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Superiorfiltration technology
String-wound Filter Cartridges
01/2005 Revision 1
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Sedifilt string-wound filter cartridges:New developments in filter media
• No media migration– Yarn consists of continuous filaments.– No short fibers to come loose and migrate.
Sedifilt media
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Sedifilt string-wound filter cartridges:New developments in filter media
• No media migration• No chemical leaching
– No chemicals to leach out with new melt spinning and yarn forming process (patented).
– No downstream foaming in filtrate.– 100% pure polypropylene.
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Illus
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Sedifilt string-wound filter cartridges:New developments in filter media
• No media migration• No chemical leaching• True graded density
– New winding technology.– Continuously controlled pitch, number of
crossings and space between each strandof yarn.
– Denser winding in inner layers,coarser winding in outer layers.
– Consistent winding tension.high structural integrity,more consistent performance.
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Sedifilt string-wound filter cartridges:New developments in filter media
• No media migration• No chemical leaching• True graded density• High dirt holding capacity
– Longer life as particles are trappedthroughout the cross-section of the filter.
Illus
trat
ion:
Sed
ifilt
grad
ed d
ensi
ty s
truc
ture
Fin
er inn
er layerM
ediu
m m
idd
le layerC
oarse o
uter layer
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Sedifilt string-wound filter cartridges:New developments in filter media
• No media migration• No chemical leaching• True graded density• High dirt holding capacity• High bulk media
Better performance– Media with high bulk, stable, three-
dimensional random structure with multi-lobal cross section filaments.
– Captures more particles compared to conventional filters.
– Improved solid to void ratio gives higher flow rates with low pressure drop.
Multi-lobal cross section
High bulk media
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Sedifilt string-wound filter cartridges:New developments in filter media
• No media migration• No chemical leaching• True graded density• High dirt holding capacity• High bulk media
Better performance• 100% polypropylene
– 100% pure homopolymer polypropylene.– Wide chemical compatibility.– Excellent micro-organism resistance.– Environmentally safe.– Ease of disposal.– Incinerates to trace ash.
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Sedifilt string-wound filter cartridges:New developments in filter media
• No media migration• No chemical leaching• True graded density• High dirt holding capacity• High bulk media
Better performance• 100% polypropylene• High structural stability
No particle unloading– Firm, stable structure.– No shifting of media.– Improved resistance to particle unloading.– More consistent performance.– Excellent knife-edge sealing.
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Sedifilt string-wound filter cartridges:New developments in filter media
• No media migration• No chemical leaching• True graded density• High dirt holding capacity• High bulk media
Better performance• 100% polypropylene• High structural stability
No particle unloading• Environmentally friendly
– Environmentally friendly disposal.– Incinerates to trace ash.– No hazardous volatiles.
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5 micron, 10” polypropylene cartridge:Test results
Test Method: Water atambient temperature (25 °C.)Flow in US gallons per minute
Test Method: Efficiency and Capacityper ASTM F795-88Instrumentation: LD 400 SN 95020054Fluid: WaterFlow Rate: 3 gpm (US)Temperature: AmbientContaminant: ISO Fine Test DustShut Off delta P: 21 PSI
Test Method: Retention Efficiency andCapacity per ASTM F795Instrumentation: LD 400 SN 95020054Fluid: WaterFlow Rate: 3 gpm (US)Temperature: AmbientContaminant: ISO Fine Test Dust
Test Method: Retention Efficiency andCapacity per ASTM F795Instrumentation: LD 400 SN 95020054Fluid: WaterFlow Rate: 3 gpm (US)Temperature: AmbientContaminant: ISO Fine Test DustShut Off delta P: 21 PSI
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Sedifilt string-wound filter cartridges:Economic benefits of Sedifilt
• Increased filtration capacity– Higher dirt holding capacity
• Longer lifetime– Fewer change outs
• Reduced costs– Less labour requirement
– Less equipment downtime
– Lower inventory levels
5 micron 10" Dirt holding capacity
Ordinary string-wound 30-55 gm
Sedifilt string-wound 108 gm
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Sedifilt string-wound filter cartridges:Filter cartridge range: End adapters and extended cores
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Sedifilt string-wound filter cartridges:Filter cartridge range
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Sedifilt string-wound filter cartridges:Applications
• RO Pretreatment (SDI Reduction)• Drinking Water and Beverage Processing• Sea Water Desalination• Deep Well Injection • Gas Purification• Cooling Tower Water Filtration• Electronics and Electroplating• Industrial Process Water• Pharmaceutical & Healthcare• Chemical Industry• ED Automotive Paint• Photographic Solutions• Wastewater Disposal• And more …
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Comparison with conventional media
String-wound Filter Cartridges
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Conventional media cross-section
• Round cross-section• Fewer micro-voids• Lower dirt holding capacity• Higher resistance to flow
Conventional mediacross-section
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Sedifilt mediacross-section
Sedifilt media cross-section
• Multi-lobal cross-section• More micro-voids• Higher dirt holding capacity• Lower resistance to flow
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Comparison with conventional media:Conventional media vs. Sedifilt media
• Sedifilt media has a higher void to solid ratio, giving higher flow rates, improved dirt holding capacity, and lower pressure drop.
Sedifilt mediacross-section
Conventional mediacross-section
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Conventional string-wound filter cartridges:Problems with conventional media
• Media migration– Short fibers are not properly or fully locked into the main body.– Fibers tend to come loose and migrate into filtrate with flow of liquid
and pressure surges.– Loose fiber ends protruding from the surface can be seen clearly in
friction-spun yarn media.
Friction-spun yarn media
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Conventional string-wound filter cartridges:Problems with conventional media
• Media migration• Chemical leaching
– Spin-finish chemicals (lubricants, surfactants, antioxidants, antistatic agents, emulsifiers, bactericides, etc.) leach out.
– Evident as foaming in filtrate.– Washed media is never 100% ‘clean’.
Friction-spun yarn media
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Conventional string-wound filter cartridges:Problems with conventional media
• Media migration• Chemical leaching• Particle unloading
– Round cross-section media have unstable structure.– Under conditions of flow and pressure surges, unstable round yarns
shift, giving rise to ‘tunneling’ effect and particle unloading.
Unstable structure of conventional cartridge of friction-spun yarn allows a paper clip to be pushed through the media.
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Conventional string-wound filter cartridges:Problems with conventional media
• Media migration• Chemical leaching• Particle unloading• Poor knife-edge
sealing– Unstable edges cause
seal by-pass problems.
Conventional cartridge of friction-spun media
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Conventional melt-blown cartridges:Melt-blown media
Only Advantage: • Freedom from process
chemicals
Disadvantages:• Tendency to collapse
under moderate pressure differential
• Requires supporting core
• Very poor knife- edge sealing
• Particle unloading
Melt-blown filter cartridge
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Resin-bonded filter cartridges:Resin-bonded media
Disadvantages:• Higher cost• Limited chemical
compatibility• Bonding agent
compatibility problems• Poor density grading• Lower dirt holding
capacity• Prone to media
migration – media crumbles easily
• Poor knife-edge sealing
Resin-bonded filter cartridge
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Pleated paper cartridges:Pleated paper media
Only Advantage: • Absolute ratings are
possible
Disadvantages:• Consists of more than
one material• Weak strength of thin
paper media• Pleat pinch-off and
pleat collapse problems
Pleated paper cartridge
Pinched pleat
Collapsed pleat
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Comparison of surface and depth filtration
• Direct interception• Particles larger in size than the
pores deposit on surface of media
• Numerous tortuous flow passages
• Direct interception and dirt retention within depth of media
• Complex mixture of mechanisms
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Reduced costsIncreased
filtration capacityHigher performance
Superiorfiltration technology
Longer lifetimeString-wound Filter Cartridges