Compressed Air & Gas Dryers

Refrigerated Air Dryer

Dry, dependable air across your whole plant, without spending a drop of compressed air to make it.

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A refrigerated air dryer cabinet with its control panel and condenser grille

Product overview

Dry air for your plant, without spending compressed air to make it

Our refrigerated air dryer cools your compressed air until its excess water vapour condenses, separates and drains that water away, then rewarms the air before it leaves. It delivers a pressure dew point as low as +3 °C, so no liquid can form anywhere your network stays warmer than that, which covers most indoor systems.

Air saturated at 35 °C and 7 bar g carries about 5.3 kg of water an hour for every 1,000 m³/h of free air. The dryer takes out about 87 % of it, roughly 110 litres of condensate a day at continuous full load, and discharges it through an automatic drain.

With a general-purpose filter upstream and a high-efficiency coalescing filter downstream, it forms the core of a system delivering ISO 8573-1 Class 1:4:1 or 2:4:2 air, for general manufacturing, instrument air in heated buildings and indirect food contact.

Two refrigerated air dryers of different sizes side by side
  • +3 °CPressure dew point
  • Class 4ISO 8573-1:2010 water class
  • About 87 %Of the water removed at the dryer
  • ZeroCompressed air used for drying

Benefits

The problems it solves

Compressing air packs its water in with it. Here is what that water does to a plant, and how the dryer stops it.

  • Rust in your pipework

    The problem

    Rust flakes from wet pipework block orifices, jam valve spools and score cylinder bores.

    How it solves it

    Pipework above +3 °C stays free of condensate all year, so your steel network stays free of internal rust.

  • Worn seals and tools

    The problem

    Condensate strips grease from cylinder seals and air tools, raising friction and wear.

    How it solves it

    With the water taken out at the dryer, your valves, cylinders, instruments and tools keep their lubrication and last longer.

  • Spoiled product

    The problem

    Water droplets cause fisheyes and blistering in paint, spotting in blow-off and stains on yarn and fabric.

    How it solves it

    No liquid can form in a network kept above +3 °C, so none reaches your point of use.

  • Drains all over the plant

    The problem

    Drip legs and low-point drains spread across the network, venting compressed air when they fail.

    How it solves it

    Water and coalesced oil leave through one drain at the dryer, piped to your oil–water separator.

  • Sweating pipes

    The problem

    Cold, dried air makes pipework sweat on the outside in a humid compressor room or production hall.

    How it solves it

    The dryer rewarms the air before it leaves, so your pipes stay dry outside as well as in.

  • Audits and warranties

    The problem

    Customers, auditors and machine warranties name the air quality class you have to meet.

    How it solves it

    A dew point reading at the outlet documents ISO 8573-1 Class 4 for audits and customer specifications.

Where it’s used

Wherever plant air runs indoors

Most plant air runs through heated buildings where pipes stay above 10 °C all year. That is exactly where a +3 °C dew point keeps the whole network dry.

  • Robots welding a car body on an assembly line

    Automotive and engineering

    Assembly tools, robotic grippers, machine tool clamping and spindle air, and paint shop supply.

  • Wine bottles moving along a bottling line

    Food and beverage

    Air in indirect contact with food, such as packaging machinery and actuators, to BCAS Guideline 102 Class 2:4:2.

  • A row of yarn winding machines in a textile mill

    Textiles

    Air-jet looms, texturising and splicing, where condensate stains yarn and fabric.

  • Blue plastic bottle caps in a moulded tray

    Plastics

    Injection moulding robots, mould ejection and blow moulding pilot air.

  • Yellow tablets spilling from a medicine bottle

    Pharmaceutical utilities

    Plant air for valve actuation and services that do not touch the product.

  • Test tubes of coloured chemicals in a laboratory rack

    Process plant instrument air

    Instrument air in heated buildings where pipework stays at or above 13 °C, meeting ISA-7.0.01.

Also general manufacturing, packaging and printing, woodworking and furniture, workshops and garages, hospitals and laboratories, and pre-drying ahead of desiccant dryers and nitrogen generators.

How it works

Cool, separate, rewarm

A closed refrigeration circuit chills your air until its water condenses out. The dry air is then warmed back up before it reaches your pipework.

How a refrigerated air dryer works: wet air is pre-cooled in an air-to-air heat exchanger, chilled to +3 °C in the evaporator, its water separated and drained, then rewarmed in the same heat exchanger before it leaves. A refrigerant compressor, condenser and expansion valve keep the evaporator cold. Wet air in35 °C · saturated Dry air out≈ 25 °C · PDP +3 °C Air-to-air heat exchanger ≈ 21 °C Evaporator +3 °C MoistureseparatorAutomatic drainCondensate out Expansion valveCondenserRefrigerant compressorHeat out 12345 Warm, wet compressed air Chilled air, at +3 °C Dry air, rewarmed Condensate Hot refrigerant Cold refrigerant

  1. 1. Pre-coolWarm, saturated air at 35 °C enters the air-to-air heat exchanger and is cooled to about 21 °C by the cold, dry air leaving. About 60 % of the condensate already forms here.

  2. 2. ChillIn the evaporator, boiling refrigerant cools the air to about +3 °C, and the rest of the surplus water vapour condenses into droplets.

  3. 3. Separate and drainThe moisture separator throws the droplets out of the air, and the automatic drain discharges them.

  4. 4. RewarmThe cold, dry air passes back through the heat exchanger and leaves at about 25 °C. Its water content is unchanged, so its dew point stays at +3 °C while its relative humidity falls to about 24 %.

  5. 5. The refrigeration circuitThe refrigerant compressor raises the refrigerant's pressure, the condenser rejects the heat to ambient air or cooling water, and the expansion valve drops the pressure so the refrigerant boils in the evaporator again. The evaporator is held just above freezing, so the condensate never turns to ice.

Typical figures at 7 bar g, with saturated inlet air at 35 °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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