Compressed Air & Gas Filters

High Temperature Filter

Clean air right where the heat is used, with seals and housings that hold through every heat-up and cool-down.

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Two stainless steel high temperature filter housings

Product overview

Particle-free air at the temperature your process runs

Our high temperature filter removes solid particles from compressed air and technical gases that flow hot: air used before it is aftercooled, air raised in temperature by a process heater, and lines running through furnace halls, glass forming lines and boiler houses.

It is rated for continuous service commonly up to about 200 °C, with specialised designs rated higher. The element, seals and housing keep their filtration efficiency, sealing integrity and pressure rating at that temperature and through repeated heating and cooling. The general-purpose 1 µm grade removes pipe scale, rust, carbon and wear debris; the high-efficiency 0.01 µm grade removes sub-micron dust to protect fine nozzles, analysers and sensitive processes.

Hot air normally carries its water as vapour, so the filter collects dry dust that stays loose and porous on the element, as long as every internal surface stays above the dew point.

A high temperature filter housing beside its filter element
  • About 200 °CContinuous service, common rating
  • 0.01 µmHigh-efficiency grade
  • 1 µmGeneral-purpose grade
  • About 2.3 ×Clean pressure drop at 200 °C against 20 °C

Benefits

The problems it solves

A hot line produces particles continuously, even pipework that was clean at commissioning. Here is what they do, and how the filter stops them.

  • Scale from hot pipework

    The problem

    Each heating and cooling cycle breaks flakes of oxide scale away from steel pipes and heater surfaces into the air stream.

    How it solves it

    Filtering at process temperature, after the heater and hot pipework, catches the scale they add before it reaches your process.

  • Blocked jets and scored valves

    The problem

    A single scale flake can block a small bore and stop a sealing, drying or cooling jet, and hard oxide particles score valve seats.

    How it solves it

    Nozzles, valves, desiccant, catalysts and analysers stay free of scale and carbon, so blocked jets and scored valves no longer stop production.

  • Seals that fail in the heat

    The problem

    At high temperature elastomers harden and take a permanent set, opening a leak path around the element that lowers the pressure drop instead of raising it.

    How it solves it

    Element and housing seals rated for the temperature hold through heat-up, steady running and cool-down, so no air bypasses the medium.

  • A particle class you must meet

    The problem

    A specified ISO 8573-1 particle class applies to the air that reaches your process, whatever its temperature.

    How it solves it

    The air can meet your specified ISO 8573-1:2010 particle class at the point of use.

  • Housings beyond their rating

    The problem

    Metal strength falls as temperature rises, and a pressure rating is valid only up to its declared temperature.

    How it solves it

    Housings carry declared pressure and temperature ratings under PED 2014/68/EU or ASME, for safe containment at temperature.

  • Spoiled test results

    The problem

    Debris entering a turbine or turbocharger under test damages blades and invalidates results.

    How it solves it

    Test articles receive debris-free air, so failures reflect the article under test, not contamination.

Where it’s used

Wherever your air runs hot

Near furnaces, kilns and boilers, and wherever compressed air is heated for the process, the filter works at the temperature of the air it protects.

  • Glowing glass bottles being formed on a production machine

    Glass

    Plant air lines beside furnaces and forming machines, where surroundings stay hot and pipework runs hot.

  • Molten metal pouring from a ladle in a foundry

    Steel, aluminium and foundries

    Air supplies near furnaces, ladles, continuous casters and rolling mills that carry oxide scale.

  • A worker pouring concrete over steel reinforcement

    Cement, lime and minerals

    Air lines in kiln and clinker cooler areas, exposed to radiant heat and heavy dust.

  • Electricity pylons and power lines at sunset

    Power generation

    Air and gas lines held at elevated temperature in boiler houses and turbine halls.

  • Test tubes of coloured chemicals in a laboratory rack

    Chemicals and petrochemicals

    Hot nitrogen purging of reactors, catalyst regeneration air and hot process gas streams.

  • Blue plastic bottle caps in a moulded tray

    Plastics and packaging

    Hot-air welding, heat sealing and shrink processes, where particles mark the product surface.

Also heat-of-compression desiccant dryers, emissions and process gas analysis, aerospace and automotive test rigs, electronics soldering and rework, and compressor heat recovery.

How it works

Filter hot, seal tight, stay dry

The filter sits after the last source of particles and before the equipment it protects, at the temperature of the process it serves.

How a high temperature filter works: dry air is heated in a process heater and carries oxide scale into the insulated filter. The hot air flows down around the element and passes from outside to inside through the depth medium, which holds the scale and dust on its outer surface. Temperature-rated seals stop air bypassing the medium, the clean hot air rises up the core to the outlet, and the insulation keeps every surface above the dew point. Dry airProcess heaterUp to about 200 °C Clean hot air out Differential pressure gauge Scale caughton the outside Temperature-rated seal InsulationjacketAbove ≈ 55 °C dew point Temperature-rated drain Inside the mediumInterception · ≈ 0.3–1 µmImpaction · above ≈ 1 µmDiffusion · below ≈ 0.1 µmSieving · scale flakes 12345Hot air carrying scaleClean hot airDry supply airCaptured scale and dustInsulationTemperature-rated seal

  1. 1. Hot air inAir heated at the point of use carries oxide scale from the heater and hot pipework. It enters the filter head and is directed into the bowl around the outside of the element.

  2. 2. Outside to insideThe air passes from the outside of the element to its inside. Scale and debris collect on the outer surface and in the depth of the medium, caught by sieving, impaction, interception and diffusion, and the dry dust builds an open, porous layer.

  3. 3. Sealed at temperatureElement and seal materials rated for the temperature, and a seal geometry that keeps contact pressure through each thermal cycle, stop any air bypassing the medium.

  4. 4. Clean hot air outThe clean air rises through the element core and leaves through the outlet, to a hot-air point of use as close to the filter as practical.

  5. 5. Kept above the dew pointInsulation keeps every internal surface above the pressure dew point, so no liquid wets the dust. The temperature-rated drain discharges anything that falls to the bowl, and the gauge reading is compared with a baseline taken at operating temperature.

Dew point of about 55 °C for air drawn in at 25 °C and 60 % RH and compressed to 7 bar g.

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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