BS EN 777-1:2009 pdf download – Multi-burner gas-fired overhead radiant tube heater systems for non- domestic use Part 1: System D — Safety
ln particular，when the system is installed according to the manufacturers instructions，all thecomponents shall withstand the mechanical，chemical and thermal conditions to which they may besubjected when used in a manner which can be reasonably foreseen.
Copper shall not be used for gas carrying parts where the temperature is likely to exceed 100 °c.
Asbestos or materials containing asbestos shall not be used.
Solder that has a melting point below 450 °C after application shall not be used for gas-carrying parts.
5.1.3Accessibility for maintenance and use
Components and controls shall be arranged such that any adjustment, maintenance or exchange is easywithout removing the radiant tube from the installed position. Where necessary，access doors orremovable panels shall be provided.
Parts that are intended to be removable for maintenance or cleaning shall be readily accessible, shall besimple to assemble correctly and difficult to assemble incorrectly.Such parts shall be difficult to assembleincorrectly where incorrect assembly would create a hazardous condition or result in damage to thesystem and its controls.
Parts of the system which are not intended to be removed by the user and for which removal would affectsafety shall be capable of removal only with the aid of tools.
5.1.4 Means of sealing
5.1.4.1 Soundness of the gas circuit
Holes for screws, studs, etc. intended for the assembly of components shall not open into the gasways.The wall thickness between holes (including threads) and gasways shall be not less than 1 mm.
The soundness of components and assemblies connected to the gas circuit and likely to be dismantledfor routine maintenance at the consumer’s premises shall be assured by means of mechanical joints,(e.g. metal to metal joints,O-ring joints or packing) but excluding the use of any sealing compound suchas tape, mastic or paste.The soundness shall be maintained after dismantling and re-assembly.
Sealing compounds may be used for permanent threaded assemblies. The sealing material shall remaineffective under normal conditions of system use.
5.1.4.2Soundness of the combustion circuit
The soundness of the combustion circuit of the system shall be effected by mechanical means only, withthe exception of those parts which do not require to be disconnected for routine maintenance, and whichmay be joined with mastic or paste in such a way that permanent soundness is assured under normalconditions of use (see 8.2.2.1 c).
5.1.5 Supply of combustion air and evacuation of combustion products
5.1.5.1 Air inlets
All openings for the supply of air into the system shall be adequately protected against inadvertentblockage. Iin addition, such openings shall not permit the entry of a ball of 16 mm diameter applied with aforce of 5 N.The cross-section of the air passageway(s) shall not be adjustable.
5.1.5.2 Combustion circuit The cross section of the combustion circuit shall be adjustable by means of one or more dampers to permit individual sections of the system to be adjusted within prescribed limits of suction in the combustion circuit, as declared by the manufacturer for the correct operation of the system. Each damper shall be supplied by the manufacturer and once adjusted shall be capable of being locked and sealed in position. With the damper in its fully closed position, there shall be at least 2 % of the cross-sectional area of the tube open to permit the venting of any gas build up.
5.1.5.3 Flue outlet
The POCED shall either be supplied with the appliance by the manufacturer or specified in the manufacturer’s instructions. The specification shall include a description of the duct including any bends, its materials of construction and any critical tolerances (e.g. in length, diameter, thickness, insertion depth). The manufacturer shall state the minimum and maximum equivalent resistance.
The manufacturer’s instructions shall give details for calculating the equivalent resistance (e.g. the allowance to be made for bends). Where the appliance is intended to be fitted to a flue having a wall termination, the manufacturer shall either supply a flue terminal or state the type of termination which shall be used. The design of this shall be such that it will not allow entry of a ball of 16 mm diameter applied with a force of 5 N. If the POCED is capable of being installed in accordance with the manufacturer’s instructions such that its outlet, when fitted with any terminal supplied with the appliance, or specified in the manufacturer’s instructions, extends beyond the external surface of a building by more than 1,5 m, this duct shall not undergo any permanent distortion when subjected to the wind load test specified in 4.3.2 of EN 1859:2000.