SURFACE FILTRATION Versus DEPTH FILTRATION In Metalworking Fluids

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SURFACE FILTRATION Versus DEPTH FILTRATION In
Metalworking Fluids

• SURFACE FILTRATION, refers to a method which
  traps particulate on the surface of a disposable
  or permanent filter media. The solids in the
  fluid need to stack up on each other and build a
  filter cake to increase the effectiveness and
  efficiency of the system. In flat bed vacuum or
  pressure filters, the performance depends on the
  nature of the solids, the distribution of the
  particle sizes and the velocity thought the
  media. Generally, 15-20 Micron is the best level
  of filtration on flat bed, surface filters ROLL
  MEDIA OR PERMANENT MEDIA VACUUM AND PRESSURE
  FILTERS

• DEPTH FILTRATION, refers to a method which traps
  particles throughout the cross-section of the
  filter medium. These are also referred to as
  Pre-Coat Filters. In the case of the Star
  Filter, the medium is the cellulose filter aid
  which provides a wide distribution of particles,
  establishes an effective filter cake and provides
  great dirty holding capacity. Because of the
  many types and grades of available filter-aids,
  Pre-Coat Filters can provide filtration to 1
  Micron. PRECOATED PRESSURE FILTERS, STAR FILTER

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BUILDING A FILTER CAKE
A Wide Distribution Of Particle Size And Shape
Creates The Best Filter Cake And Yields High
Filter Efficiency
Filter Cake
Filter Media Or Septum
Coarse Grinding, Aluminum Oxide Wheels
Conventional and Creep Feed Grinding, Where A Mix
Of Material And Wheel Brake Down Is Present
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SURFACE BLINDING
A Narrow Distribution Of Particle Size And Shape
Seals Off The Filter Media Which Results In
Less Dirt Holding And Increase Operation Cost
Surface Blinding
Filter Media Or Septum
Fine Grinding, Honing Diamond CBN Wheels Cast
Iron, Carbide, Glass Ceramics
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FILTER AIDS - PRECOAT
A Filter Aid Can Be Used To Precoat The Filter
Septum Creating A Filter Cake For Trapping The
Fine Particulate
Precoat Filter
Filter Media Or Septum
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THE KEY INGREDIENTS TO BUILDING A CAKE Good
Distribution Of Solids Large Amount Of Filter Area
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FILTER AREA
In Cake Building applications, The amount of dirt
a given area can hold is based on the flow rate
or velocity through the media
10 Square Feet Of Filter Area.
1 Square Foot Of Filter Area.
Low Flow Allows The Cake To Build, Keeping The
Paths Open For Additional Flow To Pass and Dirt
to be captured
High Flow Causes The Cake To Compress,
Restricting The Paths, Leading To Premature
Loading
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FLAT BED SURFACE FILTRATION
Heavy Dirt Load And / Or A Poor Distribution Of
Particle Shape Size
Reduces The Ability To Build A Cake And Leads To
Surface Blinding And Reduced Efficiency
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STAR FILTER DEPTH FILTRATION
MICROSCREEN SEPTUM
Cellulose Filter Aid Creates A True Depth Cake
Contaminates Are Trapped Within The Cake
Which Increases Dirt Holding Capacity And
Filtration Efficiency
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FLAT BED FILTER REGENERATION
Permanent Or Disposable Roll Media
Regeneration Cycle Introduces Small Section Of
New Media
Flow Takes The Path Of Least Resistance, Quickly
Coating The New Section
The New Media Quickly Blinds Off Resulting In
Rapid Regenerations
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STAR FILTER REGENERATION CYCLE
Increase In Vacuum Compress The Filter Cake,
Restricting Flow
A Gentile Backwash Of Clean Fluid Releases The
Compact Filter Cake
The Dense Filter Cake, Laden With Solids Quickly
Settles To The Conveyor
The Entire Filter Area Is Renewed And Recoated So
The Velocity Stays Low Resulting In Long
Efficient Filter Cycles