SERIES 5: Reticulated Polyurethane Air Filter
At the heart of the FCL long life air cleaner is a multi-layered, fully reticulated, polyethylene foam media. The filter is constructed with open porosities on the outside of the filter acting as a pre filter capturing larger debris and not allowing them to block the inner layers which capture particles down to 5 microns. This allows the air to flow freely through the outer layers offering a much lower pressure drop when compared to a filter of paper construction, whilst offering a much larger capacity and 99.7% efficiency.
There are now two recognized standards in Filtration media. They are:
- Pleated Paper
- Reticulated Polyurethane
Although the basic construction to these elements are similar, the performance characteristics and benefits are extremely different.
Under test facilities, an element is tested under constant airflow and high dust concentrations, where dust will quickly build up on the surface and become an integral part of the filter. However, in real life situations the airflow is variable due to the change in the engines RPM. This will give a considerably different set of results as dust build up is much slower and vehicle vibration will shake the dust off the surface. This gives the effect of prolonging the low initial efficiency of the paper for much longer. If the filter is being changed too regularly then the engine is not being protected to the same standards as if the filter was left in as long as possible.
Premature failure can be experienced with pleated paper as hydrocarbons (exhaust fumes) can quickly block the surface, causing a rapid increase in the restriction on the filter.
Also, damp conditions can cause the paper to swell, blocking the pores and increasing the restriction. Continual running in damp conditions causes the paper to swell and contract due to the drying out effect of the airflow, leading to the cracking of the paper at the base and tip of the pleat. As a result of this, all protection to the engine will be lost.
These elements are made from 3 to 5 layers of different porosities starting open / coarse porosity on the outside to a virtually closed / fine porosity on the inside. The polyurethane layers are like an ever tightening honeycomb that grades the particles from the course to fine as the air passes through the filter. This is known as a depth media.
To achieve high levels of efficiency required to protect an automotive engine, the polyurethane has to have a special additive coated on to the surface of the strands of polyurethane. This is so that the dust particles can stick to the polyurethane and become part of the filter. The particle will then soak up the additive and become wet allowing further dust particles to stick to it. This is known as wetting.
The initial efficiency of a polyurethane element is considerably higher than that of a paper element and will offer greater protection for most of it’s life than a paper filter.
Under test conditions of constant flow and high dust concentrations, the polyurethane air cleaner will not achieve as much dust holding as in real life, because the wetting process is not achieved due to the short time scale that the test is carried over. Vibration of the vehicle will not effect the efficiency of the polyurethane element as the dust is permanently bonded to the polyurethane.
Hydrocarbons will not prematurely fail a polyurethane filter as it is easily absorbed into the matrix of the polyurethane. Due to the plastic construction of the filter, it is totally unaffected by water and in damp conditions will retain maximum protection.
Main Engine Train Foam Filters
As we are designers, manufacturers and suppliers of the Blue Diamond range we have agreements with Bombardier which enable us to supply direct into the rail industry worldwide.
We pride ourselves on offering a complete service to our customers, not only in supplying all of their filter needs but acting as their ‘filtration division’, a One Stop Shop, supporting customer visits, research and development of filters that meet the specific needs of the customer or applications.
By incorporating this expertise we have been developing a ‘Long Life’ family of air filters for Bombardier, this being called the ‘Blue Diamond’. The Blue Diamond filter range includes main engine air filters, Heating Ventilation and Air Conditioning (HVAC), compressor intake etc.
Key Advantages of Reticulated Polyurethane Filters
- Significantly greater filter life
- Greater efficiency
- Developed in conjunction with Mira since 1980
- Not affected by carbon and moisture
- Used by the vast majority of the UK bus industry with current production requirements running at over 1500 units per week
- Available in multi-stage “5 series”
- Initial cost on many types, is less expensive than good quality paper filters
- Reticulated polyurethane produced within ±2 pores and reticulated by gas blown method, NOT chemically
- Outer layers have patented dimple profile
- All filters treated synthetic plasticiser
- Full test and backup facility available in our in-house test laboratory
- All filters and engines covered by FCL unconditional warranty
FCL filters are guaranteed to be free from any defect in workmanship and materials during the service life recommended and if found to be defective will be replaced .Vehicle and engine warranties cannot be voided solely due to the use of FCL filters. This warranty does not cover failures caused by misuse, faulty installation, alteration, or accident. In the event of engine failure directly attributable to a FCL filter defect ,FCL will restore the engine to a condition equivalent to that existing just before the failure. However, FCL is not liable for any other losses or expenses incurred due to such defect.