What are filter bags and where can they be used?
Filter bags are designed to purify water and remove particulates such as silt, sediment, sand and dirt from different types of liquids. Commonly made from polypropylene and polyester felt, the filter bag is attached with a sturdy ring at the opening that creates a seal between the bag and its external casing, designed to prohibit any pollutants and other harmful particles from passing through the liquid. In addition to water, filter bags can be used to purify other liquid mediums such as alcohol, petrol, vegetable oils, biodiesel, weak acids and alkalis, organic solvents and microorganisms.
How does a filter bag work?
As the filter bag fills with water, the particles penetrate through the pores and are captured in the depth of the filtration mechanism, allowing the pure water to filter through and leave the unwanted particles behind. The size of the water filter determines the efficiency of the filtration process – this is denoted in microns, which range in ratings from 1-100. The smaller the micron size of the water filter, the higher the efficiency of the filtration.
The micron size required depends on the type of water purification required, as some filter bags have a micron rating that is small enough to filter out some particulates, but is not effective in removing certain types of bacteria or chemicals. One micron is required for the removal of bacteria and cysts (which have an average width of 0.2 to 2 microns and a length of one to 10 microns), although it is still advisable to use a chemical such as chlorine to kill bacteria.
The length of time that the filter bag is in use depends on the liquid that you are filtering – for instance, filtering mud would only last a few minutes, whereas the filtration of clean water could last for a year. In terms of bag filter maintenance, when the pressure starts to raise faster, this is an indicator that the bag is almost used up and should be changed. It is therefore recommended that the bag is changed when the 8-12 PSI pressure drops (this is the difference in pressure between the filter’s inlet and outlet).
What are the benefits of using filter bags?
With a high flow rate and a superior debris holding capability, filter bags can absorb both non-deformable and deformable gelatinous particles of varying sizes. When in use, filter bags can also increase the efficiency of the water system’s filtration mechanism and its ability to clean.
- Micron ratings available from 1 to 100µm
- Double integral handles
- Ring diameter: 178mm (7”)
- Bag length: 433mm (17”)
- Maximum operating temperature: 135°C
- Maximum differential pressure: 4 Bar
Multi-purpose polyester needlefelt filter bags are available to purchase in packs of 10. SOCOTEC offers filter bags in the following part numbers:
*For ease of reference, the PE section stands for polyester filter bag, while the first number equates to the rating of the micron. The second set of numbers and letters (e.g P1) relates to the size of the filter bag, while the final letter (S) is the size of the outer ring.
Please note that filter bags are designed for a one time use and are not suitable for reuse. They are also only designed to operate to the recommended maximum temperature of 135 degrees Celsius.
The water filter bags are available for purchase via credit/debit card, Apple Pay or Google Pay. Please contact us if you would like to pay by bank transfer or raise a PO.
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