FOCOLARI in ghisa
6097000 – EN
19
4.2.
BEAM PROTECTIONS
Considering the irradiation of the hearth, it is necessary to be particularly careful in protecting the beams while
designing your stack. Consider the proximity of beams to the external surfaces of the hearth, on one side, and the
irradiation of the glass door, usually very close to the beams, on the other side. In any case, it has to be considered
that the internal or lower surfaces of this beam in flammable material must not come in contact with temperatures
higher than 65 °C. Picture 4 gives some examples of execution.
WARNING: We cannot be made liable for a wrong operation of the plant, when it does not comply with the
provisions of these instructions or when it uses additional products not suitable for this device.
5.
FLUE
Essential requirements for a correct operation of the device:
•
the internal section must be preferably circular;
•
be thermally insulated and water-proof and produced with materials suitable to resist to heat,
combustion products and possible condensates;
•
not be throttled and show a vertical arrangement with deviations not greater than 45°;
•
if already used, it must be clean;
•
observe the technical data of the instructions manual;
Should the flues have a square or rectangular section, internal edges must be rounded with a radius not lower than 20
mm. For the rectangular section, the maximum ratio between the sides must be = 1.5.
A too small section causes a decrease of the draught.
It is suggested a minimum height of 4 m.
The following features are forbidden and therefore they endanger the good operation of the device: asbestos cement,
galvanized steel, rough and porous internal surfaces. Picture 5 gives some examples of execution.
The minimum section must be 4 dm
2
(for example 20 x 20 cm) for devices whose duct diameter is lower than
200 mm or 6.25 dm
2
(for example 25 x 25 cm) for devices with diameter greater than 200 mm.
The draught created by the flue must be sufficient, but not excessive.
A too big flue section can feature a too big volume to be heated and consequently cause difficulties in the operation of
the device; to avoid this, tube the flue along its whole height. A too small section causes a decrease of the draught.
The flue must be properly spaced from any flammable materials or fuels through a proper insulation or an air
cavity.
It is forbidden to let plant piping or air feeding channels pass in the same flue. Moreover, it is forbidden to create
movable or fixed openings on the same for the connection of further other devices.
Picture 4
Picture 5
(1) Beam;
(2) Refractory insulating;
(3) Air pocket;
(4) Metallic protection.
(1)
(1)
(4)
(2)
(2)
(3) 10 mm
(3) 10 mm
(1)
(3) 10 mm
(2)
(1)
(2)
(3) 10÷50 mm
(1)
(3) 10 mm
(2)
(4)
(1)
(3) 10 mm
(2)
1) AISI 316 steel flue with double chamber insulated with material resistant to 400°C.
Efficiency 100% excellent.
2) Refractory flue with double insulated chamber and external coating in lightweight
concrete. Efficiency 100% excellent.
3) Traditional clay flue square section with cavities. Efficiency 80% excellent.
4) Avoid flues with rectangular internal section whose ratio differs from the drawing.
Efficiency 40% poor.
A+1/2A
A
Max.
A+1/2A
(3)
(1)
(2)
(4)
