EP0317599A1 - Fireproof sealbag and process for the production of thermo-swelling pad - Google Patents

Abstract

The flame-retardant waterproofing envelope described comprises an outer covering of flame-retardant fabric, such as preferably fiberglass, and in certain cases with an internal covering consisting of an impermeable sheet. The casing is filled with a stuffing material containing a heat-swelling buffer material having 25 to 45% by volume of sand or a fire-retardant granular material of similar specific weight. The stuffing material also comprises 20 to 40% by volume of berlite or other heat-insulating material as the filling material and 20 to 40% by volume of a granular gel based on silicic acid, dried and enriched with water. sodium, as a swelling buffer material. The filling material may in some cases contain 2-5% concrete, in order to improve the density and the filling of the space. In producing the swelling buffer material, the silicic acid-based gel is first prepared by mixing 60-80% water glass and 40-20% of a gel-forming additive, such as sodium chloride. sodium or sodium carbonate, then the gel is dried and the grains are formed. The grains can be prepared by crushing the dried gel or, in some cases, by granulating the still liquid gel in an air jet or by other means.

Description

FIREPROOF SEALBAG AND PROCESS FOR THE PRODUCTION OF THERMO-SWELLING PAD

The present invention relates to a fireproof sealbag provided with an external fireproof fabric cover, preferably made of textile glass, and in given case with a second, internal cover made of damp-proof foil, and filled with a stuffing containing a fireproof filling material and an intumescent material to be primarily used for the temporary and/or permanent fireproof sealing of cable passages or other holes and ducts. Furthermore the invention relates to a process for the production of said intumescent material capable of swelling on elevated temperatures.

Fires preceding the completion of a building frequently occur, mainly in the course of constructions for industrial purpose. Such fires spread rather quickly through the premises within the buildings. The main raison for this is that the holes for the various cables and conduits in the dividing walls are not sealed, thus the fire spreads very quickly by means of the burning cables.

Various means for protecting the passage of the conduits and cables are known already. Such are for example the various bushes, sleeves and devices built into the dividing walls where the cables are led through by embeddings them into a fireproof material. Cable protections like that are described for example in the HU-AS T/25728 and T/25429, or in the DE-PS 28 45 226.

Another way of protecting the passage is to fill the gap between the cables and the wall with thermo-foaming (US-PS 4 493 173), expanding (US-PS 4 376 230) or flame arresting gas generating material (DE-OS 34 19 352).

These passages however, can only be installed after completion of the fitting works, immediately before handing over the building. Until then, the holes along the cable-lines are not covered at all, or they are packed temporarily, only with incidental construction material, e.g. stone- or mineral cotton. This however, is not enough to prevent the fires from spreading after installation of the cables, therefore the passages have to be temporarily sealed. Bags were made for the temporary fireproof sealing, packed into the holes around the cables in order to prevent the fire from spreading. Initially asbestos bags filled with asbestos waste were used. These however, were withdrawn from circulation when it was found out that the asbestos is injurious to health.

Thereafter the bags used for this purpose were made of synthetic foil filled with loose fragments of mineral cotton. However, the synthetic foil cover became easily damaged and instantly melted by the fire, as a result of which, the filling material became dispersed and ineffective. The filling material was dispersed the same way by objects falling down during the fire, breaking up the cover. Due to above shortcomings, the bags disappeared very quickly from the market, and were replaced by the next method where the cover was a strong sail-cloth (canvas) made to be flameproof in certain cases.

This method, however, had many drawbacks as well. Although the bag was much stronger than the earlier one, but even this could not stand the mechanical and thermal loads arising during fire, it got torn or burned and thus the earlier mentioned phenomenon took place. Further drawback was that as a result of the longer heat effect, the mineral cotton shrank at about 700 °C, thus considerably reducing the sealing effect and thereby the fire proofness.

In order to eliminate this drawback, the covering material of the bag partially or completely was coated with thermo- foaming material. However, the drawback of this method was that it had no adequate swelling capacity for penetration into the gaps, moreover the foaming or swelling layer gradually lost its swelling capacity upon the effect of microbes, fungi or moisture.

The main feature of the currently used sealbags is that they are made of textile glass and the filling material or part of it swells upon the effect of heat generated during fire (see DE-PS 35 35 625).

The filling material of this fireproof sealbag is mineral cotton treated as to swell by about 50 volume% at 280 °C. This swelling however, occurs only in open space, which means that when the sealbag is packed into the passage, it is not capable to swell into the gaps and necks, because the compressive strength of the swelling material is low. Hence it does not provide the required tight sealing.

The fireproof sealing pad described in the HU-AS T/26619, is provided with a fireproof cover, in which an easily melting internal cover is arranged and 50-99 mass% of its stuffing is fireproof granular filling material and 1-20 mass's is loose, retarding material inclined to swelling. The fire-proof granular material may be quartzsand, fluedust, swollen perlite or other mineral filling material. The retarding material inclined to swelling contains 15-25 volume% ammonium phosphate, 5-15 mass% polyalcohol and 4-14 mass% carbamide, urotropine and/or melanine.

While these presently used sealbags have many advantages, their significant drawback is manifest in the fact that swelling of the pads takes place at relatively high temperature (at 260-280°C in case of the presently used best solution), when spreading of the fire has already begun and the rate of swelling lags far behind the required value.

The object of the present invention is therefore to profide a fireproof sealbag, which expands its volume upon heat effect at a much lower temperature and to a considerably greater extent, than those used so far, and the compressive strength of the swelling material is sufficiently high to provide tight sealing by penetrating into the gaps of the passages. Further object of the present invention is to provide a process for production of swelling pad for said sealbags.

According to the invention, a fireproof sealbag is provided with an external cover made of fireproof fabric, preferably textile glass and in given case with an internal cover made of damp-proof foil and filled with fireproof filling material, as well as with a thermo-swelling pad, wherein the stuffing contains 25-45 volume% sand or granular fireproof material of similar specific weight, and 20-40 volume% perlite or other heat insulator as filling material, and 20-40 volume% sodium enriched and dried silicic acid gel grains as swelling pad. In given case, the stuffing may contain 2-5 % betonite to improve the density and space filling. The external textile glass layer of the cover may be impregnated with a conventional fireproof paint to improve the fire proofness and to fix the textile fibres against slipping apart.

In the course of producing the swelling pad according to the invention, first silicic acid gel is prepared by mixing 60-80 % waterglass and 40-20 % gelforming additive, e.g. sodiumchloride or sodium carbonate, then the gel is dried and grains are formed. The grains can be prepared by crushing the dried gel, or in given case by granulation of the still liquid gel in air jet or by other means.

Usually the silicic acid gel is dried at room temperature, or max. 80°C for at least 5 hours. The drying requires adequate ventilation.

The sealbag according to the invention has several advantages over the earlier ones:

The pad used in the bags begins to expand its volume at a temperature lower by more than 100°C, than the best versions of the traditional bags.

The pad swells at a lower temperature and to a considerably greater extent than the earlier ones. Upon the effect of heat, it expands to 6-10 times its original volume.

Further advantage of the pad is that upon the effect of heat it becomes a tough, plastic mass in which the gas bubbles cannot burst out. Thus the foaming takes place with higher than the usual pressure. This results usually in great volumetric change and in tight sealing of the passages. Another advantage of the invention is that the stuffing hardens after the swelling and forms a solid, tight wall in the hole to be sealed.

Further advantage of the swelling pad Is that no deleterious gases release during the production or in the case of fire.

Composition of the filling material ensures the optimal mechanical and heat insulation properties of the stuffing.

Further details of the invention will be described by way of examples.

Example 1.

Silicic acid gel was prepared with 80 % waterglass and 20 % sodium chloride. The gel was dried at room temperature for 48 hours, then crushed to about 3 mm diameter grains in a hammer mill.

The grains were put into a furnace, the temperature of which was gradually increased. The grains began to swell at 140°C and were swollen to eight-ten times their original size upon reaching 150°C temperature in 3 minute.

Example 2.

Silicic acid gel was prepared with 60 % waterglass and 40 % sodium carbonate. The gel was dried at 75°C for 8 hours, then broken up between crushing rolls. The size of the obtained fragments was about 4 mm. The grains were put into a furnace and while heating, the grains were swollen to 6-8 times their original size at 150°C.

Example 3.

Fire resistance test was conducted in compliance with the specifications of standard DIN 4102 with traditional sealbags and with those according to the invention. The different sealbags were tested one by one. In the course of the test a 80x40 cm hole in the upper horizontal wall of the furnace provided with burner was sealed with various sealbags in a width of 35 cm. Vertical cable passages were formed in the hole. The passage contained three cables of 40 mm diameter and twelve cables of 8 mm diameter. The latter ones were led through the hole in metal tray.

Thermocouples were attached to different points of the passage to sense the temperatures measured on the outside of the passage (on the surface of the bags, insulation of the cables and on the cables). The test was conducted for 1.5 hour, the furnace was heated from 0 to 1000°C in about half an hour. Some of the tested bags contained swelling pad described in example 1. This represented 25 % of the bags' content, apart from which the stuffing contained 40 volume% sand, 32 volume% perlite and 2 volume% bentonite. These were the samples marked with A.

Composition of the other part of the sealbags (samples B) according to the invention was the following:

- swelling pad according to example 2. 35 %

- quartz flour 35 % - ground fireclay 30 %

The textile glass bag containing the stuffing was impregnated with Alucot T-250 silicone-based fireproof plant.

The test was conducted even with sealbags available in the trade, a certain part of which contained specially treated mineral cotton stuffing (samples C), and the other part was provided with mineral cotton cushion stuffing coated by thermo-foaming material (samples D).

The test results are shown in the following table:

Mark sealbag According to Available in the invention the trade A B A B

Max. temperature measured in the test 1400°C 145°C 203°C 185°C

For evaluation of the table, it is noted, that the standard DIN 4102 permits max. 180°C temperature on the outside of the sealed part during the 1.5 hour test.

The above examples clearly prove that the sealbags according to the invention have more favourable characteristics in every respect than those now available in the trade: the sealing is safe, efficient and durable, in case of fire the padding materials swell socner and to a greater extent than those used earlier, and they form a solidifying, tight wall in the hole.

It is noted that the invention is by no means restricted to the above examples on, the sealbag to the invention can be prepared in several other forms, and by further methods within the scope of the attached claims.

Claims

WHAT WE CLAIM IS

1. Fireproof sealbag preferably with textile glass external cover and in given case with damp-proof internal cover, provided with a stuffing containing a swelling pad, characterized in that the stuffing contain 25-45 volume% sand or granular fireproof material of similar specific weight, and 20-40 volume% perlite or other heat insulator as filling material, and 20-40 volume% sodium enriched and dried silicic acid gel grains as swelling pad.

2. Sealbag according to claim 1, characterized in that the stuffing contains 2-5 volume% bentonite.

3. Sealbag according to claim 1 or 2, characterized in that the fireproof textile is impregnated with fireproof paint.

4. Process for the production of thermo-swelling pad for fireproof sealbags according to any of claims 1 to 3, characterized in that the silicic acid gel is produced by mixing 60-80 % waterglass and 40-20 % gel-forming additive, then the gel is dried and grains are formed.

5. Process according to claim 4, characterized in that the grains are formed by crushing of the dried gel.

6. Process according to claim 4, characterized in that the grains are formed by granulation of the gel.

7. Process according to any of claims 4 to 6. characterized in that sodiumchloride is used as gelforming additive.

8. Process according to any of claims 4 to 6, characterized in that sodium carbonate is used as gelforming additive.

9. Process according to any of claims 4 to 7, characterized in that the drying takes place at max. 80°C temperature with continuous ventilation.

10. Process according to claim 9, characterized in that the drying takes place at room temperature with contiuous ventilation.