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6.11 Requirements for plastic in the combustion product evacuation ducts, terminals and fitting pieces for boilers
6.11.1. Performance requirements 6.11.2 Thermal resistance
if the thermal resistance is not declared to be zero, the thermal resistance value of the chimney section declared by the manufacturer shall be verified by testing in accordance with 7.11 (
'6.11.3 Materials 6.11.3.1 Characterization
The material shall be identified by the thermal, mechanical and physicochemical behaviour.
The characterization shall include the density and at least 5 more properties. At least one property has to be taken of each of the three groups of methods in Annex A of EN 14471:2005.
The characterization methods shall be chosen in such a way that the characterization includes the relevant properties of the material. Examples are given in Annex B of EN 14471:2005.
6.11.3.2 Long-term resistance to thermal load
The material shall be capable of withstanding exposure to the nominal working temperature as described in 7.11.2.2.
The tensile modulus and the yield stress shall be measured in all cases.
In case of thermosetting plastics the flexural modulus and flexural strength shall also be determined.
In case of flexible tubes the ring stiffness shall also be determined.
Other relevant properties like the density or the impact strength shall be measured additional before and after the period of exposure, if they are relevant to evaluate the deterioration of the material.
The properties shall be determined in accordance with the methods of Annex R.
Alterations to the properties shall not exceed those set out in Table A4-2.
Table A4-2 — Criteria for testing long-term resistance to thermal load
If these values are not met, it is allowed to take new reference values obtained after 24 h exposure in air at nominal working temperature (conditioning) to release processing pressures/effects.
These effects are covered by the requirements for the mechanical stability of chimneys in accordance with 6.10.
6.11.3.3 Long-term resistance to condensate exposure
The combustion products evacuation duct with the terminal and fitting pieces shall be designed so that no
condensate remains.The material shall be capable of withstanding exposure to condensate as described in 7.11.2.3.
The tensile modulus and the yield stress shall be measured in all cases.
In case of thermosetting plastics the flexural modulus and flexural strength shall also be determined.
In case of flexible tubes the ring stiffness shall also be determined.
Other properties like the density or the impact strength shall be measured before and after the period of exposure if they are relevant, by evaluation of the deterioration of the material.
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Property Maximum permitted variation Impact strength ≤ 50 %
Tensile modulus ≤ 50 % Yield stress ≤ 50 %
Density ≤ 2 %
Flexural modulus ≤ 50 % Flexural strength ≤ 50 % Ring stiffness ≤ 50 %
Table A4-3 — Criteria for testing long-term resistance to condensate exposure
If the air supply and combustion products evacuation duct has been tested before on an appliance with a higher nominal temperature and/or thermal load this system will be deemed to meet these requirements.
6.11.3.4 Resistance to condensing/non- condensing cycling
After exposure in accordance with 7.11.2.4 the flue duct is disassembled and visually examined. It shall not show damages like cracks and pinholes.
The dimensions of the sections and fittings shall not change more than 2 %.
The tensile modulus and the yield stress shall be measured in all cases.
In case of thermosetting plastics the flexural modulus and flexural strength shall also be determined.
In case of flexible tubes the ring stiffness shall also be determined.
Other properties like the density or the impact strength shall also be measured before and after the period of exposure, if they are relevant to the evaluation of the deterioration of the material.
The properties shall be determined in accordance with the methods as given in Annex R.
The properties shall be determined in accordance with the methods of Annex R.
Alterations to the properties shall not exceed those set out in Table A4-3.
( Table A4-4 — Criteria for testing resistance to condensing/ non- condensing cycling Alterations to the properties shall not exceed those set out in Table A4-4.
If the values are not met, it is allowed to take new reference values obtained after 24 h exposure in air at nominal working temperature (conditioning) to release processing pressures/effects.
NOTE If these values are not met, it is allowed to take new reference values obtained after 24 h exposure in air at nominal working temperature (conditioning) to release processing pressures/effects.
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Property Value
Impact strength ≤ 50 % Tensile modulus ≤ 50 % Yield stress ≤ 50 %
Density ≤ 2 %
Flexural modulus ≤ 50 % Flexural strength ≤ 50 % Ring stiffness ≤ 50 %
Property Value
Impact strength ≤ 30 % Tensile modulus ≤ 30 % Yield stress ≤ 30 %
Density ≤ 2 %
Flexural modulus ≤ 30 % Flexural strength ≤ 30 % Ring stiffness ≤ 30 %
These effects are covered by the requirements for the mechanical stability of chimneys in accordance with 6.10.
Those parts of the air supply and combustion products evacuation duct that are exposed to UV shall be tested in accordance with 7.11.2.5.
After the exposure test the following requirements shall be met:
– the impact strength, as given in Annex R, shall not change more than 50 %.
– in case of thermosetting plastics the flexural modulus and flexural strength, as given in Annex R, shall not change more than 50 %.
The above tests shall be carried out in such a way that the maximum stress will occur at the radiated side of the test pieces.
Testing is not necessary in cases where the free end of the plastic flue duct (terminal) is not more than 2D but maximum 0,4 m in length exposed to UV of the sun.
6.11.3.6 Geometrical stability
After exposure in accordance with 7.11.2.6 the change in internal diameter/length of the pipe shall not exceed 2 %.
For each size group of diameters one size shall be tested.
6.11.3.7 Reaction to fire
The reaction to fire shall be declared by the manufacturer according to EN 13501-1, but shall be equal or better than E.