AU3297702A - Protective fire blanket - Google Patents

Description

1 PROTECTIVE FIRE BLANKET FIELD OF THE INVENTION This invention relates to protective fire blankets intended for use by persons engaged in fighting fires in forests, grasslands and other open spaces.

BACKGROUND OF THE INVENTION One of the greatest dangers to persons fighting wildfires or bush fires is that created by an unexpected wind change or other unpredicted phenomena. In such circumstances the firefighters can S* find themselves surrounded by flames generating intense heat, and deadly smoke and fumes. Many people have lost their lives in such conditions, as they have no safe way of escape.

It is known that the most dangerous period lasts for a relatively short period of time. High radiant heat loads may last for up to 10 minutes, while direct flame contact will be for less than 2% of the total time.

One of the best means to survive such conditions is to seek or create shelter. Most firefighters remain in the cabin of their vehicle for as long as possible, and modern vehicles incorporate a water screen to extend this safe period.

However under severe conditions the truck may catch fire and the firefighters are forced to flee into the open. At such times or when the firefighter is caught in the open away from his vehicle he requires a portable means of creating a shelter. One such method is a blanket. This blanket to be successful must protect the firefighter from heat transfer, both radiant heat and direct flame impingement. Furthermore it must be durable, robust and not unduly heavy.

Previous attempts to provide a satisfactory blanket have concentrated on using heavy woollen cloth or laminated aluminium foil combinations. Unfortunately both of these approaches have 1 proved unsuitable in the conditions described above. The laminated foil shelters are excellent in radiant heat load situations, but fail if subjected to direct flame or burning debris. Adhesives used will burn, giving off noxious gases which may be fatal to the firefighter under the shelter.

Woollen blankets also pose a threat to the person sheltering under them. Firstly, radiant heat passes through them rapidly, causing life-threatening heat exposure to the body underneath, and secondly, direct flame impingement can ignite the woollen blanket, releasing deadly cyanide gas. A wetted blanket will produce higher levels of dangerous gases and in greater quantities than a dry blanket.

15 OBJECT OF THE INVENTION The object of the invention is to provide a blanket that is capable of providing protection or shelter to fire fighters under the most severe expected fire conditions.

Preferably the invention should avoid the disadvantages of the previous solutions.

e* SUMMARY OF THE INVENTION One form of the invention is a blanket that includes a layer of glass or silica matt sandwiched between two layers of woven glass cloth.

.An alternative form of the invention is a means of constructing a multi-layer blanket by sewing the layers together with a fire resistant thread.

BRIEF DESCRIPTION OF THE INVENTION The present invention will now be described with reference to the figures in which:- FIG.1 shows a perspective view of the blanket of the present invention with the stitching removed in one corner and the inner layer exposed.

FIG.2 shows one embodiment of the part cross section A.

FIG.3 shows an alternative embodiment of the part cross section

A.

2 DETAILED DESCRIPTION OF THE INVENTION The invention is predicated on the discovery that by using a multi-layered arrangement it is possible to produce a blanket that I provides protection against both direct flame exposure and radiant heat exposure.

It was found that glass fibre woven cloth can provide protection against direct flame impingement and knitted glass or silica matting can provide protection against thermal heat transfer.

It is preferred that the knitted mat be located between two layers of woven glass fibre cloth as this increases the overall *..durability of the fire blanket. Furthermore this arrangement 15 avoids the need to correctly orient the blanket so that the woven cloth side faces the heat source, be it radiant heat or direct flames.

Preferably the glass fibre cloth used in the blanket should be S. 20 tightly woven for this provides greater heat or flame resistance e for a given thickness of cloth.

Preferably the matting should be knitted matting as this increases the durability and the thermal effectiveness of the blanket.

Preferably the blanket will be made with a layer of knitted matting positioned between two layers of tightly woven glass fibre cloth.

As glass fibre can irritate the skin and as glass fibres may be damaging to the lungs, it is preferable to entrap the fibres using a suitable sealing agent such as silicone rubber. One or both sides of the glass fibre cloth may be coated with the sealing agent. In one form of the invention the silicone rubber sealing agent will incorporate an aluminium powder to create a reflective surface, thereby increasing the resistance of the blanket to heat transfer.

Due to the hazards of using an adhesive to fix the layers of the 3blanket together it is preferred to sew the layers of the blanket together with a fire resistant thread. The sewing thread must withstand the heat source without allowing loss of integrity of the blanket.

In one embodiment of the invention the sewing thread will be glass fibre, Kevlar fibre or stainless steel or a combination thereof.

When the blanket is not in use it should be capable of being rolled up to minimise encumbrance. Alternatively, the blanket should be capable of being folded in a concertina fashion which will allow for fast deployment in the field. The materials used should be S. such that the blanket is pliable, and when in use will drape over the user to form a protective envelope.The preferred materials allow this to occur.

S. It is envisaged that the blanket should have some means for keeping the blanket rolled up when not in use. In one embodiment 20 of the invention the blanket will include closing straps for keeping the blanket in a rolled up configuration. Such closing straps should be formed from the same material as the two outer layers of the blanket and be sewn to the blanket such that they can be easily made to meet together when the blanket is rolled up. Hook 25 and loop material such as Velcroo tape could be used to keep the blanket rolled up when not in use.

In an alternative embodiment of the blanket the blanket may be encased in a suitable bag in its folded up form. This bag should incorporate a rapid means of release of the blanket from the bag ready for deployment. One such means of release is either a zip fastener or Velcro' tape.

The protective blanket should be pliable due to the materials proposed for use in the blanket. This will allow it to be rapidly unrolled and deployed. The blanket should drape smoothly over the user, forming a protective covering against surrounding heat flux. This covering must be large enough to prevent radiant heat or flames impinging directly onto the person's body or limbs.

4 The preferred dimensions of the blanket should be at least 2000mm x 1600mm, to provide a safe enclosure for an average fire fighter when deployed on the ground. These dimensions are approximate only and do not form a critical part of the invention. Other dimensions may be acceptable and may be used.

To assist in understanding the invention the invention will now be described with reference to the accompanying drawings that show one example of the invention.

With reference to figure 1, a preferred form of the blanket (1) is shown having at least three layers, the first and third layers of silicone coated tightly woven glass fibre cloth (2) and respectively, and a second inner layer of knitted 15 incombustible matting S. The edges of the blanket may have a rolled edge as shown in S figure 2 for a neat finish. An alternative edge treatment is a simple rough cut edge such as that shown in fig 3. In both cases 20 the layers would be stitched through S with a fire resistant thread.

The knitted matting preferably has a mass of at least 1000gms/m 2 The thickness of the knitted mat should be between 25 3mm and 10mm. The glass or silica content of this mat should be at least 95% pure and the shrinkage when exposed to a temperature of 1000°c for 5 minutes should be less than 5% in any direction.

The silicone rubber coated woven glass cloth should have a nominal weight of between 150gms/m 2 and 300gms/m 2 PRELIMINARY TESTING Samples of various proposed materials were subjected to testing with a high temperature propane gas flame. A hand held pyrometer was used to establish the temperature of the flame at the surface of the materials being tested.

5 Test 1 Two layers of woven glass fibre cloth of 400d/m 2 Duration(s) Face Temp. Reverse Temp. Comments (oC) (oC) 1050 313 Reverse scorched 1050 555 Reverse blistered 395 280 Face scorched 395 300 Face side scorched The tested sample is unsatisfactory for use.

Test 2 Two layers of woven glass fibre cloth of 400g/m 2 with inner layer of aluminium foil of 85g/m 2 Duration(s) Face Temp. Reverse temp. Comments

(OC)

10 1135 186 Face disintegrated 1135 262 Face disintegrated and foil damaged Test results superior to Test 1, but still unacceptable.

Test 3 Two layers of woven glass fibre cloth of 400g/m 2 with inner layer of knitted silica matting 2000g/m 2 15 O20 Duration(s) Face temp. Reverse temp Comments

(OC)

410 39 No damage 410 63 No damage 120 410 63 No damage 180 410 82 No damage 210 410 83 Minor scorching on face side only.

Test results indicate that this combination should meet tests set out by Australian Fire Authorities and should be subjected to further detailed testing.

INTERNAL TESTS Specimens of the materials described in the invention were subjected to extensive testing in an apparatus similar to that described in International Standard ISO 9151-1995 at various 6 heat flux densities ranging from 40kW/m 2 to 115kw/m 2 A summary of the internal testing is set out below.

HEAT TRANSMISSION TEST RESULTS (NAKED FLAME AT 1300"c) SAMPLE DESCRIPTION: 3-layer fire blanket comprising two outer layers of aluminised woven glass cloth with inner layer of fire resistant matting.

HEAT FLUX DENSITY: 80kW/M 2 TEST RESULTS TEMPERATURE RISE (sec) SPECIMEN NO TIME TO 12"c TIME TO 24°c TIME TO 1 22 35 110 2 21 33 97 3 30 51 121 4 25 42 131 29 45 135 6 28 42 105 HEAT TRANSFER INDEX: HTI 41. HTI HTI 24 12 S. S

SSS

HEAT TRANSMISSION FACTOR: 0.17 80kW/M 2 HEAT FLUX VISUAL REPORT 1. No ignition took place in any specimen.

2. No melting or dripping; no hole formation.

3. Face layer surface was brittled.

25 4. Second layer slightly scorched.

Tests carried out February 2002.

Ambient temperature 25°c to 28°c.

SEAM TEST The sewing line was tested for integrity at 80kW/m 2 heat flux for 6 mins. No loss of integrity of the blanket resulted although the stitching was charred.

ANNEXE A HEAT RESISTANCE TEST OVEN TEMPERATURE: 280°C DURATION: 5 minutes The sample was suspended in an oven for 5 mins at the specified 7 temperature.

RESULTS

1. No ignition took place 2. No melting; no hole formation; no dripping of specimen.

3. No splitting; no delamination of the specimen.

4. No measurable deformation of specimen in any direction.

LABORATORY TESTING Specimens submitted to NATA and UKAS accredited laboratories have exceded the requirements of Australian Fire Authorities and test results are summarised below.

SAMPLE: (All 3 Tests) TEST REPORTS One 3-layer assembly comprising Fire Blanket Material Aluminised Finish Knitted Silica Material Fire Blanket Material Aluminised Finish Test I Test Method Pretreatment ISO 6942:1995. Method B using a heat flux of 40KW/m2 Fire Technology Services (UK) None (tested in the 'as received' condition) Summary of Results: Date of Test: Laboratory Temperature: Laboratory Relative Humidity: 1st March, 2002 210C 36% Results Obtained t t, 11s Transmission Factor 0.23 (23%) Specimen 1 Specimen 2 Specimen 3 Time to s 28 29 28 Time to s 39 40 Difference t, s 11 11 12 Transmitted heat flux density, kW/m 2 9.3 9.3 8.8 Test 2 Test Method EN 532-1994 (10 Second Ignition) AWTA (Melbourne) Summary of Results: Specimen After Flame ime (Sec) After Glow Time (Sec) Length 1. 00 00 2. 00 00 3 00 00 Width 1 00 00 2 00 00 3. 00 00 Mean 00 00 Observations: No hole developed No flaming or molten debris No flame reaches upper edge or vertical edge of specimen 8 Test 3 Test Method ISO 9151 1995 AWVTA (Melbourne) Summary of Results:- I_ ime to 12 doac Temoerature Rise (s) lime to 24 deac Temnoratirn Rina I~i Spec 24.0 I28.3 Spec 2 -18.9 125.9 Spec 3 22.5 I31.4 HOe Transter Index: HTI 24 HTI,2 7

I

Observations: 1 st Layer 2nd Layer 3rd Layer Scorched Scorched No Damage A set of non-limiting claims will now be proposed which define one aspect of the invention.

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Claims (11)

1. A fire blanket including a layer of glass fibre cloth and a layer of glass fibre or silica matting.

2. A fire blanket of claim 1 having tightly woven glass fibre cloth.

3. The fire blanket of claim 2 having knitted silica or glass fibre mat.

4. The fire blanket of any one of claims 1 to 3 wherein the blanket includes a layer of silica or glass fibre matting positioned between two layers of glass fibre cloth.

The fire blanket of any of claims 1 to 4 wherein the glass fibre cloth is coated on one or both sides with silicone rubber.

6. The fire blanket of claim 5 wherein the silicone rubber incorporates an aluminium powder to increase the reflectivity of the outer surface of the cloth.

7. The fire blanket of any one of claims 1 to 6 wherein the layers are sewn together with a fire resistant thread.

8. The fire blanket of claim 7 wherein the thread is glass fibre, Kevlar fibre or stainless steel or a combination thereof.

9. A means for constructing a multi-layer fire blanket by sewing together the layers thereof with a fire resistant thread.

10. The means of claim 7 wherein the thread is glass fibre, Kevlar fibre or stainless steel or a combination thereof.

11. A fire blanket substantially as hereinbefore described with reference to the figures. Daled this 5th day of April, 2002. MALCOLM E. GRACE 10