CHIMNEY CAP UNIT FOR EXTINGUISHING A STARTING CHIMNEY FIRE

Abstract: Chimney cap unit for extinguishing a starting chimney fire, comprising a part which greatly restricts the draught during the fire in the flue, and a part which regulates the outflow of the remaining flue gas stream through the normal flue, in such a way that after a chimney fire the throughflow aperture is partially restored, so that no counterflow, which could result in flue gases entering the living-room, can occur in the flue.

Description: The invention relates to a chimney cap unit for extinguishing a starting chimney fire provided with a valve unit which under normal conditions are kept in an open position by means of a fuse or the like exposed to the flue gases and which in case of a chimney fire move automatically to a more or less closed position. Such a unit is known from FR-A-544465. After starting a chimney fire the valve unit is closed. However, the valve member is provided with a number of fixed apertures, so that the chimney is not completely shut-off. A complete shut-off could result in flue gases entering the living room during and after the chimney fire. The apertures in the known valve member have a fixed value. According to the present invention the unit is characterized in that the valve unit consists of two components, which form a single closed unit before the chimney fire occurs and which thereafter are separated, so that one component releases a predetermined aperture of the flue for the passage of the desired quantity of flue gas for the first phase of tempering the seat of the fire, while the other component subsequently releases an aperture which varies in size for smothring the seat of the fire and maintaining a slight upward flow of flue gases. In this way one component of the valve unit greatly restricts the draught during the fire in the flue and the other component regulates the outflow of the remaining flue gas stream through the normal flue, in such a way that after a chimney fire the throughflow aperture is partially restored, so that no counterflow which could result in flue gases entering the living room, can occur in the flue. Preferably the varying aperture is an aperture adjusting in dependence of the temperature of the flue gases. It is remarked that from US-A-4646847 a chimney cap unit is known whereby in case of a chimney fire the passage for the flue gases is completely blocked. Owing to the asymetric shape of the pivotable plate-shaped valve member the valve member will open again if owing to the high flue gas temperature below the plate the pressure will increase. Owing to the restricted opening of the valve member the pressure below the plate will decrease and the plate will close again completely. This process will continue several times. If the chimney fire is extinguished by smothering the flue gas temperature below the plate will again decrease. Finally the plate will not further open by insufficient pressure below the plate. Thus, the end position is a completely closed valve member, so that discharge of flue gas is not possible and flue gas may enter the living room or the like. From FR-A-2260736 a chimney cap unit is known with two distinct valve units, working independently of each other in which one unit releases a predetermined aperture, the other valve unit functioning as a shut-off valve. The invention is further explained with reference to the drawings. Fig. 1 shows on the left side of the centre line of the flue the cross section of the unit in the normal starting position, the right part showing the situation after it has gone into action; Fig. 2 shows a cross section of the lower part of the unit in the centre of the flue; Fig. 3 shows a cross section of the valve 7 along the line II - III of figure 1. Fig. 4 shows a top view of the unit in the direction of the arrow A; Fig. 5 shows a modified embodiment of figure 1. The unit according to the invention comprises a cap 1 with a central guide rod 2 connected thereto. A pipe 3 can move around this guide rod 2, but in the rest position said pipe is held by a test head (fuse) 4 by means of a supporting disc 5, in that the test head being fixed in the central guide rod 2. An auxiliary valve 6 is fixed to pipe 3 near the top of said pipe. A valve 7, which is centred around pipe 3 by means of spokes 7a, rests on said auxiliary valve 6. In the normal state the valve 7 rests on the auxiliary valve 6. When the device goes into action a predetermined gap 8 arises between auxiliary valve 6 and valve 7. A cylindrical sleeve 9 is fixed on said valve 7. A temperature-dependent (for example, diaphragm-type) valve 10 is fitted on the top of sleeve 9. It can be controlled by, for example, a bimetal in such a way that below a specific temperature the passage is fully opened, and above that is closed. In the closed position a predetermined aperture 11 is maintained (Fig. 4). In the normal position, in which the test head 4 retains the whole unit, the cylindrical sleeve 9 is pressed at the top against the inside of cap 1 by means of pipe 3, auxiliary valve 6 and valve 7. The cap 1 and flange 13 are fixed on the ring 14 with a number of distance bolts 12. The ring 14 is connected to the mouth of the flue. When the nuts 15 are loosened the entire internal parts can be removed for checking or for periodic cleaning of the flue. The adjustment then remains completely intact. Number 16 symbolizes a spark arrester. The whole unit acording to figure 1, 2 and 3 works as follows. After overheating of the test head 4, which is situated in the flue gases, disc 5 will no longer be supported, and therewith pipe 3, with auxiliary valve 6 attached thereto, and valve 7 - to which sleeve 9 and the temperature-dependent valve 10 are connected - will also move downwards. The valve 7 in the end hits the top edge (seat of valve 7) of ring 14 with force. The auxiliary valve 6 continues over a distance 8, thus forming an aperture between auxiliary valve 6 and valve 7. The situation which has thus arisen is shown in the righthand part of Fig. 1. The above-mentioned aperture brings about a first arresting of the seat of the fire. Through this aperture, the flue gases are able to pass out through the apertures 10 and 11. Due to the still high temperature of the flue gases, the temperature-dependent valve 10 is heated and will close. The chimney draught is further reduced, because only aperture 11 is available. Due to the small aperture and the flue gas flow being thereby delayed, the oxygen (air) supply to the seat of the fire will also decrease, so that the fire is smothered. The temperature will now drop, as a result of which aperture 10 will go into operation again. This means that a positive draught will always be present in the flue, and no dangerous flue gases will be able to penetrate into the living-room. In figure 5 a modified embodiment is shown, whereby again the left part is a cross-section in the normal starting position and the right part is a cross-section showing the situation after it has gone into action. Here also a test head 4, a guide rod 2 and a pipe 3 are used. Further, the auxiliary valve, indicated with 6' is fixed to the pipe 3. The other valve is indicated with 7'. According to this embodiment the auxiliary valve 6' is moving downwards with respect to the valve 7', see the right side of figure 5. In this way it is prevented that a strongly pollluted flue shall be closed by said auxiliary valve 6'. Further it is prevented that when the auxiliary valve 6' is not opened, for instance at very short pollution, there could occur a complete closing of the flue. The valve 7' is fixed to a bushing 20 which is slidable along the pipe 3, whereby a pressure spring 21 is acting between the auxiliary valve 6' and an abutment 22 on the upper end of the pipe 3. Between the guide rod 2 and the pipe 3 a key shaped member 23 is present around which the pipe 3 normally can move. The bushing 20 is provided with an abutment ring 24. If the unit comes into operation and the valves 6' and 7' are not separated owing to strong pollution the abutment ring 24 will abut the key shaped member 23, so that valve 7' will remain at a sufficient distance from the channel mouth. After some time of super heating of valves 6' and 7'by the hot flue gases the separation will as yet occur. The flue gases are flowing through the unit according to the arrows B in figure 5. With 25 a flue gas defecting plate is indicated.

Claims: A chimney cap unit for extinguishing a starting chimney fire provided with a valve unit (6,7) which under normal conditions are kept in an open position by means of a fuse (4) or the like exposed to the flue gases and which in case of a chimney fire move automatically to a more or less closed position, characterized in that the valve unit (6,7) consists of two components, which form a single closed unit before the chimney fire occurs and which thereafter are separated, so that one component releases a predetermined aperture (11) of the flue for the passage of the desired quantity of flue gas for the first phase of tempering the seat of the fire, while the other component subsequently releases an aperture (10) which varies in size for smothering the seat of the fire and maintaining a slight upward flow of flue gases. A chimney cap according to claim 1, characterized in that the varying aperture (10) is an aperture adjusting in dependence of the temperature of the flue gases.

Inventors: KONING, WIEBE
Applicants: KONING, WIEBE
Application year: 1988
Main classification: A62C3
IPC codes: A62C3