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Pressure Sand Filters
Traditionally Pressure Sand filters are used for
filtering swimming pool water for trapping suspended & coagulated
impurities. Pressure sand filters use multi grade silica sand as a
filter media. Normal life of these media is 5 to 7 years.
For private swimming pools , the re-circulation water filtration
velocity is around 35 – 40 m/hr. For all other swimming pool, especially
public swimming pool filtration velocity is 30 – 35 m/hr.
Advantage of these type of filter is, they can be
repeatedly used after backwash. When pressure difference increases by 7
psi (0.5 Kg./cm²) than initial service filter pressure, sand filter is
back washed.
Sand Filters are available in different material of
construction as per need. with automatic /semi-automatic & PLC based
fully automatic operations like service, back-wash, rinse etc.
Glass-fiber reinforced Plastic (GFRP) :
GFRP vessels are very long lasting & corrosion resistance.
Pressure Sand Filter in Carbon / Mild Steel
Pressure Sand Filter in Glass Fiber Reinforced Plastic (FRP)
Dia 300 mm to 900 mm are available, which are suitable
for pool volume from 20,000 liters to 1,50,000 liters.
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Public Swimming Pool Pressure Sand Filters : FRP Series |
Public Swimming Pool Pressure Sand Filters : MS
Series |
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Dia 900 mm to 2,000 mm are available, which are
suitable for pool volume from 150,000 liters to 1,000,000
liters.
For higher flow rates multiple no. of filters can be installed |
Dia 500 mm to 3,000 mm are available, which are
suitable for pool volume from 150,000 liters to 1,000,000
liters. For higher flow rates multiple no. of filters can be
installed |
Pressure Sand Filter in Stainless Steel
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» Online self-cleaning filters : clean themselves automatically
when differential pressure (head-loss) across the screen reaches a
preset value
» Uninterrupted water
supply : the filter cleans itself in just seconds without
interrupting mainstream flow
» Modular structure: different diameters from 80 mm to 400 mm,
suitable or use singly or in manifold configuration providing optimal
solutions To meet specific customer requirements
» Flexibility of control options: Hydraulically or electronically
controlled units. Electric control boards To suit specific needs.
Flushing according To pressure differential and/or according To time.
Continuous flushing, alarm signals, flushing counter and more
» Wide range of filtration degrees: from 2 To 3500 micron
» Material of construction : Different MOCs from polypropylene, carbon
steel to stainless steel. Internal parts like o-ring, seal, gaskets are
ozone compatible
» Very minimal waste water : waste water quantity is much less. Less
than 10% compare to that in conventional sand filters.
» Operation & maintenance free : no operator is not required &
maintenance time is few hours only.
» Versatile application : suitable for all types of swimming
pool. Highly cost & waste water effective when water volumes are higher
Internationally used for Olympic size competition pools, municipal
swimming pool, water parks, ponds, lagoon & very large water bodies
Filtering process:
The water enters through the inlet pipe into the coarse screen from
outside in, and through the fine screen from inside out. The "filtration
cake" accumulates on the fine screen surface and causes head loss To
develop. The coarse screen is designed to protect the cleaning mechanism
from large dirt particles. It should not accumulate large quantities of
suspended solids and is not cleaned automatically.
Automatic Self-cleaning process :
• The automatic self cleaning filter will start the self-cleaning
process when the pressure differential across the screen reaches a
pre-set value or a predetermined lapse of time.
• Cleaning of the filter element is carried out by the suction scanner,
which rotates in a spiral movement while removing the filtration cake
from the screen, and expels it out through the exhaust valve. The
rotation of the scanner is operated by a 2-way (fwd/rev) drive unit that
is attached to the scanner by a threaded shaft, providing the linear
movement.
• The exhaust valve is activated For the duration of the cleaning cycle
by a 3-way solenoid. During the self-cleaning process, which takes
approximately 35 seconds, filtered water continues To flow downstream.
Comparisons between automatic & self cleaning filter : (for flow rate
500 m3/hr.)
| Flow Rate : 80 m3/hr (Max.) |
Flow Rate : 1100 m3/hr (Max.) |
| Flushing Time : 10 – 12 Sec./Cycle |
Flushing Time : 10 – 15 Sec./Cycle |
| Waste Water : 20 ltrs./Cycle |
Waste Water : 250 ltrs./Cycle |
| Comparison Aspects |
Automatic Self-cleaning |
Pressure Sand Filter |
| Type Of Cleaning |
On line : Automatic |
Off line : Manual |
| Filtration During Backwash |
Continuous Filtration : Filters During Back
Wash |
Filtration Stops : During backwash filtration
stops |
| Back Wash Cycle Time |
Very Short : 1.0 to 1.2 Minute |
Long : 15 to 20 Minute |
| Waste Water Per Day |
Minimum : 1.0 to 1.5 % of the rated service
flow rate |
Very High : 25 to 32 % of the rated flow rate |
| Filtration Quality |
Consistent: Consistent bet. Two backwash cycle |
Inconsistent : Over the period of time quality
Improves |
| Foot Print (e.g. 500 m³/hr) |
Very Small : 5.0 m ² |
Very Large : 20.0 m ² |
Operation Cost
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Very Low : As no man power required & very lo back wash
water to waste |
Very High : Man power required for operation &
very high quantity of back wash waste water |
Back wash Waste Water
(e.g. 500 m3/hr flow rate) |
Very Low : 7,500
liters/day (approx.) |
Very High : 1,60,000 liters/day
(approx.) |
Payback time considering filter cleaning waste water is
less than 1 year.
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