BS 5991:2006 pdf download – Specification for indirect gas fired forced convection air heaters with rated heat inputs greater than 330 kW but not exceeding 2 MW for industrial and commercial space heating – Safety and performance requirements (excluding electrical requirements) (2nd family gases)
The appliance shall be at room temperature at the start of each test unless the test method specifies otherwise. Unless the test method specifically requires otherwise, the appliance shall be operated at the design temperature rise ± 10%.
During testing, the initial adjustment of the appliance shall not be altered unless specifically required by the test method. Precautions shall be taken to prevent thermostats or other variable controls from acting so as to interfere with the gas flow, except as necessitated by the test. Gas test pressures shall be accurate to within ± 0.2 mbar and so controlled that the variation does not exceed ± 0.2 mbar.
In general, except for tests involving governor performance, the appliance governor may be put out of action and the specified test pressureobtained by adjustment of the gas pressure at the inlet to the appliance.
The heat input to the appliance shall be determined as specified in 6.3.2 of BS EN 621:1998 or 6.3.2 of BS EN 1020:1998 depending on whether the appliance incorporates a fan to assist transportation of combustion air and/or combustion products.
7 Design and construction
7.1 All appliances
7.1.1 Materials, fittings and finishes The appliance, including all its component parts, shall be soundly constructed and of a high standard of workmanship and finish. Materials shall be of a type, quality and thickness appropriate to the application. In particular, all parts of the equipment shall be resistant to mechanical stresses, including shock, vibrationally or chemically or thermally induced, to which they may be exposed during any conditions of operation.
Under normal conditions of use, maintenance and adjustment they shall show no changes that might adversely affect their function. Such materials, fittings and finishes shall conform to the requirements of the relevant British Standards and shall all be appropriate to the conditions arising in the part of the appliance in which they are used.
The appliance and its components shall be free from swarf, grit or other foreign matter. Materials containing asbestos shall not be used.
7.1.2 Flueways: natural draught burners For air heaters fitted with natural draught burners, the combustion chamber and flueways shall be so designed that there is no descending section that is capable of creating reverse flows.
7.1.3 Component location Parts that are intended to be removable for maintenance or cleaning shall be readily accessible, shall be easy to assemble correctly and impossible to assemble incorrectly where incorrect assembly would create a hazardous condition or result in damage to the appliance and its controls. The burner(s) shall be positively located and so arranged that misalignment cannot occur. It shall not be possible to loosen complete burner assemblies, jets or injectors without the use of tools.
7.1.4 Injectors and jets Injector and jet orifice areas shall be non-adjustable.
7.1.5 Gas rate adjusters Adjustable gas rate adjusters shall be readily distinguishable from other manual valves. The setting of adjusters shall be protected by a method that discourages unauthorized adjustment.
7.1.6 Materials in contact with gas Copper tubing shall not be used where it is likely to be exposed to temperatures above 100 °C. Solder that has a melting point below 450 °C after application shall not be used for gas-carrying parts.
7.1.7 Aeration adjustment (natural draught burners) Any means of adjusting the primary aeration ofnatural draft burners shall be preset and locked by the manufacturer.
7.1.8 Insulation Thermal or acoustic insulation shall be non-combustible in accordance with the requirements of BS 476-4, shall be securely located and shall be protected against mechanical damage, condensate and vermin. Gas-carrying parts in contact with, or passing through, insulating material shall be adequately protected against possible corrosive effects of the insulant.