Disc Filters

Disc filter

Disc filter

Parts of Disc Filter

A Disc Filter is a type of water filter used primarily in irrigation, similar to a screen filter, except that the filter cartridge is made of a number of discs stacked on top of each other like a pile of poker chips. The water passes through the small grooves in between and the impurities are trapped behind. Some types of disc filters can be backflushed in such a way that the discs are able to separate and spin during the cleaning cycle.

Working principle

• As the name implies, the filter consists of a stack of discs. These discs are like hollow poker chips with serrations that cause the discs to interlock when the discs are stacked.
• Water enters the filter chamber on the outside of the discs. The water then flows through the disc pack between the interlocked serrations of the discs. After flowing through the serrations the water then flows through the hollow center of the discs and out to the field.
• Back wash is accomplished by reversing water flow. When flow is reversed, water enters into the hollow area of the disc stack causing the stack of discs to lengthen. As the stack lengthens the discs are separated from one another. Water then freely flows outward pushing all dirt caught between the discs to a dump line. Additionally, water is sprayed through nozzles inside the disc stack aimed outwards causing the discs to spin and rub against each other further cleaning the discs.
• The separation of the discs and the spinning action is the secret of the disc filter. This method of flushing is almost instantaneous requiring only a few seconds to fully clean the dirt off the discs. No other filtration system can equal the speed and thoroughness of the disc filter back wash.

Advantages

• Fast Back Wash - Disc filters can be backwashed in far less time than Sand Filters. A 3 cartridge sand filter requires 10-20 minutes for back washing as the water flow must "fluff" up the sand to push dirt out. A 3 cartridge disc filter can be completely back washed in about 1-1/2 minutes, most of that time being valve opening and closing for each cartridge.
• Low Water Waste - The length of time advantage translates to saving hundreds of gallons of water. If water flow is 50 gpm, the sand filter system in 20 minutes would use 1,000 gallons to back wash. The disc filter would use 75 gallons.
• Space Saving - The disc filter system requires about 1/3 the space of a sand filter system.
• Less Maintenance - Sand must be replaced periodically, and if the sand filter is abused and not backwashed regularly, the sand will require replacement quickly. Disc filters last for many years without requiring replacement because the plastic discs are highly resistant to deposits.
• Less Pressure Required - Disc filters require less pressure to back wash than sand filters. This may allow a smaller supply pump to be used.
• Resistance to Abuse - Failure to back wash a sand filter may lead to complete failure of the sand media requiring that the media be replaced. Failure to back wash a disc filter will lead to low water flow but when the disc packs are backwashed they immediately clean up and are easily restored to service.
• Fast Change - The filtration abilities can be quickly changed simply by changing the disc pack to the size you wish to filter down to. Disc packs are available from 5 microns up to 400 microns.