Compressed Air & Gas Filters

Coalescing Filter

Catch the fine oil and water mist no separator can, and keep it out of every valve, tool and product your air touches.

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A blue coalescing filter housing with a differential pressure gauge on its head

Product overview

Oil-free, liquid-free air, right where your process needs it

Your compressed air carries liquid in a form no separator or receiver can remove: a mist of oil droplets mostly below 1 µm from the compressor, a fog of water from the aftercooler, dryer and pipework, and hydrocarbon aerosol drawn in from the air around your plant. Our coalescing filter collects it in a dense bed of fibres, merges it into drops large enough to drain, and sends it to an automatic drain.

The general-purpose grade removes particles down to 1 µm and reduces oil aerosol to about 0.5 mg/m³. The high-efficiency grade, installed after it, removes particles down to 0.01 µm and reduces oil aerosol to about 0.01 mg/m³. Oil removal is tested under ISO 12500-1.

The same filters clean nitrogen, carbon dioxide, natural gas and biogas, removing compressor lubricant, glycol and hydrocarbon condensate.

Coalescing filters of different sizes side by side
  • 0.01 mg/m³Oil aerosol, high-efficiency grade
  • 0.01 µmParticle removal, high-efficiency grade
  • 99.67 %Of the oil aerosol removed, in a 3 mg/m³ example
  • 12 monthsElement change interval

Benefits

The problems it solves

Even an oil-free compressor delivers air carrying hydrocarbons and water. Here is what that mist does in a plant, and how the filter stops it.

  • Gummed valves and instruments

    The problem

    Oil and water mix into a sticky emulsion that washes lubricant from cylinder seals, gums valve spools and narrows the orifices in positioners and transmitters.

    How it solves it

    Oil aerosol taken down to about 0.01 mg/m³ keeps your cylinders, valves, tools and positioners free of gumming, washout and blockage.

  • Spoiled finishes and products

    The problem

    Oil on painted, coated or bonded surfaces stops adhesion, and oil in air that touches food or medicines is a direct contaminant.

    How it solves it

    Painted, coated, packaged and moulded products stay free of oil defects.

  • Fouled dryers and generators

    The problem

    Oil permanently reduces the capacity of desiccant, activated carbon and nitrogen generator media.

    How it solves it

    Removing oil before it deposits lets your desiccant, carbon and nitrogen generation media last their full service life.

  • A filter that fills up

    The problem

    A filter that stores what it catches would soon be saturated with oil and water.

    How it solves it

    Captured liquid drains away as it forms, so the filter keeps working continuously between element changes.

  • Standards you must meet

    The problem

    Food, medical, breathing air and instrument air standards all set an oil limit, from 0.01 mg/m³ for direct food contact to 0.5 mg/m³ for breathing air.

    How it solves it

    The filters provide the oil and particle removal these standards demand, with ratings tested under ISO 12500-1 as a defined basis for your specification.

  • Energy lost to pressure drop

    The problem

    A saturated element holds back pressure the compressor must make up, and every bar of extra discharge pressure raises compressor energy by about 7 %.

    How it solves it

    A clean, correctly selected element holds a small pressure drop, and an annual element change keeps it there.

Where it’s used

Wherever oil in the air would do harm

Any process where air touches the product, feeds an instrument or protects further treatment needs the oil taken out first.

  • Wine bottles moving along a bottling line

    Food and beverage

    Bottle blowing, packaging, product conveying and aeration of mixes, where BCAS Guideline 102 sets Class 1:2:1 for direct food contact.

  • Yellow tablets spilling from a medicine bottle

    Pharmaceuticals

    Tablet coating, fluid-bed granulation and blister packing, where GMP audits require documented air quality.

  • A hand mixing paint in open tins of colour

    Spray painting and powder coating

    Where oil droplets cause cratering, fisheyes and poor adhesion.

  • Robots welding a car body on an assembly line

    Automotive

    Assembly tools, sealant dispensing and paint shops use filtered air throughout.

  • A row of yarn winding machines in a textile mill

    Textiles

    Air-jet looms blow air directly onto yarn, where oil stains the fabric.

  • Blue plastic bottle caps in a moulded tray

    Plastics

    PET blow moulding, where the air contacts the inside of the container.

Also medical and dental air, breathing air, instrument air, electronics and semiconductors, laser cutting, nitrogen generators, oil and gas, and CNG and biogas.

How it works

Capture, coalesce, drain

Droplets this small follow the air round every bend, so only a dense bed of fibres can catch them. The filter then turns the mist into liquid and drains it away.

How a coalescing filter works: oily, wet air enters the head and turns down into the core of the element, then passes outward through a bed of glass microfibres that catches droplets and particles. The droplets merge, run down the outer face into the bowl and leave through the automatic drain, while the clean air rises between element and bowl to the outlet. Oily, wet air inRated at about 20 °C Clean air out≈ 0.01 mg/m³ oil aerosol Differential pressure gauge Glass microfibrecoalescing media Inside the fibresInterception · ≈ 0.1–1 µmImpaction · above ≈ 1 µmDiffusion · below ≈ 0.1 µm Collectedoil and water Automatic drainOily condensate out 12345Oily, wet compressed airClean airOil and water drainedCoalescing mediaOil and water dropletsCaptured particles

  1. 1. Air entersOily, wet air enters the head and turns down into the open core of the element.

  2. 2. Capture in the fibresThe air passes outward through a deep bed of glass microfibres. Droplets and particles are caught by impaction above about 1 µm, interception from about 0.1 to 1 µm, and diffusion below about 0.1 µm.

  3. 3. CoalesceCaptured droplets merge into larger drops and are pushed to the outer face. There they run down the drainage layer and fall into the bowl.

  4. 4. DrainThe automatic drain releases the collected oil and water when the level rises. Route it to an oil–water separator, not a surface drain.

  5. 5. Clean air outThe clean air rises between element and bowl and leaves through the outlet. The differential pressure gauge shows when the element needs changing.

Ratings are stated at an inlet temperature of about 20 °C, for the high-efficiency grade.

Get the full details

Our brochure covers it in detail, and our questionnaire tells us what we need to recommend the right one for your plant.

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