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caswell.pngFamily-owned and independently-operated FIRESAFE FIRE RATED DUCTWORK® Ltd are a British engineering company with wide experience and unparalleled expertise in the Passive Fire Protection industry. It designs - and holds the Intellectual Property rights for CASWELL FIRESAFE® non-coated fire-resisting ductwork systems.

The non-coated system achieves its high rating for fire resistance from its superior design specification and construction. Manufacture and installation is strictly prescribed and controlled.

Manufacturing and certification rights for CASWELL FIRESAFE® products are licensed to a select group of International Partners in the UK, EU, the Middle East & Asia.

CASWELL FIRESAFE® systems have been successfully installed on many prestigious commercial projects around the World including UK, Eire, Hong Kong, Macau, UAE, Oman and Qatar.

C. Caswell Engineering Services Limited are proud to be a FIRESAFE FIRE RATED DUCTWORK® licensee for the UK.


firesafe-logo.pngCASWELL FIRESAFE® systems are classed as Passive Fire Protection and protect against the spread of fire from one compartment to another. It provides this assurance without the need for fire dampers, enclosures, spray or fabric coverings.

CASWELL FIRESAFE® products are also used for smoke control; in which case passive fire systems must operate under fire conditions. It can be used to quickly and safely exhaust smoke and, as an integral part of a pressurised system, prevent it from entering protected fire escape routes to maximise valuable escape time.

The CASWELL FIRESAFE® system was first developed and tested in the early 2000’s in accordance with British Standard BS476 : Part 24 (1987) at Warrington Fire Research (now Exova Warringtonfire). The products we provide have been tested to BS 476 : 24 (1987), for up to 4 hours stability and integrity and up to 4 hours insulation. Since then, the introduction of harmonised European Standards has involved extensive investment and further testing in order to meet UK and European legislation, including CE marking. The products have been tested to EN1366-1 (2014) and EN1366-8 (2004) various classifications achieved up to 2 hours.

CASWELL FIRESAFE®   Key specification parameters

  • Rectangular duct up to 3000 mm x 3000 mm
  • Circular duct up to 1250mm diameter
  • Special panel construction ducts up to 8m longest side
  • Horizontal and vertical orientations
  • Available in Mild steel, Galvanised Steel & Stainless Steel
  • Conventional or Fully Welded ‘Grease Tight’ construction
  • Test evaluation for ‘Fire Outside’ & ‘Fire Inside’ scenarios
  • High-temperature balancing dampers
  • Fire rated Access Doors (Insulated and Uninsulated)
  • Fire rated Silencers
  • Bespoke design for ductwork support systems
  • Insulation systems from 30 min up to 240 min ratings

Ducts which penetrate the compartment walls and floors must achieve the same fire resistance as the compartments through which they pass.

Product Data Sheets detail the range of capabilities for which CASWELL FIRESAFE® is certified. Classifications apply equally to horizontal and vertical (riser) ductwork and relates to both Fire Outside Duct (Type A) and Fire Inside Duct (Type B) fire performance testing.

Click Caswell Firesafe Product Data Sheet BS Version 2.0 to go to the FIRESAFE PDF link page.

CASWELL FIRESAFE®   The non-coated advantage   

Non-coated ductwork has many performance benefits but it also holds significant commercial and environmental advantages over other systems which employ flame retardant coatings, coverings and / or particulate board cladding systems. These additional treatments involve extra cost and risk throughout the supply chain as:

  • Additional, potentially hazardous, chemicals need to be purchased, stored and used to degrease, etch, prime and apply a coating
  • Additional energy is expended to cure a coated finish
  • Processing time is extended as a coating must fully cure before the product can be used; occupying valuable manufacturing / indoor storage space in the meantime
  • Any damage to a coating during manufacture will add delay - and disrupt the factory schedule - whilst it is reworked and re-inspected before shipping
  • Any damage to a coating during transportation would necessitate its return or replacement, adding unscheduled time, cost and logistical effort
  • Any damage to a coating, covering or cladding treatment during installation or any subsequent time could, if not identified and addressed, compromise the fire resisting integrity of the building and, ultimately, the life-safety of its occupants

Non-coated product completely negates all the above issues.
The product can be fabricated swiftly and without difficulty, leading to significant time & cost savings in the manufacturing process. Non-coated product assures that ‘just in time’ or short lead contracts can be fulfilled and that both installation contractors and the Main Contractor can be confident that Plan of Work deadlines will be met, so avoiding potential penalties.


The team at FIRESAFE FIRE RATED DUCTWORK® Ltd provide technical support and project related assistance to all licensed Partners including:

  • Provision of bespoke ductwork support systems
  • Technical assistance with non-standard installations / manufacturing details
  • Regular auditing of Partners to ensure compliance with specifications and procedures
  • Local authority approvals assistance 

CONTRACTORS   Your Responsibility. Our Assurance

If it is your responsibility to manage passive fire protection products, materials or systems - directly or indirectly - then the onus is on you to ensure that they are ‘fit for purpose’.
You must ensure that the manufacturer’s fire test and certification evidence fully covers the intended use. It is also your responsibility to ensure that the installer can demonstrate appropriate competency in the installation of the passive fire protection products, materials and systems used.

It is essential that the system is considered ‘as a whole’, including ductwork, fittings, supports, access doors, attenuators, gaskets, sealants, flange clamps and fixings.      

Caswell Engineering will be with you every step of the way to make sure that your system is compliant and that you fully meet your legal responsibilities. On completion of an installation of CASWELL FIRESAFE® product, our Engineers will arrange to visit the project site to inspect the installation and, once verified that it meets all requirements, will issue a Certificate of Conformity.

Contact us now to obtain a quotation based on your bespoke specification requirements


FIRESAFE FIRE RATED DUCTWORK® Ltd work with several highly respected, globally recognised accredited testing facilities and certification bodies as part of the on-going development of the CASWELL FIRESAFE® range of fire resisting ductwork.

The CASWELL FIRESAFE® non-coated fire resisting ductwork system manufactured by C. Caswell Engineering Services Limited has undergone extensive testing to both British and European standards. Tests to BS 476 Part 24 : 1987 [Method for determination of the fire resistance of ventilation ducts] were principally conducted at the laboratories of NAMAS / UKAS accredited Exova Warringtonfire (formerly Warrington Fire Research). EN 1366-1 & EN 1366-8 tests were performed at Applus+ laboratories in Barcelona.

Our systems have also been assessed and certified by the following organisations / schemes. Relevant test criteria, along with assessment and certification data for each organisation, is available on request.


Logo and trademarks are reproduced here with the kind permission of the respective body. All rights acknowledged.

These organisations are internationally recognised 3rd party experts in the field of Passive Fire Protection and our systems can be found listed in their web-based certification files.         
To maintain these online listings, Partners of FIRESAFE FIRE RATED DUCTWORK® Ltd, and their respective manufacturing facilities, are audited. This involves stringent checks that the materials produced, the quality regime, traceability, corrective actions and certification are all in accordance with the prescribed specifications and procedures.

An ongoing programme of periodic physical inspections is also conducted by FIRESAFE FIRE RATED DUCTWORK® Ltd on all Partners and their respective facilities to ensure the required standards are maintained.

CASWELL FIRESAFE® non-coated fire resisting ductwork system manufactured by C. Caswell Engineering Services Limited is certified by the LPCB (Loss Prevention Certification Board). This certification gives the end-user client the added reassurance of a fire-rated system that is recognised by Insurance companies. View the CASWELL FIRESAFE® listing on Red Book Live

CASWELL FIRESAFE® is manufactured within an ISO9001 accredited, purpose built factory which is regularly audited by LPCB in accordance with the requirements of LPCB : FPC (Factory Production Controls).

The above controls ensure that CASWELL FIRESAFE® product is manufactured, installed and certified to the highest standards. This serves to provide peace of mind to any person or organisation responsible for specifying, approving and / or providing compliant fire-resisting systems.  

FIRESAFE FIRE RATED DUCTWORK® Ltd are full members of the ASFP (Association for Specialist Fire Protection) and have representatives on the Ductwork & Dampers Technical Group (TG6). Technical staff also sit on the Technical Committee for Fire Resisting Ductwork at the BSI (British Standards Institute). 

Explaining ‘Stability, Integrity & Insulation’ according to BS476-24

Stability - The ability of ductwork - and crucially inclusive of its support system - to remain intact and fulfil its intended function for a specified period of time

Integrity - The ability of ductwork to remain free from cracks, holes or openings outside the compartment in which the fire is present for a specified period of time

Insulation - The ability of ductwork to maintain its separate function without developing temperatures on its external surface, outside the compartment in which the fire is present, which exceed 140°C (284°F) as an average above ambient and / or 180°C (356°F) as a maximum above ambient at any one point.

For Kitchen Extract ductwork (Duct A) these limitations also apply to the internal surface of the duct within the compartment in which the fire is present. All systems are manufactured to satisfy the requirements of recognised ductwork specifications including DW 144 and DW 172


Continuous Product Development

In addition to their technical support, FIRESAFE FIRE RATED DUCTWORK® Ltd are continually developing the CASWELL FIRESAFE® system. They are actively undertaking EN Standards testing, which will result in CE marked product to comply with the latest legislation for the UK and Europe.


As well as continuing to provide full support to its existing Partners, FIRESAFE FIRE RATED DUCTWORK® Ltd is always keen to speak with potential new Partners and evaluate unrepresented territories where there are demands for high quality British-designed & developed products. This process includes exploration and full understanding of local markets, standards, codes and associated legislation relating to Passive Fire Protection and fire resisting ductwork systems.

For a more detailed look at the CASWELL FIRESAFE® ductwork product please click FIRESAFE FIRE RATED DUCTWORK® to go to the official website.