Compressed Air & Gas Filters

High Pressure Filter

Documented air purity at full pressure, from 40 bar g blow moulding to 300 bar g cylinder filling.

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A blue high pressure filter housing with its drain valve

Product overview

Clean air and gas where the pressure is highest

Our high pressure filter removes solid particles and water and oil aerosols, and in its carbon grade oil vapour and odours, from compressed air and technical gases held well above plant-air pressure. Duties start at about 20 bar g and run to 350 bar g and beyond: 40 bar g PET blow moulding air, 25–30 bar g marine starting air, and 200–300 bar g breathing air and gas cylinder filling.

At these pressures the gas behaves differently. At 40 bar g and 20 °C air weighs about 49 kg/m³, and at 350 bar g roughly 370 kg/m³, about 40 % of the density of water. The filter is engineered around this: slow gas through the media, and drops that drain against a dense gas that partly buoys them.

Grades cover general-purpose and high-efficiency coalescing, dry particulate and activated carbon, tested under the ISO 12500 series and expressed against the purity classes of ISO 8573-1:2010. The housings are designed and certified as pressure equipment and pressure tested before release.

A tall high pressure filter housing beside its filter element
  • 350 bar gDuties up to, and beyond
  • About 0.01 µmHigh-efficiency coalescing grade
  • Under 1 %Of operating pressure lost at 40 bar g, clean element
  • PED 2014/68/EUOr ASME Section VIII pressure equipment

Benefits

The problems it solves

Compressing air to 300 bar g packs about 300 volumes of it into one, together with everything it carries. Here is what that concentrated contamination does, and how the filter stops it.

  • Marked bottles and tainted drinks

    The problem

    Oil droplets in PET blow air mark bottles and transfer taste to beverages.

    How it solves it

    PET containers stay free of oil marks, with the filter train forming part of your documented route to BCAS Guideline 102.

  • Unsafe breathing air

    The problem

    Oil mist and hydrocarbon vapour in breathing air irritate the lungs of divers and firefighters working under exertion.

    How it solves it

    Coalescing and carbon grades form part of your documented route to EN 12021:2014, which limits oil to 0.5 mg/m³.

  • Leaking valves and frozen regulators

    The problem

    Particles score the soft seats of high pressure valves, and moisture expanding through a regulator freezes in its seat.

    How it solves it

    Particle-free, liquid-free gas keeps your soft seats sealing and prevents regulator freezing caused by liquid water.

  • Fouled dryers and carbon beds

    The problem

    Oil aerosol blocks the pores of desiccant and activated carbon permanently.

    How it solves it

    Oil-free, liquid-free feed preserves the capacity of the dryer and carbon stages that must meet your water and vapour limits.

  • Corroded cylinders and receivers

    The problem

    Water collecting in cylinders and receivers corrodes the walls and reduces their certified service life.

    How it solves it

    Removing water and oil at the fill point stops internal corrosion and contamination of your cylinders and receivers.

  • Stored energy in the housing

    The problem

    A 1-litre volume of air at 350 bar g releases about 71 kJ if it expands suddenly.

    How it solves it

    Housings designed, certified and pressure tested as pressure equipment protect your people from the stored energy of high pressure gas.

Where it’s used

Wherever air works at high pressure

From bottle blowing to engine starting, high pressure duties need filtration rated for the pressure and proven at the point of use.

  • Wine bottles moving along a bottling line

    Beverage and food packaging

    PET stretch blow moulding at up to 40 bar g, where the air touches the inside of every container.

  • A naval warship at sea

    Marine

    Diesel engine starting air stored at 25–30 bar g, where water and oil corrode starting valves and oil-fouled pipes are an explosion hazard.

  • Electricity pylons and power lines at sunset

    Power generation and utilities

    High pressure air for circuit breaker mechanisms and black-start systems.

Also breathing air for diving, fire service and escape sets, cylinder filling of nitrogen, argon and helium, laser cutting, gas-assisted injection moulding, test and inspection rigs, offshore seismic survey, oil and gas, and research and defence.

How it works

Filtered at full pressure

The filter sits after the final aftercooler, where the air is at full pressure and its lowest temperature, so the aerosols have already formed and can be caught.

How a high pressure filter works: air leaves the high pressure compressor’s final aftercooler and separator at full pressure, enters the bolted, pressure-rated head and turns down into the core of the element. It passes outward through microfibre coalescing media, and the captured droplets drain against the dense gas into the sump. A pressure-rated drain valve discharges the liquid into a pressure-rated collection vessel, and the filtered gas leaves through the outlet. HPcompressorAftercoolerSeparator Filtered gas outUp to 350 bar g Pressure-rated bolted head Microfibrecoalescing media Draining in dense gasWeight pulls downDense gas buoys up≈ 37 % less at 350 bar g Pressure-ratedcollection vessel≈ 89 m/s at 40 bar g 12345Gas with oil and waterFiltered gasLiquid drained at pressureCoalescing mediaOil and water dropletsUpstream plant

  1. 1. After the final coolerAir leaves the high pressure compressor’s final aftercooler and separator at full pressure, enters the head and turns down into the hollow core of the element.

  2. 2. Through the mediaThe gas passes radially outward through the microfibre media. The dense gas moves slowly, and droplets and particles are caught by impaction, interception and diffusion.

  3. 3. Drain against dense gasCaptured droplets merge and grow in the outer drainage layer until gravity pulls them down to the sump. At 350 bar g the dense air reduces the net weight of a water drop by about 37 %, so the layer grows drops large enough to fall reliably.

  4. 4. Drain at pressureThe sump drains at full system pressure. Water leaves a drain orifice at about 89 m/s at 40 bar g, so the drain valve is built for this duty and discharges into a pressure-rated collection vessel.

  5. 5. Pressure-rated housingThe bolted head and bowl hold the full system pressure, while the element carries only the differential pressure across it. The gauge shows that differential, and the filtered gas leaves through the outlet.

Gas densities are quoted at 20 °C.

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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