Gradual Pore Plugging 
Ø Happens with soft or hard pargicles
Ø Particles build up on the ¡°pore¡±throat or opening
Ø Most common after prefiltration
Ø Occurs with either biologicals or mon-bilologicals
How do Blocked Filters React?
Ø Gradual blockage most common
¡°Everything was going alright ,then all of a sudden the filter blocked
How do Blocked Filters React?

Maximum delta P
Stated by cartridge manufacturer to saaume integrity of filter
Changeout delta p
Minimize adsorptive overload
Indicates onset of practical blockage.
What Happens when a Filter Blocks?
Flowrate goes down
Ø May drop below the required flowrate (ie filling machine)
Pressure goes up
Ø May exceed the system differential pressure capabilities ¨Ccartridge of tubing/fittings
Ø Particles may ¡°bleed¡±throuth the filter 
Contaminates/blocks the downstream cartridges 

Pressure Sources 
Ø Compressed gas systems 
Ø Centrifugal Pumps
Ø Flowrate decreases as the pressure increases 
Ø Turbines 
Ø Blowers
Ø Positive Displacement 
Ø Tubing(Peristaltis)-lilmited by tubing pressure 
Ø Diapghragm
Rotary Lob

Pressure Measurement 

Ø Differential pressure
Ø Sometimes called pressurd drop,pressure loss,
Ø Indicates the driving force for filtration
Ø Differential pressure is additive 
Ø Pressure Measurement 
Ø Gauge-Used liquid wystems
Absolute Pressure-Used for vacuum or gas systems
Ensure adequate pressure 

If you Increase	Flow Rate	The Affect Differential pressure	Volume Filtered
Flow Rate	¡¡	Increase proportionately	Generally Decrease
Surface Area	Increases proportionately	Stays the same or drops proportionately if the flow rate isfixed	Increase
Pressure	proportionately	¡¡	Generally decrease
Viscosity	Decreases Proportionately	Increases Proportionately	Generally Decrease