Filter-Pak® Gravity Filters

The Graver Filter-Pak™ filter is a gravity type filter that combines the advantages of the Monoscour and Scour-Pak™ filters. It is a heavy duty, self cleaning installation using vigorous air scour followed by water backflush. The Filter-Pak filter successfully incorporates the economic advantages of roughing filtration followed by polishing, with air scour.

All flow control and operating components necessary for automatic operation are provided. Filter compartments can be either square or rectangular.  The number and size of cells is determined by the application. Experience shows that when conventional filter media is preceded by roughing filters, much longer operating cycles and higher rate capabilities exist. The Graver FilterPak offers two-stage filtration:

Advantages Of The Graver Filter-Pak Filter

  • Heavy-duty (High influent turbidity) filtration.  Handles high turbidity loads and sticky particles.
  • The media stays clean even with sticky particles because of vigorous air scour preceding the backflush using the unique underdrain design.
  • It can be operated at substantially higher than normal flow rates on moderately turbid waters.
  • Air scour also substantially reduces the volume of water required to clean the filter.
  • The key design features have been proven by more than thirty years of use.
  • Substantial cost savings are possible because the filters provide their own backflush water in most cases, thus eliminating all of  the equipment needed for conventional gravity filter pumped backflush.
  • Filter layout, cell size and number of cells are infinitely variable to suit any plant space and flow requirements.
  • Filter-Pak produces consistently high quality effluent by positive head, gravity flow without the need for pumps, siphons, or vacuum pumps.
  • Valves and controls are accessible for easy maintenance.
  • Inlet flow distribution is achieved hydraulically, without complex
    instrumentation and flow controls.

Typical Applications

  • Clarifier Effluent Polishing
  • Cooling Tower Sidestream Filtration
  • Reverse Osmosis Pretreatment
  • Iron & Manganese Removal
  • Direct Filtration With or Without In-Line Coagulation

How it Works

Filtering: Water enters at the inlet flow trough where the inlet flow is hydraulically split among all compartments. It flows down through the filter bed into the false bottom of the filter and then into a common weir compartment, preceeding a clearwell.  Flow continues until a pre-determined pressure drop builds up across the bed in one compartment. This compartment then automatically ends the service cycle and begins the cleaning cycle. The length of the service cycle depends on the quantity and nature of the turbidity in the water being filtered.

Draindown and Air Scour: During drain down, the water level in the cell is dropped to prevent loss of media during air scour. This is done by closing influent valve A and outlet valve W, and opening the draindown valve U and the backflush outlet valve C. When the correct level is reached, the air scour timer starts and the blower delivers air to the plenum chamber under the strainer plate through an air distributor and then through air metering tubes into the filter bed. The patented Partilok strainers produce a vigorous scrubbing action which loosens all dirt from the filter media. No water is used during this operation. After a suitable period of air scour, normally five minutes but adjustable, the air scour step ends.

Backflushing: The filter is normally backflushed with water provided by the other cells remaining in service. The necessary head is achieved by the
effluent head weir, while the flow rate is set by means of an adjustable
stop on cell isolation valve W. The bed is expanded by the upflowing
water, which carries the dirt already loosened by the air scour to
waste. The quantity of backflush water needed to clean the bed effectively
is substantially reduced because of the prior air scour. The quantity of backflush water used is adjustable. This step completes the cleaning
cycle and the filter is automatically returned to service by closing the
backflush outlet valve and opening the influent valve.

Photo Gallery

Filter-Pak® Gravity Filters

The Graver Filter-Pak™ filter is a gravity type filter that combines the advantages of the Monoscour and Scour-Pak™ filters. It is a heavy duty, self cleaning installation using vigorous air scour followed by water backflush. The Filter-Pak filter successfully incorporates the economic advantages of roughing filtration followed by polishing, with air scour.

All flow control and operating components necessary for automatic operation are provided. Filter compartments can be either square or rectangular.  The number and size of cells is determined by the application. Experience shows that when conventional filter media is preceded by roughing filters, much longer operating cycles and higher rate capabilities exist. The Graver FilterPak offers two-stage filtration:

Advantages Of The Graver Filter-Pak Filter

  • Heavy-duty (High influent turbidity) filtration.  Handles high turbidity loads and sticky particles.
  • The media stays clean even with sticky particles because of vigorous air scour preceding the backflush using the unique underdrain design.
  • It can be operated at substantially higher than normal flow rates on moderately turbid waters.
  • Air scour also substantially reduces the volume of water required to clean the filter.
  • The key design features have been proven by more than thirty years of use.
  • Substantial cost savings are possible because the filters provide their own backflush water in most cases, thus eliminating all of  the equipment needed for conventional gravity filter pumped backflush.
  • Filter layout, cell size and number of cells are infinitely variable to suit any plant space and flow requirements.
  • Filter-Pak produces consistently high quality effluent by positive head, gravity flow without the need for pumps, siphons, or vacuum pumps.
  • Valves and controls are accessible for easy maintenance.
  • Inlet flow distribution is achieved hydraulically, without complex
    instrumentation and flow controls.

Typical Applications

  • Clarifier Effluent Polishing
  • Cooling Tower Sidestream Filtration
  • Reverse Osmosis Pretreatment
  • Iron & Manganese Removal
  • Direct Filtration With or Without In-Line Coagulation

How it Works

Filtering: Water enters at the inlet flow trough where the inlet flow is hydraulically split among all compartments. It flows down through the filter bed into the false bottom of the filter and then into a common weir compartment, preceeding a clearwell.  Flow continues until a pre-determined pressure drop builds up across the bed in one compartment. This compartment then automatically ends the service cycle and begins the cleaning cycle. The length of the service cycle depends on the quantity and nature of the turbidity in the water being filtered.

Draindown and Air Scour: During drain down, the water level in the cell is dropped to prevent loss of media during air scour. This is done by closing influent valve A and outlet valve W, and opening the draindown valve U and the backflush outlet valve C. When the correct level is reached, the air scour timer starts and the blower delivers air to the plenum chamber under the strainer plate through an air distributor and then through air metering tubes into the filter bed. The patented Partilok strainers produce a vigorous scrubbing action which loosens all dirt from the filter media. No water is used during this operation. After a suitable period of air scour, normally five minutes but adjustable, the air scour step ends.

Backflushing: The filter is normally backflushed with water provided by the other cells remaining in service. The necessary head is achieved by the
effluent head weir, while the flow rate is set by means of an adjustable
stop on cell isolation valve W. The bed is expanded by the upflowing
water, which carries the dirt already loosened by the air scour to
waste. The quantity of backflush water needed to clean the bed effectively
is substantially reduced because of the prior air scour. The quantity of backflush water used is adjustable. This step completes the cleaning
cycle and the filter is automatically returned to service by closing the
backflush outlet valve and opening the influent valve.

Photo Gallery