The invention relates to a fire protection system for use with at least one line extending above a floor, said line containing a combustible liquid.

Such a fire protection system, for example in the shape of a protective sheath to be provided around the line, is generally known.

The line containing the combustible liquid, which extends above the floor is e.g. a power cable passed into transfor¬ mer stations of electricity companies. Said power cable, which is filled with pressurized oil functioning as an electric insulator, comprises a multi-conductor core. Said multi-conductor core is wrapped in several layers of paper, whilst said layers of paper in turn are encased in a lead sheath. Along its entire length the power cable contains about 70 litres of oil under an (excess) pressure of approximately 0.8 bar. In a transformer station several power cables, together occasionally called "fields", are connected to a central switch device. In case of a local fire in a transformer station there is a danger that one or more power cables catch fire. When the lead sheath is attacked by the fire, the pressurized oil present in the power cable will flow out. Said oil will also be ignited then, so that burning oil will spread across the entire floor. When subsequently a power cable of an adjacent field is reached, this cable will also be set afire, and thus the fire will spread. Since a transformer station comprises several fields, with each field containing about 70 litres of oil, a few hundred litres of oil can be set afire in case of a calamity. The heat caused by the burning oil may then lead to the combustion of other combustible materials present in the transformer station.

A drawback of the known fire protection system is that in case of a local fire near the line extending above the floor, with the combustible liquid present therein, provides insufficient protection against fire for the area around the line.

The object of the invention is to provide a fire protection system which, in case of a fire, offers an excellently protection against fire for the area around the line - i.e. in case of a fire in a transformer station, e.g. power cables located adjacent to the line.

In order to accomplish that objective a fire protection system of the kind mentioned in the preamble is charac¬ terized in that said fire protection system comprises a liquid collecting device to be provided on or at least partially in said floor, said liquid collecting device in its mounted condition extending along at least part of the length of said line.

One embodiment of a fire protection system according to the invention is characterized in that said liquid collecting device is provided with at least two reservoirs abutting against one another. By distributing the combustible liquid leaking from the line over said separate reservoirs upon being collected, a number of small fires will start in case of a fire.

Another embodiment of a fire protection system according to the invention is characterized in that said at least two reservoirs have different volumes, and that an overflow is present between said at least two reservoirs. As a result of this it can be achieved that the combustible liquid collected in the reservoirs can be carried off towards the outside - when seen from the position of the line - so

that the liquid can be kept away from the line as far as possible. It is noted that the different volumes of said at least two reservoirs are achieved by giving said re¬ servoirs different depths, but preferably this is achieved by constructing said overflows in such a manner that - without overflowing - the one reservoir casu quo the other reservoir can contain e.g. two casu quo three litres of combustible liquid.

Another embodiment of a fire protection system according to the invention is characterized in that said liquid collec¬ ting device is provided with at least five reservoirs abutting against one another, said reservoirs having an overflow interconnecting said reservoirs, whereby a ther¬ mally insulating sealing agent is present between the walls of adjacent reservoirs, and whereby said at least five reservoirs are interconnected by overflows which are de¬ signed in such a manner that liquid leaking from the line into said reservoirs can be carried off to the outside via the various overflows. The spreading of the combustible liquid from one reservoir - via an overflow - to another reservoir has a fire-delaying effect, precisely because the combustible liquid is spread cascade-like over the various reservoirs.

Another embodiment of a fire protection system according to the invention is characterized in that at least one of the outer reservoirs of the liquid collecting device is in communication, via an overflow, with an at least sub¬ stantially closed collecting unit. Preferably each outer reservoir of the liquid collecting device is in communica- tion with an associated collecting unit, whereby the col¬ lecting units in question form a substantially closed channel extending along the liquid collecting device, so that, when combustible liquid present in said outer reser¬ voirs overflows, said liquid will flow into said channel.

Said liquid cannot be ignited in said channel, since there is insufficient oxygen present in the channel.

Another embodiment of a fire protection system according to the invention is characterized in that said fire protection system comprises an agent to be provided in said liquid collecting device, said agent being capable of chemically reacting with the combustible liquid, while water is being formed. Said agent is e.g. a hydropowder to be dispersed in the reservoirs. Said forming of water has a cooling effect, such that the fire started in a reservoir is contained casu quo extinguished.

Another embodiment of a fire protection system according to the invention is characterized in that said fire protection system comprises a body to be provided in said liquid collecting device, said body having a lower specific weight than that of the combustible liquid. In the light of said lower specific weight said body, which preferably has a plate-like configuration, will float on the combustible liquid leaked into a reservoir, thus achieving a reduction of the area over which the fire started in case of a fire can manifest itself in the reservoir.

Another embodiment of a fire protection system according to the invention is characterized in that said body is at least partially provided with a coating keeping out said combusti- ble liquid. Said coating is e.g. a coating of aluminium foil or of a bitumen which is slow to ignite. In particular because of the oil-repellant property of aluminium foil and because of the prolonged fire resistance of aluminium foil the body will for a long time be able to float on the oil leaked into the reservoir.

Another embodiment of a fire protection system according to the invention is characterized in that said fire protection

system comprises an upright wall to be provided at least partially along the edges of said liquid collecting device, said wall being substantially made of a fire-resistant material. Preferably said material is also heat-absorbing. In case of a fire near a power cable in a transformer station the function of said wall is to:

contain the spreading of oil leaking out of the power cable in one field, prevent the transfer of radiating heat from a fire to adjacent power cables,

- oppose the spreading of said fire until the entire quantity of approximately 70 litres of oil normally present in a power cable have burned out completely.

Another embodiment of a fire protection system according to the invention is characterized in that said wall is provided with ϋ-sections to be mounted on the floor, with H-sections to be provided perpendicularly to said ϋ-sections, and with wall panels to be provided between said H-sections. Possibly a power cable in a transformer station may be surrounded by fire resistant wall panels in such a manner that flames produced in case of a fire are either entirely "contained" or led away in such .a manner that the damage to the trans¬ former station is minimized. Preferably the wall panels are detachably provided, so as to facilitate carrying out work on e.g. fields of a transformer station.

Another embodiment of a fire protection system according to the invention is characterized in that said fire protection system comprises sealing means which may be provided between said floor and said U-sections, and between said H-sections and said wall panels.

The invention will be explained in more detail hereafter,

with reference to Figures illustrated in a drawing, in which:

- Figure 1 is a diagrammatic plan view of a fire protec¬ tion system according to the invention, used with a power cable passed into a transformer station;

Figure 2 is a diagrammatic side elevational view of the fire protection system of Figure 1, along the line A - A in said Figure;

- Figure 3 is a diagrammatic perspective view of a liquid collecting device used in the fire protection system shown in Figure 1;

- Figure 4 is a perspective view of a reservoir of the liquid collecting device of Figure 3;

Figures 5 and 6 show a few details of the fire protec- tion system illustrated in Figure l;

- Figure 7 very diagrammatically illustrates a number of reservoirs according to Figure 4, which are in communi¬ cation with a substantially closed channel.

In Figures 1 and 2 a power cable 2 passed through a wall l of a transformer station, under which power cable 2 a liquid collecting device 3_ in the shape of reservoirs 4 abutting against one another is present (on the floor 5 of the transformer station) . Said power cable 2 is passed through said wall 1 via flange passage tubes 6 provided on either side of the wall 1. The reservoirs 4 are provided with overflows whose construction is such that oil leaking out of the power cable 2 and into the reservoirs 4 is led out in the direction indicated by the arrows - via the overflows present between said reservoirs 4. Along the edges of the liquid collecting device 3 an upright wall 7. of a fire resistant material is provided. Said wall 1_ is provided with U-sections 8 secured on the floor 5 by means of e.g. anchor bolts, with H-sections 9 mounted at right angles to said U-sections, and with detachable wall panels 10 provided

between said H-sections 9. A rubber sealing 13 is present between the floor 5 and the U-sections 8.

Figure 3 shows a perspective view of the liquid collecting device 3. with reservoirs 4 of Figures 1 and 2. Between a few reservoirs 4 there are provided overflows 11. Possibly a fire resistant tape 12 is provided around the power cable 2, so as to protect the power cable 2 and to delay the leaking out of oil-

Figure 4 shows a perspective view of a liquid reservoir 4 with overflows 11 having different constructions.

Figure 5 shows a larger-scale view of the detail indicated by means of a dotted circle 14 in Figure 1. Between the walls of adjacent reservoirs 4 there is provided a heat- insulating sealing means 15 (Figure 5a) , whilst the various reservoirs 4 are connected together by means of a clamping section 16 (Figure 5b) .

Figures 6a and 6b diagrammatically show a plan view and a side elevational view respectively of the mounting of a wall panel (10) in an H-section (9) and a U-section (8) respec- tively by means of a nut (17) .

Figure 7 very diagrammatically shows that the outer reser¬ voirs 4 of the liquid collecting device are in communication - via overflows 11 - with a channel 18 extending along said liquid collecting device.

It is noted that a fire protection system according to the invention cannot only be used with power cables passed into a transformer station, but also with industrially used hydraulic lines or fuel lines and the like.