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TBMA S-AX dust valves are specially designed to be used under dust filters and cyclones. Applications with a differential pressure up to 500 mbar where the valve primarily functions as an airlock or explosion barrier. The S-AX can be used as a protective system up to 2,5 barg for products in dust class St1 and St2. (optional)

These airlocks are made from GN40 nodular cast iron. This type of cast iron material is stronger and much less brittle than conventional cast iron, making it more resistant to shock loads, and has a high corrosion resistance. The installation weight of the S-AX is only 65 kg. The result is a particularly favourable price/quality ratio of this type of valves.

The S-AX valves are equipped with a round and a square connecting flange. This allows the valve to be used as a transition piece from round to square and vice versa.

Are you looking for a rotary valve? Use our Rotary Valve Specification Form as a guide to ask for a quotation and send it to We will contact you asap.


TBMA industry applications  S-AX dust lock

In brief

  • Light and compact dust valve
  • For differential pressure up to 500 mbarg and easy to process products
  • Body and covers made from high-tech GN40 nodular cast iron
  • Outboard bearing, dust-tight and sealed for life
  • Protective system up to 2,5 barg for products in dust class St1 and St2 (optional)
  • ATEX 2014/34/EU certified (optional)


  • Flange size: DN250 (round/square)
  • Flanges: drilled in accordance with PN10
  • Rotor volume: 9,5 ltr/rev
  • Differential Pressure: 0,5 barg
  • Standard design temperature: 70 °C


S-AX 250X

  • Rotor with 8 polyurethane blades
  • ATEX 2014/34/EU certified (optional)
  • Direct drive with Helical-worm geared Nord or Euronorm motor reductor

S-AX 250X-1 | Specifications as S-AX 250X extended with:

  • Protective system up to 2,5 barg for products in dust class St1 and St2

More info

Brochure Rotary Valves View

Dimensions S-AX View

Air leakage diagram S-AX View

Rotary Valve Specification Form View


Curious when to use the above system? Have a look at our selection of industries for a suitable application of this system and of our other products.

Looking for a more specific industry and/or application? We are happy to take on the challenge! Contact us at



TBMA are specialists in the design and supply of components and systems for bulk solids handling. Our extensive range of high quality processing equipment is suitable for handling powders and granules with proven reliability in practice in a variety of processing industries. The highly qualified and experienced TBMA staff are well able to translate your requirements into the right execution and application of our components. We also offer the design and execution of complete projects, thus providing you with an efficient, reliable and sustainable solution for your process.

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