Not all polyurethanes are the same! NORRES uses a special polyurethanes mixture that is differentiated with the name Pre-PUR for several of its conduits. Our Pre-PUR raw materials are distinguished in the following ways from many of the membrane materials commercially available.

Applications of Membrane tube Diffusers

Membrane Tube Diffusers quality products from the NORRES stable – are mainly used for intermittent, fine-bubble, compressed air aeration (nitrification/deni-trification.) Our membrane material exhibits very good resistance to municipal wastewater according to the latest version of the DAW-M 115 Advisory Leaflet. Please ask NORRES for advice before using it in industrial wastewater.

  • Fine-bubble, compressed air aeration
  • Oxygenation and circulation in submerged fixed-bed and membrane bioreactors
  • Mixing of aeration tanks (municipal and industrial)
  • Grit trap aeration
  • Aeration of collecting and intermediate storage tanks
  • Restoration (aeration) of rivers and lakes
  • Aquaculture (fish farming)

Added value generated Membrane Tube Diffusers

  • 25% reduction in energy costs compared to conversational diffusers
  • ROI in approx. 6 months in contrast to conventional diffusers
  • High oxygen transfer efficiency (OTE) up to 5.5 kg/kWh with underdamped population density
  • Excellent value for money
  • Extremely durable-long service life
  • Quickly and easily fitted
  • Permanently elastic membrane
  • Excellent mechanical and chemical properties compared to silicone and EPDM
  • Optimised slit perforation

High potential saving compared to other, similar aeration systems

NORRES Membrane Tube Diffusers tear propagation strength and resistance to permanent kinking

The low resistance to permanent kinking and insufficient tear propagation strength of many conventional diffusers can lead to premature cracking under dynamic loads. The performance of the aeration system is significantly as a result.

Pre-PUR membrane tube diffusers are characterised by a very high tear propagation strength and far superior resistance to permanent kinking. The operational reliability and hence the performance of the aeration system are greatly enhanced.

Oxygen supply capacity/yield refer to full floor aeration with an arrangement density of 13% and a below-in depth of 3.84m. Measured in clean water according to DWA-M 209.

The efficiency and reliability of NORRES membrane tube diffusers can be increased by optimising and adapting the operating parameters. The permanent elasticity of the membrane has a crucial influence on the uniformity of the opening characteristic of the slit perforation over the full operating range. This in turn ensures a largely constant performance of the fine-bubble, compressed air aeration system.

Simply Flexible – our company motto unites the core message conveyed by our products with a corporate philosophy that is reaffirmed this flexibility as a vital precondition of our staying power and enduring market success. As a global player and one of the leading manufactures of industrial houses and hose systems in the world today, NORRES has always endeavoured to maintain its distinct identity.


  • Reliable, expert advice, either by phone or out in the field.
  • Comprehensive range of products available direct from stock
  • Marketing support


  • 25,000 m2 of warehouse space
  • 1 million metres of hose
  • 1 million component parts
  • 24-hour delivery service

Quality Management

  • High-quality products
  • Certification to DIN EN ISO 9001:2000
  • Our products comply with a wide range of standards and specifications in the most diverse industries

Research & Development Department

  • Technological innovations
  • Customized system solutions
  • Numerous novel and patented ideas have been realised in the last few years
  • Own R&D and Engineering departments