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B&ES release DW/144

The ductwork industry is bracing for a new era with the publication of a radical new version of its primary specification document.

The revised DW/144: Specification for Sheet Metal Ductwork produced by the Building & Engineering Services Association (B&ES) has been hailed as the “most radical document to hit the industry in 30 years” by former president Gareth Vaughan.

This comprehensive reference work – recognised as the standard specification for the manufacture and installation of low, medium and high pressure/velocity sheet metal air systems – has had a thorough revamp and upgrade to make it more in tune with today’s modern, digital industry.

The first ductwork specification was published by B&ES just over 50 years ago, so it is pleasing to be able to mark the anniversary with such a fresh and modern revision of the sector’s seminal design document.

Immediate past president Bruce Bisset also welcomed the first revision of the document for 16 years, describing it as “one of the most distinguished, authoritative and widely used of all the standards and good practice guides published by the B&ES”.

The revised DW/144 includes provision for reducing the thickness of the sheet metal used in some sizes of rectangular ductwork. This will have a major effect, not just from an environmental and resource-efficiency perspective, but also on the competitiveness of the product.

For years, ductwork specialists have argued that some gauges were over-specified and, therefore, thicker than they needed to be for many applications.

The revised DW/144 addresses this and supports the case for thinner gauges with in-depth test data and validation. The revised document also includes new approaches to the fire rating of ductwork, looks at new techniques for supporting ductwork and outlines changes to galvanising and spot welding procedures.

The savings from using reduced steel gauges in some types of ductwork could be passed on to end users and would cut the cost of manufacturing and transportation for the industry. It also brings the industry’s specification into the digital age by better reflecting modern working practices and aligning it with the emergence of building information modelling (BIM).

The 200-page document, which has been aligned to all current British, European and international standards, covers ductwork application, materials, classification and air leakage rates.

It defines the technical information to be provided by system designers to ductwork contractors and looks in detail at rectangular, circular, and flat-oval ductwork.

The content has been expanded to give more detail on hangers and supports, smoke and fire dampers, external ductwork, internal duct linings, thermal insulation, air terminal units and connections to builders’ work, as well as reaffirming the importance of the provision of a clean, dry environment into which sheet metal ductwork should be installed. It also contains a large number of reference tables.

Special emphasis has been placed on the inclusion of access panels in ductwork installations to make it easier for systems to be properly cleaned and maintained in situ.

Often access panels are left out to save up-front costs at the long-term expense of the end client.

Peter Rogers is chairman of the B&ES Ductwork Group technical committee

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