A1 Flues

Vermiculite flue pipe insulation

Vermiculite is a naturally occurring mineral that is ideal for use as flue pipe insulation. It is usually hand-filled into twin-wall flue systems and in-filled around equipment, within voids and in restricted areas.

It has the unusual property of expanding into worm-like, accordion-shaped pieces when heated. The expanded vermiculite is a lightweight, fire-resistant, absorbent and odourless material and is therefore ideal for use as flue pipe insulation.

On being suddenly subjected to high temperatures (700°C to 1000°C), vermiculite flakes will expand to many times their original size due to the microscopic layers of water turning to steam and forcing the laminar layers apart.

The properties of vermiculite flue pipe insulation include:

  • Sintering temp: 1,260°C %SiO2 46.0
  • Melting point: 1,330°C %TiO2 1.0
  • Specific gravity: 2.5 %Al2O3 9.8
  • Thermal conductivity (k-value): 0.063 W/mK %MgO 27.5
  • Specific heat: 1.8 kJ/kg.K %CaO 2.5
  • Cation-exchange capacity: 60 milli-equiv / 100g %K2O 2.8
  • Sintering temperature: 1,260°C

For technical help on vermiculite flue pipe insulation, either email our Technical Department at technical@a1flues.co.uk or call 01623 867303.