Advanced Coalescing Filtration Technology
Freudenberg Filtration Technologies manufacture Coalescers for refrigeration applications.
The Microfresh® range of coalescers are specifically designed for the industrial refrigeration industry using ammonia and other refrigerants.
Oil aerosols emitted by ammonia refrigerant compressors are under 5µm particle size and the majority are smaller than 2µm.
Other contaminants in the refrigeration system are solids consisting of rust and scale that are typically between 5µm and 0.5µm particle size. These can clog the coalescing media, shortening the life of the compressor as well as the coalescer.
The oil filter plays an important role in the operation of the coalescer by minimising the amount of solid particles circulating, thus allowing the coalescer to do it’s job in removing oil aerosols.
Early coalescing filters were expensive and caused high pressure drop.
Technology used in the manufacture of glass fibre and the latest studies of aerosol behaviour have led to the development of microfibre glass and graded porosity filter media giving much higher filter and coalescing efficiency.
Early elements could remove particles down to 2µm, but graded porosity microfibre glass are able to remove particles as small as 0.001µm.
Three mechanisms of the coalescing process
Diffusion - 0.01µm to 0.2µm
Interception - 0.2µm to 2µm
Direct Impact - 2µm and larger
Filter efficiency and pressure drop
Filter efficiency is important because it affects not only contaminant removal but also the filter life.
Pressure drop is the first indication of the coalescer failing. It signals that the filter is becoming blinded and the flow is reduced. Flow rate, operating pressure, the volume of contamination and the type of contaminant in the stream all affect the rate of pressure loss across a coalescing filter.
When a pressure drop of between 2 kPa (8 in H2O) to 2.5 kPa (10 in H2O) is indicated the coalescer should be replaced.
Microfresh® Refrigeration Oil Filter - Flow Restriction Graph
Microfresh has been a major supplier of these filters to the Australian market since 1990
Freudenberg Filtration Technologies | Microfresh® Industrial Filtration Coalescers Australia.