UK designed and built by FlexEJ for optimal closed water system efficiency and direct value.

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Air & Dirt Separators

FlexEJ Air, Dirt and Air & Dirt Separators can be used in both heating and cooling systems. These robust and cost effective units are manufactured in our UK factory.


Air & Dirt Separators

What is an Air & Dirt Separator?

Air & Dirt Separators are used to remove air bubbles and dirt particles from HVAC piping systems...

  • Materials
    Carbon steel with PN16 flanges.
  • Application
    Heating water and cooling water services, not suitable for drinking water.
  • Rating
    10 Barg @ 110°C.
  • Web Shop
    Available online with next day delivery from our web shop.

How to select HVAC system equipment

1 What goes where?2 Low Loss Headers3 Air & Dirt Separators4 Dosing Pots5 Need something a bit different?6 Let us help
HVAC systems helpAll these products are designed to protect and optimise your heating or cooling system. These products are normally positioned as follows:
Air or Air & Dirt Separator ~ boiler flow lines.
Dirt Separator ~ boiler return lines.
Dosing pots ~ main flow and return.
Low Loss Headers ~ between the boilers and system.
HVAC Low Loss HeadersA low loss header decouples the boiler from the system. This allows the boilers/boiler circuit flow to optimise at best efficiency for any system conditions. FlexEJ low loss headers come with sensor ports on all four branches so whatever control system is being implemented you will have the port you need.
HVAC Air & Dirt SeparatorsThese separators keep the system clean with both dedicated and combined units. Air causes corrosion and in extreme cases pump cavitation or air locks. Dirt will reduce boiler efficiency over time and will reduce flow areas in all equipment. Removing both air and dirt will keep the system running efficiently and avoid costly maintenance.
HVAC Dosing PotsDosing pots are used to safely introduce inhibitors and other chemicals into the flowing system. Maintaining the correct water chemistry ensures all materials in the boilers, chillers and system are protected from corrosion.
HVAC something differentFlexEJ can design and build large, multi-circuit low loss headers to order. We can also offer low loss headers with air and dirt sections and all products in larger diameters for bigger systems. Please let us know what you need.
Let FlexEJ help Call our HVAC specialists on +44 (0) 1384 881188 or email us at or use Live Chat on this web site - we are here to help, please get in touch.

Can't see what you want? Need help?

Call us. Or use Live Chat.

For instant advice. We can custom-design and engineer almost any expansion joint you need for delivery in the UK or worldwide. Call our expert team on +44 (0) 1384 881188. Or email us

FlexEJ's Air & Dirt Separators:

FlexEJ's manufactures Air, Dirt and combined Air & Dirt Separators in the UK. They can all be bought direct from our web shop on a 24hr dispatch basis (Monday to Thursday). FlexEJ can also manufacture to meet specific client requirements, please get in touch.

Air Separators Dirt Separators
Air & Dirt Separators Custom fabrication options

FlexEJ Air & Dirt Separator


All products have:

  • Carbon steel body
  • PN16 flanges
  • DN25 drain ball valve

Air Sections - reduce system corrosion by removing air bubbles:

  • Flamco AAV with integral shut-off valve
  • Stainless steel internals

Dirt Sections - reduce dirt and sludge build-up:

For further ratings, dimensions and more, please refer the above Range tab, please see our catalogue or range tab above. You can also call/live chat with our expert team.

Got a quick question?

Use Live Chat. Or call us.

For instant advice use the Live Chat link to message one of the sales team. Or call them direct on +44 (0) 1384 881188

Not sure what flange spec you need?

Use the FlexEJ Flange Finder to find out

FlexEJ stock a full range of specs and types for our bellows. Or call our expert team on +44 (0) 1384 881188.


Who can you talk to?

Try our sales and customer service team on 01384 881188

They don't bite. And they know what they're talking about. Call the team any time from 8:30am to 3:30pm weekdays, 12:30pm Fridays or use LIVE CHAT if you would prefer a quick text answer. For more complex queries, send us any pro-forma documentation using the get a quote form below or email us

Call Us

Can't quite find the right bellow?

Try the FlexEJ Bellows Finder

Or call our expert team on +44 (0) 1384 881188

Frequently Asked Questions

Q. How do you identify flanges?
A. Our Flange Finder contains details for many common flanges. Typically, to be able to make the identification you need to know the bore size or outside diameter and number of bolts. For technical assistance contact us or use our Live Chat facility.
Q. Are FlexEJ’s Air and Dirt Separators available to purchase directly online?
A. Yes, the majority of FlexEJ’s current range of Air and Dirt Separators are available from the FlexEJ shop on a same-day despatch basis although our largest Air and Dirt Separators (DN100 to DN150) need to be pallet-delivered and require an extra 2-3 days for delivery. We can also supply Air and Dirt Separators on an ongoing OEM basis and can cater for custom requirements. Please ask for details.
Q. What is the delivery time for air & dirt separators?
A. Most of our air & dirt separators are available from stock on a 24hr delivery basis. Non-stock separators or custom-manufactured items typically take 7-14 working days, depending on options and quantities required.

Please visit our full FAQ page to see all our frequently asked questions.

Need a detailed quote?

Get A Quote. On us.

We will provide full technical details together with, pricing and shipping timescales. For more complex engineered quotes, preliminary sketches and calculations will be available.

Got a quick question?

Use Live Chat. Or call us.

For instant advice use the Live Chat link to message one of the sales team. Or call them direct on +44 (0) 1384 881188

Get A Quote

Please complete the short form here and we'll get back to you within 24hrs Monday to Friday (quicker if marked urgent).

Alternatively, you can also call our expert team directly on +44 (0) 1384 881 118 from 8:30AM to 4:30PM weekdays (12:30PM Fridays), who will be only too pleased to talk through your requirements and technical queries over the phone.

Visitors are also welcome Monday to Friday although please get in touch beforehand to let us know you're coming.

    Please treat this enquiry as: UrgentConfidentialProvisional

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    Industry experience

    FLEXEJ Ltd was formed in 2002 by two professional engineers who brought together an already highly respected design capability with business and commercial skills gained in large multinational companies.
    • Our focus has always been on application and design – helping our customers find the best value solution.
    • We have a strong engineering and manufacturing team with experience in petrochemicals, refining, nuclear, desalination though to HVAC.
    • The team is also very familiar with meeting complex requirements for documentation, in process NDT and test on projects. We have supplied many large end-users such as EDF, Exxon, Shell, Reliance & QatarGas working with major contractors such as JGC, Foster Wheeler & Technip.
    FlexEJ Industry Experience