A bag filter system is one of the most popular filtration methods for liquid process applications. It provides a versatile, cost effective and consistent filtration system suitable for a broad range of applications from small batch operations to bulk processing. Bag filter housings are available in a wide range of materials and sizes, and can handle any fluid types and flow rates in the range of 1m3/hr to in excess of 300m3/hr. Replacement filter bags are selected from the broadest possible range of media. The required filter media is determined by the size of the particles to be removed (0.5 – 1500 microns), the type of particles to be removed (deformable or non-deformable), the required retention efficiency (60% to >99%) and the chemical and temperature compatibility of the media.
Standard Filter Bag Overview
Allied Filter Systems Ltd manufactures high quality liquid filter bags to fit standard size filter vessels, as well as custom designed products where requested. The constituent materials have been chosen for their purity, consistent high quality and repeatable performance.
Sewn Needlefelt Filter Bags
Traditional sewn needlefelt filter bags are a versatile and cost effective media providing a high solid holding capacity for both non-deformable and deformable, gelatinous particles. By means of a depth filtration mechanism, particles penetrate and are captured throughout the depth of the filter media.
Fully Welded Filter Bags
All seams are welded rather than sewn, and combined with our positive sealing moulded Welseal (polypropylene or polyester) welded ring, no process liquid can bypass through needleholes caused by the sewing process or around a traditional metal ring.
Mesh Filter Bags
Mesh filter bags provide surface filtration – a ‘sieving’ mechanism, causing particles larger than the pore size of the media to be captured on the surface of the media. They are excellent for removing non-deformable, solid particles and have no fibre migration.
Custom Made Filter Bags
For unique applications requiring liquid filter bags which fall outside of the scope of our standard range, our manufacturing flexibility and expertise enables us to design and produce custom made products which perfectly meet our clients needs.
Food & Pharmaceutical Grade Filter Bags
Bag filters, when used in food, beverage or pharmaceutical applications, must conform to specific standards such as EC directives or FDA. Migration limits of contaminants from polymers into a food product have been imposed, and independent testing and certification of component materials is required to ensure these regulations are satisfied. Stringent testing, manufacturing and packaging conditions are also required to eliminate other sources of contamination.
Extended Life Filter Bags
Increased thickness of the graded filter media compared to that of the equivalent standard felt filter bag results in increased retention of particles. In addition, the extended life filter media has a graded density structure i.e. progressively smaller particles are captured as the fluid follows a tortuous path through the media, stopping the filter bag from blinding prematurely. The result is a filter media with a higher dirt holding capacity, leading to increased filter bag lifetime.
Multi Layer Felt Filter Bags
Multi Layer felt filter bags provide graded density, multi stage depth filtration in a single filter bag. A high dirt loading capacity and superior filter bag lifetime is achieved by selecting the optimum micron ratings of the pre-filtration and final filtration layers in accordance with the needs of the filtration process. Multi Layer filter bags can be produced with 2 or 3 layers of polypropylene or polyester needlefelt, and to further enhance performance, a layer of extended life felt can be incorporated. An optional mesh exterior cover can also be provided.
Mega Depth Series
The Mega Depth multi-layered filter bag range has been developed to optimise filtration efficiency, lifetime and dirt holding capacity in either a continuous or batch process. The constituent filter bag layers are customised and selected to meet the needs of the specific application, giving a filter bag which optimises the filtration process.
High Capacity Filter Bags
Newly installed filter bag housings or existing systems can utilise High Capacity filter bags, which increase the filtration surface area by 70% compared with a similar sized standard bag.
The High Capacity baskets can be supplied to retrofit existing standard size filter bag housings.
MBP 200 Series High Efficiency Filter Bags
The MBP 200 Series high efficiency bags are available rated at 1-25 micron, and perform to efficiencies >95%. The filter bag consists of up to 4 layers of melt blown polypropylene media. The high density of small diameter fibres compared to that of a standard needlefelt enhances particle retention, leading to superior, highly efficient filtration.
MBP 300 Series High Efficiency Filter Bags
The MBP 300 Series is a unique range of absolute rated filter bags rated from 1 – 10 micron, performing to an efficiency of >99% at the stated micron rating. This series provides a viable alternative to applications where filter cartridges have previously been the method of choice.
OA Series Filter Bags
The OA Series filter bags have a high oil and hydrocarbon absorption capacity, and are available rated at 1-25 micron with particle removal efficiencies >90%.
Oil Absorption Insert
The oil absorption insert is positioned within a standard filter bag, which can be any single layered type selected in accordance with the particle retention needs of the process.
High Efficiency Filter Bags – 500 series
The 500 Series filter bag contains in excess of 5m2 of materials, and provides a very high oil and dirt holding capacity at high efficiency. It is constructed from 100% meltblown polypropylene microfibre filter media, giving a broad chemical compatibility.
WA Series Filter Bags
The water absorbent (WA) series is used for processes requiring water removal from hydrocarbons.