Q?How much flow can I put through a disc filter?

The flow is determined by the quality of the water, and the level of filtration desired.  Following is a chart of maximum recommended flows per disc filter element for various conditions.

Q?What is the minimum pressure required to backwash a low pressure disc system (DLP)?

The minimum pressure required is 21 psi (1.5 bar)

Q?What micron size is each color disc?

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Q?How often will the discs need to be replaced?

The discs are not subject to ware, and are completely cleaned during the backwash cycle therefore replacement should not be required.  If scale or “sticky” particles adhere to the disc, acid can be used to clean the discs.

Q?What is the minimum air pressure required for an AA System (air assist)?

The air pressure required for the AA system is 12 psi higher than the system pressure at the inlet to the filter.

A compressor can be used if no air is available at the installation site.  A 2 HP compressor, capable of storing at least  of 16 gallons (60 liters) of air at a pressure equal to or higher than 130 psi  (9 bar).  To perform an effective cleaning it is necessary to have a  flow of  285 gpm (18 l / sec) at a pressure value equal to or greater than 65 psi (4.5 bar).


Q?What pH levels can the filter tolerate?

With ph levels between pH 4 – 11 none of the filter components will be effected.

Q?What is the minimum pressure required for the decompression of the discs during backwashing – standard equipment?

The minimum pressure to decompress the backwash piston is 15 psi.  This is well below the minimum pressure required for the filter to operate correctly.  The piston decompresses about 17 mm.

Q?What is the maximum chlorine level allowed in the water?

Chlorine levels over 1 ppm are not recommended.  If higher chlorine levels are present, special equipment can be supplied by AZUD.

Q?Is there a minimum flow required for the AZUD disc filter to work?

A minimum flow of 48 gpm (3 l/sec) is required for the automatic AZUD HELIX DISC systems.  This minimum flow is also required for the AA and low pressure systems.

Q?What is the maximum working pressure of the AZUD HELIX systems?

Operating pressure for standard is 150 psi.  For working pressures over 115 psi – 125 psi we recommend using  the HP Series (High Pressure) which can work to pressures of  230 psi

Q?Is the Azud Helix filter compatable with salt water?

Azud manufactures specific equipment for use with salt (SW) / brackish water (AW).  All wetted and exposed metals are manufactured with highly resistant materials giving an extended life in harsh conditions.

Q?Is a back pressure required on the filter system?

Yes back pressure is required.  A pressure sustaining valvew can be used down stream of the filter if there is not enough back pressure.

Q?Which is better, surface or depth filtration?

In surface filtration, particle retention occurs on the outer surface of the filter medium.
In depth filtration, the retention of the particles occurs along the entire path that the water travels through the filter medium.
It is far easier to clean a surface type filter than a depth filter.
The MG disc filters combine both surface and  depth filtration.  A particle not retained on the discs surface travels into the disc channel and is retained captured along the path through the disc.

Q?How often will the automatic filter backwash?

This depends on several factors.  Solids loading, disc size and flow.
The controller will automatically trigger a backwash cycle when the preselected pressure differential is reached.
The key to a properly functioning automatic filter, is to have it backwash as infrequently as possible, using the minimum amount of water and energy.

Q?How clean do the discs get during a backwash cycle?

The support element holding the discs  allows the discs to decompress during the backflush cycle.  The 4 support bars that deliver the backwash water through rectangular slots to the inside of the discs, cause the discs to rotate and vibrate during cleaning.  This results in total cleaning of the discs.

Q?What is the difference between nominal flow and design flow?

Nominal flow is the maximum flow that gaurantees a problem free filtration quality without excessive ware of the equipment.  Design flow is the selected flow after considering water quality, manufacturers specifications and installation characteristics.

Q?How do I size my disc filter?

Sizing of the disc filter is based on the water quality to be filtered and the desired micron level required.

Q?What is the designed operating pressure of the standard AZUD product?

The standard equipment has a maximum operating pressure of 145 psi at 140 degrees F.

Q?What pressure drop should be allowed for across the filter system?

The pressure drop across a clean filter system is low.  The designed pressure drop needs to take into consideration the selected pressure differential that will trigger the cleaning process.  Typically this is 7 – 10 psid.

Q?How fine a disc should be selected?

The nature of the solids to be removed and the desired result of the filtered will determine the disc to be selected.  Remember over filtration can be expensive in extra power used for finer filtration and water used in the cleaning process.

Q?What is the difference between a Multi Groove (MG) and a Wall Disc (W)?

The Multi Groove Disc MG,
• flat ring,
• grooved on both sides and made of different plastics.
• Best suited for a depth filtration. 3D filtration
The Wall Disk W,
• flat ring,
• with different geometry and functionality on both sides injected plastics.
• The filter element includes a stack of disks arranged in such a way that the contiguous faces of two discs are “opposing” each other.
• disks are particularly suitable to retain large volumes of solids present in the water being filtered.  (Very large surface area)
• 2D Filtration

MG disks perform depth filtration whereas  the W discs are more like a screen filter.  W discs decrease the backwashing  frequency. The W discs can handle a lower quality of water.  MG discs provide a higher quality of filtered water as a result of the depth filtration.  Both types of discs are effectively cleaned during the backwash cycle.

Q?What parameters define water quality?

The nature of the pollutants (solids) – Organic or inorganic.
Particle Count (number of particles in a given volume)
Particle Size (distribution of particle sizes in a given volume)
Particle Volume (How much space do the particles take)

(Total Solids = Total Dissolved solids + Total Suspended Solids)

Q?What are the advantages of an AZUD DISC filter over screen filters?

The Azud disc filter can be used for organic and in-organic particle filtration. (Organic material needs to be consdered when using screen filters, as these can be captured and stick in the screen making cleaning very difficult).
Discs completely clean in a backflush cycle.
Flow to the system is uninterupted during backwash.
Plastic has high resistance to wear.
Helix system keeps heavier and larger particles away from the disc surface, prolonging period between cleaning cycles.

Q?What is the advantage of a disc filter over a sand media filter?

The Azud disc filter can be used for organic and in-organic particle filtration.  (Size and weight of in-organic material needs to be consdered when using sand media filters).
Significantly less water used to backwash.