Midflex 904L - Summary

Midflex 904L - Summary | Technical | All


Class 1 Flexible Chimney Liner.

Twin Wall Multifuel Flexible Liner in 904L grade stainless steel.

  • Available in sizes from 125 to 200  mm
  • Stocked in sizes from 125 to 200  mm
  • Maximum operating temperature 600 deg C
  • Standard finish is: 904 stainless finish
  • Supplied Fully bubble wrapped and labelled

  • 1 year manufacturer's warranty for all products installed and maintained in accordance with the installation and usage notes.

Midtherm Flue Systems Limited offer an extended 35 year warranty for Midflex 904L for registered systems installed and maintained in accordance with the guidelines in our extended warranty scheme.

Midflex 904L is suitable for use on the following applications:

Midflex 904L Description:

  • Midtherm Midflex 904L is a twin wall flexible liner made from 904L grade stainless steel (a high performance austenitic stainless steel) with high levels of chrome, nickel, molybdenum and copper which provide it with the exceptional corrosive resistance.

  • The Midflex 904L is extremely resistant to pitting and crevice corrosion and has very good resistance to stress corrosion cracking.

Midflex 904L Installation and Usage Notes

All flue system installations, i.e. oil, gas, solid and multi fuel, should be carried out by a suitably qualified installer or Building Control Department permission must be granted.


For detailed installation guidelines please refer to:

  • The relevant Technical Information and Installation Instructions
  • Building Regulations
  • Planning Office
  • Appliance Manufacturers Operating and Maintenance Instructions
  • Relevant British Standards




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