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WHY
DOES A CLOSED SYSTEM NEED A FILTER?
How
to improve system performance and save
money at the same time
Closed
systems
circulate the same body of fluid and
are not subject to blow-down and
makeup in the way that steam boilers
and cooling towers are. The most
common closed system are used for:
*
Hot water heating of apartments, offices, institutions and industry.
*
Chilled water systems used for air conditioning in large buildings
and factories.
The
fluid in closed systems usually
contains a suspension of fine,
abrasive particles which is harmful to
the equipment and leads to unscheduled
shutdowns and increased
maintenance. There are various
sources of these particles, mostly
resulting from corrosion-oxygen
dissolved in the fluid being an
important contributor. Closed systems
are rarely
oxygen-free during operation, due
to constant air leakage through
pressure equalization valves, pipe
joints, pump packing, etc. In
addition, a quantity of oxygen,
although small, is continually added
to the system through makeup water.
Since most systems are largely
constructed of steel, this leads to
the generation and circulation of
suspended iron oxide particles
throughout the equipment. Other
sources of particulate matter are mill-scale
and debris
left over from assembly as well as
material introduced when system is
opened up for routine maintenance.
Closed systems are frequently
constructed of a variety of metals as
a result of galvanic corrosion.
Suspended
iron oxide particles
and other debris, are very abrasive to
mechanical pump seals and can coat or
plug up heating coils, causing them to
lose their heat-transfer
ability. Additionally, areas of
the piping and equipment that become
covered with debris are subject to under-deposit
corrosion, leading to further
damage and release of corrosion
by-products.
Implementing
and maintaining
a properly designed chemical treatment
program is the first step towards
preventing corrosive oxygen from
attacking the metals in the system.
However, since it is virtually
impossible to prevent the introduction
of suspended material the best way to
keep the system clean is by use of a
side-stream filter.
A side-stream filter is one,
which filters a small portion of the
total circulation, usually between 5
and 10 %. These units are relatively
small, inexpensive and use replaceable
elements that may be obtained in
different pore sizes. For most
applications a 30 micro cartridge
gives the best performance. In the
event that the filter becomes plugged
by the sudden introduction of large
amounts of material, the main
circulation stream remains
unrestricted.
The
ideal protection combination is a
comprehensive chemical
treatment program used in
conjunction with a side
stream filter and a flow
indicator. Suspension agents keep
particles suspended until the
side-stream filter removes them from
the fluid. The flow indicator
indicates when it is necessary to
change the filter cartridge and also
provides a visual check on the
appearance of the fluid.
Your
THERMIDAIRE
Representative can advise you on
all your water treatment needs. Call
the experts at THERMIDAIRE
today for more information.
Benefits
of a filter in a closed system:
*
Keeps
the system clean
*
Protects
pump seals
*
Prolongs
the life of mechanical equipment
*
Provides
a warning of sudden system disruptions
*
Reduces
downtime
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Reduces
maintenance and energy costs
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Information
