BS EN 16497-2-2017 pdf free download.Chimneys — Concrete System Chimneys Part 2: Balanced flue applications
4 Form
The concrete system chimney for balanced flue applications shall comprise of flue blocks, which may be of single wall or multi wall construction, and a combustion air supply duct.
In the context of this standard the term ‘flue block’ means a vertical element of a system chimney which may also comprise the following items where appropriate.
— Flue blocks according to EN 1858
— Flue liners according to EN 1857
— Insulation layer;
— outer wall elements according to EN 12446, or EN 13069, or of appropriate metal;
— mortar for jointing flue liners;
— mortar for jointing a flue block or outer wall elements;
— terminal;
— chimney base;
— cladding;
— opening section;
— reinforcement for handling.
— Pressure equalising opening
— Combustion air supply duct.
This duct may be an additional passage within a flue block, or a separate duct, possibly of other materials.
Single wall or multi-wall flue blocks shall be manufactured in one of the following forms:
— single flue;
— multi-flue;
— flue/combustion air/ventilation combination.
NOTE See Annex B for examples of typical flue block types.
Flue blocks shall have a maximum of four flues, combustion air or ventilation passages.
5 Materials
5.1 General
The wall or walls of concrete flue liners or concrete flue blocks shall be precast concrete. For multiwall concrete flue blocks the concrete liner and outer wall may be separated by an air space or insulation.
The material of a separate combustion air supply duct may be same as the flue liner or flue block or be of other materials, e.g. metal tube, but it shall have the appropriate resistance to fire external to external.
Materials used in the manufacture of system chimneys shall be identified for factory production control purposes.
When insulation forms part of a system chimney, it shall be of bonded material as specified by the manufacturer. If the insulation is supplied as a separate item, it shall be installed in accordance with the system chimney manufacturer’s installation instructions.
The manufacturer shall declare the density of any insulation and the bulk density of the concrete elements and when tested to A.11 the density shall be within ± 10 % of the declared value (see 8.10).
CE-marked chimney components are deemed to satisfy these requirements.
5.2 Reaction to fire
In accordance with Commission Decision 96/603/EC, as amended, concrete elements of system chimneys to this standard are classified as reaction to fire class A1 without test provided they contain not more than a mass or volume fraction of 1 % (whichever is the more onerous) of homogeneously distributed organic materials.
5.3 Reinforcement for handling
5.3.1 Where a concrete element is reinforced for handling, the reinforcement shall have a maximum diameter of 8 mm and a minimum concrete cover of 15 mm on all sides for temperature classes up to and including T250 and a minimum concrete cover of 20 mm on all sides for all other temperature classes.
5.3.2 In concrete elements having a bulk density of less than 2 000 kg/m 3 , when measured in accordance with A.10, any reinforcement shall be protected against corrosion by one of the following means:
a) use of stainless steel;
b) by completely covering any mild steel reinforcement with a coating (e.g. typically Portland cement CEM I or CEM II mixed with water to form a slurry, or epoxy resin).
CE-marked chimney components are deemed to satisfy these requirements.
6 Surface treatment
Any surface treatment of the concrete elements, e.g. render, shall be applied, as described by the product manufacturer, before the product is tested.
7 Tolerances on dimensions of individual concrete components
7.1 Declared dimensions
CE-marked chimney components according to EN 1857, EN 1858, EN 12446 and EN 16497-1 are deemed to satisfy these requirements.
Tolerances on manufacturer’s declared dimensions of concrete components, including taper, shall be:
a) Declared internal transverse dimensions
below 300 mm : ± 3 mm
300 mm and above : ± 1,5 %
b) Declared height
below 300 mm : ± 5 mm
300 mm to 700 mm : ± 7 mm
above 700 mm : ± 10 mm
c) Storey height elements constructed from individual blocks
Declared height up to 3 m ± 10 mm
Declared height over 3 m ± 30 mm
d) Declared overall wall thickness.BS EN 16497-2 pdf download.