Water Filter

 ▶  A water filter removes impurities from water by means of a fine physical barrier, a chemical process or a biological process.
      Filters cleanse water to various extents for irrigation, drinking water, aquariums, and swimming pools

 ▶  Filters use sieving, adsorption, ion exchanges and other processes. Unlike a sieve or screen, a filter can remove 
      particles much smaller than the holes through which the water passes  

     - Fresh water filters need cartridges made of steel grid and with holes bored in it

    - it requests finer net (0.1-0.5mm) over the holes

    - Sea water filters are also made of steel tin but with rough net placed over the holes

    - diameter of the holes is from 1 to 3mm

(Multi-cartridge housings)

※ Types of filters

   • Water filters

   • Air filters

   • Fuel filters (DO & HFO)

   • Lube oil filters

   • Hydraulic filters

   • Fine filters (magnetic)

  Filtration Basics

 ♦ Materials : polypropylene, Stainless steel(316), activated carbon media, Resin bonded glass fiber, Resin bonded 
                   cellulose filter...etc

 (Activated Carbon & Ceramic Filter)

 ♦ Dimensions : 

   • In diameter :  28mm/30mm/25mm/113mm ... etc

   • Out diameter : 62 - 67mm, 150mm ... etc  

   • Length  :  250mm, 10-40 inches ... etc
 

 ♦ Grade : 1micron - 80micron ... etc
 

 ♦ Filtration Grading : NOMINAL, ABSOLUTE

   • Nominal rating the filter removes about 90% of particles of a specified  size

   • Absolute rating the filter removes 99.9% particles of a specified size. (Essentially All)

 
 ♦ Filtration type : Surface vs. Depth Filtration…

   • Surface type traps particles on surface as shown - typically cleanable

     -  Greater surface area

     -  Higher flow rate

     -  NOT SUITABLE for cyst reduction less filtration integrity

     -  Most commonly used as a prefilter e.g. 20㎛ to extend the useful life of a finer depth filter

   • Depth type traps progressively through cartridge - typically not cleanable

     -  Lower surface area

     -  Lower flow rate

     -  SUITABLE for cyst reduction more filtration integrity

     -  Need 20Psi (140kPa) pressure

     -  Often used as finer filters 

  Type of Water filter 

 ♦ Cartridge filter : Depth Type Filter,  Surface Type Filter,  Wound Type Filter, Pleated Type Filter ... etc 

   • Depth-type filter
     - Depth type traps progressively through cartridge - typically not cleanable 
     - depth-type filters capture particles and contaminant through the total thickness of the medium, while in surface
        filters (that are usually made of thin materials like papers, woven wire, cloths) particles are blocked on the 
        surface of the filter.

(Depth-type filter)

   • Surface type filter : Pleated Type Filter...etc
     - Surface type traps particles on surface as shown - typically cleanable

     - Surface filters are best if you are filtering sediment of similar-sized particles. If all particles are i.e. five micron,
       a pleated 5-micron filter works best because it has more surface area than other filters. Compared with pleated
        surface filters, depth filters have a limited surface area, but they have the advantage of depth.

(Pleated Type Filter)

  ♦ Applications

    •  Pre- RO desalination,  water purification, semiconductors, often used as final filtration ... etc

  AIR filter (Bag filter)

   ♦ Multiple layers for better cleaning

   ♦ Air filters are used in applications where air quality is important, notably in building ventilation systems and in the 
      engines.

 Filter problems

   ♦ Pressure drop