managed systems can be sources
of substantial amount of bacterial contamination.
a) Storage
- Storage
vessels to have cylindrical shape and conical outlet where D to
H ratio
should be between 1/2 to 1/3.
- Material
of construction should be SS-316 or SS-316 L if extensive Welding
is involved.
- The internal
surface must be mirror polished having 250 grit finish Vergin
rolled plates chemically cleaned preferred.
- Water inlet
to have spray ball system and placed such that entire inner surface
is washed.
- Breather
for Air Vent is installed with 0.1hydrofobil filter element.
- Manhole
for physical cleaning.
- Electronically
operated level indicators/Digital level indicator / controller.
- Vessel can
be jacketed for steam heating if required.
b)
Distribution
- Two critical
parameters in design of distribution system is sizing and minimisation
"dead legs" having continuous loop.
- Material
of Construction should be SS-316 L descaled and electropolished
suitable for sterilisation stem at 30 psig.
- Tri-clover
with silicone rubber gaskets joints.
- All bends
and piping system should be demuntable type for ease of cleaning
and re-installation.
- Pipe to
have adequate slope to allow draining of pipe completely.
- Dead legs
should not be more than 6 times the diameter of pipe.
- Velocity
of flow through the pipe should be minimum i.e.
- Pipe joints
:- Orbital welding type or expanded type.
- Valves :-
Diaghram type (Saunders make).
- User point
loop should be continuous having skid design.
- Pipe to
be mounted independently avoiding any supports from wall preferably
mounted as pendants.
- Entire pipe
work should always be purged with water.
- Sample points
to be provided at appropriate points for validation.
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