Coalescer Filters

coalescer products

Advanced Coalescing Filtration Technology

Freudenberg Filtration Technologies manufacture Coalescers filters for refrigeration applications.

The Microfresh® range of coalescers filters 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 filter.

The oil filter plays an important role in the operation of the coalescer filter by minimising the amount of solid particles circulating, thus allowing the coalescer filter 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 filter 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 filtration process

coalescing process diffusion

Diffusion - 0.01µm to 0.2µm

coalescing process interception

Interception - 0.2µm to 2µm

coalescing process direct impact

Direct Impact - 2µm and larger


Filter efficiency and pressure drop

Coalescer 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 filter 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 filter should be replaced.

Microfresh® Refrigeration Oil Filter - Flow Restriction Graph

filter efficiency and pressure drop

filter efficiency pressure drop legend

Microfresh has been a major supplier of these Coalescer filters to the Australian market since 1990

Freudenberg Filtration Technologies | Microfresh® Industrial Filtration Coalescers Australia.