Heat Resistance


In the early 60's we started with the first heat tests. Now we conducts heat tests for all kind of fans and accessories:


  • Axial fans,
  • centrifugal fans,
  • jet fans and
  • dampers.


For these tests we uses their own heat test chambers, suitable for


  • impeller diameter up to 2240 mm,
  • temperatures up to 700°C and
  • power consumption up to 250 kW


as well as heat test chambers of independent organisations.

Heat tests approved by independent organisations

in addition to all the internal and unoffical heat testing that has been done for development purposes or according to customer wishes, many heat tests have also been made under the supervision of several independent organisations such as the MPA Braunschweig, the GERMANISCHER LLOYD, TüV, DNV etc.


Please find enclosed some official heat tests of our axial fans (dia 400 up to 2000 mm) as a sample:


  • Test 8557-2519, 250°C, 60min, TÜV Nord e.V.
  • Test WT1284/99, 250°C, 120min, Germanischer Lloyd
  • Test WT 834/98, 250°C, 180min, Germanischer Lloyd
  • Test WT 814/98, 250°C, 120min, Germanischer Lloyd
  • Test 95134-001-3H, 250°C, 60/120min, Germanischer Lloyd
  • ...


  • Test WT 880/98, 300°C, 30min, Germanischer Lloyd
  • Test 10927-040-3, 300°C, 150min, Germanischer Lloyd
  • Test 50-93-Wi-A01, 300°C, 120min, TÜV Nord e.V.
  • Test 10927-020-3, 300°C, 120min, Germanischer Lloyd
  • Test WT 835/98, 300°C, 60min, Germanischer Lloyd
  • ...


  • Test 10462-011-03, 400°C, 60min, TÜV Nord e.V.
  • Test CPN 97-1327, 400°C, 90min, Det Norske Veritas
  • Test 95102-001-3a, 400°C, 150min, Germanischer Lloyd
  • Test WT 1196/99, 400°C, 60min, Germanischer Lloyd
  • Test WT 1208/99, 400°C, 145min, Germanischer Lloyd
  • ...

Heat tests according EN 12101-3

The use of smoke and heat exhaust ventilation systems is to create smoke free areas before a buoyant smoke layer has become widespread.


Their value in assisting in the evacuation of people from construction works, reducing fire damage and financial loss by preventing smoke build-up, facilitating fire fighting, reducing roof temperatures and retarding the lateral spread of fire is firmly established.


For these benefits to be realised it is essential that smoke and heat exhaust fans operate fully and reliably whenever called upon to do so during their installed life. A heat and smoke exhaust ventilation system is a scheme of safety equipment intended to perform a positive role in a fire emergency.


This is why we have tested the entire axial fan range at the MPA Braunschweig and the independent institute CTICM (Centre Technique Industriel de la Construction Métallique) in Metz/France in accordance with the new EN 12101-3.


Axial fans have been tested already in the following classes:


  • Class F200 (200°C, 120 minutes) - passed
  • Class F300 (300°C, 60 minutes) - passed
  • 300°C, 120 minutes (special class) - passed
  • Class F400 (400°C, 120 minutes) - passed
  • 500°C, 90 minutes plus 700°C, 90 minutes (special class) - passed


All types were tested and certified individually in the required size range. Almost all common motor suppliers were also certified.


Witt & Sohn known as one of the leading fire damper manufacturers, has developed fire dampers for many different applications. These fire dampers have been certified by many classification societies as:


  • Maritime Equipment Directive (MED)
  • Det Norske Veritas (DNV)
  • Lloyds Register of Shipping (LRS)
  • Germanischer Lloyd (GL)
  • and anothers.


The dampers have been approved in different designs for the classes:

  • A-0,
  • A-15,
  • A-30 and
  • A-60.