FR2781862A1 - Supple, insulated and fire resistant ventilation or heating duct made from two layers of material with spiral wire windings and insulation between - Google Patents

Abstract

The duct (30) consists of an inner tubular layer (32) reinforced by a spiral metal wire (36) embedded in a fire-resistant material, an insulating layer (40) of constant thickness and containing glass wool, an outer tubular layer (34) which is impermeable to fluids, fire- resistant and has a spiral recess (49), and a sealed coupling (24) for the inner and outer tubular layers. The duct (30) consists of an inner tubular layer (32) reinforced by a spiral metal wire (36) embedded in a fire-resistant material, an insulating layer (40) of constant thickness and containing glass wool which covers the whole periphery of the inner layer but is shorter than its overall length, an outer tubular layer (34) which is impermeable to fluids, fire- resistant and has a spiral recess (49), and a sealed coupling (24) for the inner and outer tubular layers. The coupling is in the form of an adhesive strip of a fire-resistant material incorporating aluminum foil or plastic.

Description

The invention relates to an insulated flexible ventilation or heating duct

  and exhibiting optimal fire behavior. In this area, there is a significant demand for a duct which can be easily and quickly mounted and which above all has excellent fire resistance, that is to say which can be classified as non-combustible or M0 according to the classification of building materials according to their resistance. fire published in the Official Journal of December 11, 1983, page

  10626 NC. According to this classification, each element of the duct and the duct itself

  even must have a higher calorific value (PCS) lower than

600 Kcal / kg (2.5 MJ / kg).

  To date, the proposed ventilation duct comprises the elements shown in FIG. 1. The insulated duct 10 of the prior art comprises an inner duct 12 and an outer duct 14 strictly identical apart from their diameter, the two ducts 12 and 14 being placed concentrically around a longitudinal axis X. These two conduits 12 and 14 consist of a reinforcement in the form of a helical wire 16 of spring type steel positioned inside a wall 18 multilayer, each duct having a very good fire behavior allowing the assembly to be considered as non-combustible according to the

classification M0.

  The annular space located between the two interior conduits 12 and

  outer 14 is filled with an insulating material 20 generally glass wool.

  In order to maintain the fire resistance characteristics at all points of the sheath 10, it is necessary to provide a perfect seal at its ends. To this end, the solution of the prior art represented in FIG. 1 consists in placing an adhesive strip 24 (it is preferable that this adhesive strip has good fire resistance characteristics) which covers both, on the one hand , the outer annular surface of the free end 14a of the outer conduit 14 and,

  on the other hand, the outer surface of the free end 12a of the inner conduit 12.

  In this way, a certain seal is produced at the ends of the conduit 10 between the inner conduit 12 and the outer conduit 14. According to an alternative embodiment illustrated in FIG. 2, certain conduits 10 'of the prior art

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  have, for the sealing at the ends of the conduit 10 ', a metal end piece 22 of revolution. This end piece 22 is cylindrical and widens radially from the inside to the outside at the level of two shoulders 22a and 22b corresponding respectively to the diameter of the inner conduit 12 and the outer conduit. The end 14a of the outer conduit is covered by a peripheral section 22c of the sleeve-forming end piece, the latter being partially covered by an adhesive strip 24 also extending over an annular section.

  of the outer surface of the outer conduit 14.

  However, these conduits 10 and 10 'of the prior art have a number of drawbacks. Indeed, the implementation of the arrangements which have just been described above is not easily achievable, inter alia as regards the optimum positioning of the metal end piece 22. In addition, the sealing produced at the ends of the duct 10 by the adhesive strip (s) 24 constitutes a solution which is not really satisfactory since the zone of continuity to be produced between the external duct 14 and the internal duct 12 extends over a relatively large area. In addition, in the case of the conduit ', the presence of the metal end piece 22 significantly increases the

  cost price of this conduit 10 'which is then no longer flexible over its entire length.

  The completely rigid endpiece 22 can also constitute a weakening element of the free end of the walls 18 of the interior and exterior conduits 12 and 14, for example by localized perforation or tearing of the free end

of said walls 18.

  The invention aims to provide a ventilation duct which does not present the aforementioned problems of ducts of the prior art. According to the present invention, the duct is characterized in that it comprises: - an inner duct having a helical reinforcing wire of metal of the spring type embedded in a flexible wall made of a fire-resistant material which has a helical depression relative to the outer surface of said inner conduit between two adjacent turns of said reinforcing wire, - an insulating layer of substantially constant thickness enveloping

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  the entire periphery of said inner conduit over a length less than that of said inner conduit, - an outer fluid-tight conduit enveloping said insulating layer over a length greater than that of said insulating layer and comprising a continuous flexible wall made of a fire-resistant material which has a helical depression with respect to the external surface of said external conduit, and - connection and sealing means between the ends of said

interior and exterior ducts.

  We see, in fact, that the helical depression of the wall of the outer duct, associated with the flexible nature, that is to say easily foldable or flexible, of this wall, contributes to forming an outer structure of the pre-duct. folded (of the "accordion" type) which maintains a generally circular shape of the duct, especially when forming an elbow; this characteristic allowing, in addition, an axial compression of the conduit reducing its packaging length. Thus, thanks to the pleating of the wall of the outer duct due to the helical depression, it is possible to very significantly improve the quality of the sealing of the duct for a lower cost price than that of the duct of the prior art while retaining mechanical and structural qualities (deformation by pleating) and, also, a fire resistance at least equal to that of the duct

of the prior art.

  According to a preferred characteristic, said external conduit comprises, in addition, a substantially helical fire-resistant reinforcing wire, having a rigidity less than that of the reinforcing wire, easily deformable manually and embedded in said wall, said helical depression having the same not that said wire

  reinforcement and being located between two adjacent turns of said reinforcement wire.

  It is understood that, to a lesser extent than the reinforcing wire of the inner conduit, the reinforcing wire of the outer conduit contributes, in combination with the accordion-like preforming of the wall, to maintaining a substantially

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  circular of the outer duct which allows the duct to have a substantially constant diameter over its entire length, even if it is bent, the wall of the inner duct and the outer duct unfolding or bending very evenly in the bent areas of the sheath . This avoids irregular pleating of the wall of the external duct, that is to say an accumulation of random material in the hollow of the elbow or too great a tension of the wall outside the elbow, which could contribute to crushing too much the insulating layer from which it could result, by a significant reduction in the thickness of this insulating layer, less effective insulation, that is to say an area

weakness in case of fire.

  In this way, the outer conduit can be reduced at its ends, by deformation of the reinforcing wire, to a smaller diameter, corresponding substantially to the diameter of the inner conduit. This reinforcing wire increases the cohesion of the outer conduit, this cohesion also contributing to sufficient fire resistance as well as to a satisfactory tear resistance of the wall of the outer conduit. Thus, it is possible to obtain, at the ends of the conduit, coaxial inner and outer conduits having a substantially identical diameter, which facilitates the implementation of a tight junction at this level. The following advantageous arrangements are also preferably adopted: - said reinforcing wire is made of a ductile material having a diameter at most equal to 1 mm, - the material of said reinforcing wire belongs to the group consisting of steel and the fiberglass, the helix formed by said reinforcing wire has a pitch at most equal to that of the helix formed by said reinforcing wire, - said insulating layer contains glass wool,

  - Said outer conduit has two end portions projecting beyond

  beyond the insulating layer and having a reduced diameter compared to the current diameter, obtained by deformation of the wall of said outer conduit and, if necessary

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  where appropriate, of said reinforcing wire, so that at said end portions the inner surface of said outer conduit is in contact with the outer surface of an end portion of said inner conduit, - said means of connection and sealing include an adhesive strip made of a fire-resistant material which overlaps both said end portion of said inner duct and said end portion of said outer duct, - said fire-resistant material is multilayer and comprises at least one thin sheet of aluminum, said fire-resistant material also comprises at least one sheet of plastic, said plastic preferably being polyester, and the wall of said interior duct is regularly perforated over its entire surface. The present invention also relates to the method of manufacturing a conduit of the aforementioned type, characterized in that it comprises, for each of said interior and exterior conduits, the following steps: - a cylindrical manufacturing head is provided forming a rotary mandrel around a longitudinal axis X0, - a ribbon of fire-resistant material is supplied, - said ribbon is helically wound around said manufacturing head, said ribbon forming an angle a with the transverse plane (Y0, Z0) to said longitudinal axis X0 of

  so as to create a continuous cylindrical wall by overlapping the ribbon on it-

  same, and - one rotates downstream of said manufacturing head at least one wheel rotatably mounted about an axis X0 'parallel to said longitudinal axis X0, the distance between said axes X0 and X0' being less than the sum of the radius R of said cylindrical wall and of the radius RM of said wheel so that said wheel is in radial abutment on said cylindrical wall, which progresses in a helical movement, and generates, by localized deformation of said cylindrical wall, said

helical depression.

  The invention will be better understood, secondary characteristics and

  their advantages will become apparent during the description of the embodiment

  given below as an example.

  It is understood that the description and the drawings are given only for

  indicative and not limiting. Reference will be made to the accompanying drawings, in which: - Figures 1 and 2, already described, are partial views in longitudinal section of conduits of the prior art; - Figures 3 and 4 are partial views in longitudinal section of two alternative embodiments of an air duct according to the present invention; - Figure 5 is a schematic perspective view showing the conduit according to the present invention of Figure 4 with an end piece of the conduit cut away; - Figure 6 is a partial view in longitudinal section of the conduit of Figures 4 and 5 bent substantially 90; and, - Figures 7 and 8 partially show, respectively in longitudinal and transverse directions, the method of manufacturing the conduits

inside and outside.

  Referring to Figure 3, the conduit 30 according to the present invention comprises an inner conduit 32 similar to the inner conduit 12 described above in the context of a conduit of the prior art. This inner conduit 32 comprises a reinforcing wire 36 of spring steel, also called "light steel" defining the nominal diameter DO of the inner conduit 32. This reinforcing wire 36 is embedded in a multilayer wall 38 formed in particular thin sheets of aluminum and at least one polyester rope. The reinforcing wire 36 has sufficient elasticity to allow axial compression of the inner conduit 32 and its curvature and it has sufficient rigidity to constantly maintain the nominal diameter DO. For example, a steel reinforcing wire 36 can be used

  having an elastic resistance (Re) of the order of 170 daN / mm2.

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  The inner conduit 32 is coated with an insulating layer 40, preferably glass wool having a substantially constant thickness over the entire periphery of the inner conduit while being able to present a certain deformation to follow the accordion outline of the outer surface. of the inner conduit 32 or the inner surface of the outer conduit 34 which surrounds

this insulating layer 40.

  According to a known method which will be described in more detail below, the wall 38 is preformed according to an accordion folding by virtue of an initial deformation (helical depression 39) produced by means of a wheel exerting pressure on the wall 38 at which a helical movement was printed so that the thumb wheel presses successively on the entire periphery of the wall 38 following the

  helical shape of the reinforcing wire 36 between two adjacent turns of this wire 36.

  The outer conduit 34 consists of a cylindrical wall 48 of circular section having a multilayer structure similar to that of the wall

38 of the inner duct 32.

  The wall 48 also has a helical depression 49 having a pitch, preferably less than the pitch of the reinforcing wire 36 of the wall 38 of the interior conduit. By this corrugated conformation forming an accordion pre-folding of the wall 48 of the outer duct, a duct is obtained which keeps its circular outer shape of substantially constant diameter, even when bent, so that the property of fire resistance is maintained at a constant level

  all along the duct 30, this level corresponding to that of the outer duct 34.

  Therefore, for the wall 48 of the outer duct 34, a fire-resistant material according to the MO classification is chosen, such as a winding with overlap on itself of a double thickness tape formed by the

  superimposition of a polyester tape and an aluminum tape.

  According to a particularly advantageous variant of the present invention, in accordance with FIGS. 4 to 6, a reinforcing wire 46 is embedded in the wall 48 of the outer conduit 34. This reinforcing wire 46 has a helical shape whose pitch is equal to that of helical depression 49 which

  is interposed between two adjacent turns of the reinforcing wire 46.

  The pitch of the reinforcing wire 46 is preferably less than that of the pitch of the helical reinforcing wire 36. Unlike the reinforcing wire 36, the reinforcing wire 46 does not support the wall 48 because it has a lower rigidity, and preferably very less, than that of the reinforcing wire 36, which results in a low resistance to deformation, a simple manual pressure being able to be sufficient to deform it so that the nominal diameter Dl of the corresponding external conduit

  to the diameter of the propeller formed by the reinforcing wire 46, can be reduced easily.

  However, this wire 46 reinforces the "memory" effect of the circular shape of the external duct 34 already produced by the corrugated shape of the wall 48. Preferably, the reinforcing wire 46 has a tensile strength of less than 60 kg. strength

per mm2 (approximately 60 daN / mm2).

  When the diameter of the outer duct 34 at its ends 34a is reduced, for example manually, the wall 48 and the reinforcing wire 46 fold substantially in an accordion-like fashion along the circumference of the

  ends 34a of the outer duct 34.

  It should be noted that, in a conventional manner, the wall 38 of the inner duct 32 is very regularly perforated over its entire surface so that it is not fluid-tight (FIG. 5). On the other hand, the wall 48 of the external conduit is continuous, which ensures a seal against fluids (for example with hot air or

steam) all along the pipe 30.

  The reinforcing wire 46 can be made of many different materials provided that these are sufficiently fire resistant (classification in category M0 non-combustible). Preferably, a ductile material is chosen, hot or cold, such as steel or fiberglass. Conclusive tests have been carried out with reinforcing threads 46 having the following characteristics:

  - steel wire with a diameter between 0.4 and 0.5 mm.

  So we understand that there are many possibilities for the wire

  reinforcement 46 which may or may not be metallic (fiberglass or even textile fiber).

  According to the present invention, after the insulating layer 40 and the outer conduit 34 have been fitted at the same time around the inner conduit 32, a circular deformation is reduced to reduce the diameter of each end portion 34a of the outer conduit 34 so that these end portions 34a have a diameter Dl 'barely greater than the constant diameter

  DO of inner conduit 32 (Figure 3).

  It then only remains to carry out the sealing at the ends of the sheath 30 by placing an adhesive sealing strip 24 similar to that which has been presented in relation to FIGS. 1 and 2, this strip 24 covering the external surface. of the end portion 34a and the outer surface of a section

  adjacent to the end portion 32a of the inner conduit.

  Thus, the single strip 24 consisting of an aluminized adhesive tape is sufficient to effectively seal the ends of the conduit 30 because the surface

  to be sealed is reduced to a minimum.

  For example, the inner conduit 32 has a diameter DO = 250 mm, the outer conduit has a diameter Dl = 350 mm, the pitch of the wire

  reinforcement 36 is 20 mmn and the pitch of the reinforcing wire 46 is 10 mm.

  According to another particularly advantageous aspect of the present invention, as can be seen in FIG. 6, when, during its installation on site, the duct 30 is bent, the reinforcing wire 46 of the outer duct 34 is sufficient to ensuring the helical "memory" allowing accordion pleating of the wall 48 at the level of the elbow 50. Thus at the level of this zone 50, the external conduit 34 substantially retains its nominal diameter Dl, thus avoiding too great compaction of the insulating layer 40 at the elbow 50 which could create a point of weakness in the conduit 30. With this accordion structure of the outer conduit 34, the wall 48 unfolds regularly at the outside of the elbow 50, without risk of tearing which would be strongly detrimental to the intrinsic qualities of the duct, both in terms of pressure drop and its

fire resistance.

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  The great deformability of the reinforcing wire 46 is not detrimental to the properties of the conduit 30 because, during its assembly, this conduit 30 is bent only once to conform to the geometry of the place, no subsequent manipulation of the conduit 30 being capable of deforming, if only locally, the wall 48 of the outer conduit 34. In relation to FIGS. 7 and 8, we will describe the continuous manufacturing process for the outer conduit 34, a process analogous to that allowing the manufacture of the inner duct 32. A circular manufacturing head 52 with a longitudinal axis X0 comprises cylindrical mandrels 54 regularly distributed along the periphery of the head, inside the cylindrical envelope delimited by the head 52. The axis X1 of each mandrel 54 forms an angle ac with the axis X0 or

  with a generator of the cylindrical envelope.

  A tape 56 composed of an aluminum sheet 58 on which a polyester film 60 is stuck is presented tangentially to the cylindrical surface

  mandrels, in a direction perpendicular to the axis X1 of the mandrels, that is

  i.e. in a direction forming an angle ac with the transverse plane (Y0, Z0)

to said longitudinal axis X0.

  The width of the ribbon 56 and the angle at are chosen so that a part of the ribbon covers part of the outer surface of the section of ribbon forming the preceding turn so as to create a cylindrical wall 62 continues through

  overlap of the ribbon 56 on itself.

  At the exit of the mandrels 54, the wall 62, which advances by performing a rotation on itself, undergoes a pressure deformation generated by a rotating wheel 64, of axis X0 'which creates the helical depression 49 and the wall

wavy 48.

  If necessary, the reinforcing wire 46, placed on the ribbon 56, is wound at the same time as the ribbon 56 and it is arranged so that the wheel presses between

  two adjacent turns of the reinforcing wire 46.

  For example, an aluminum strip 58 of width L1 = 82 nmm supports a polyester film 60 of width L2 = 35 mm laminated back from an il 2781862 distance R1 = 4.5 mm, the reinforcing wire 46 being a 0.4 mm diameter steel wire offset by a distance R2 = 3.5 mm from the edge of the polyester film 60. The angle a is determined by the diameter of the conduit, the width of the strip 56 and the overlap desired from this strip 56 on itself. For example, for a pipe diameter of 100 mm, a strip width 56 of 82 mm and an overlap of this strip on itself of 54 mm, the angle ac is approximately 5 and a pitch p d is obtained. '' about 28 mm before the deformation undergone by

  pressure generated by the wheel 64.

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Claims (11)

  1. Flexible ventilation or heating duct (30), insulated and fire-resistant, characterized in that it comprises: - an inner duct (32) having a helical reinforcing wire (36) of metal of the spring embedded in a flexible wall (38) made of a fire-resistant material which has a helical depression (39) with respect to the external surface of said internal conduit (32) between two adjacent turns of said reinforcing wire (36), - an insulating layer (40) of substantially constant thickness enveloping the entire periphery of said inner conduit (32) over a length less than that of said inner conduit (32), - an outer conduit (34) impervious to fluids enveloping said insulating layer (40 ) over a length greater than that of said insulating layer (40) and comprising a continuous flexible wall (48) made of a fire-resistant material which has a helical depression (49) relative to the surface e xtérieur of said outer conduit (34), and - connection and sealing means (24) between the ends of said   interior and exterior conduits (32, 34).   2. Conduit (30) according to claim 1, characterized in that said outer conduit (34) further comprises a reinforcing wire (46) substantially helical fire resistant, having a rigidity less than that of the reinforcing wire (36), easily deformable manually and embedded in said wall (48), said helical depression (49) having the same pitch as said reinforcing wire (46) and being   located between two adjacent turns of said reinforcing wire (46).   3. Conduit (30) according to claim 2, characterized in that said reinforcing wire (46) is made of a ductile material having a diameter at most equal at 1 mm.   4. Conduit (30) according to any one of the preceding claims,   characterized in that the material of said reinforcing wire (46) belongs to the group   made up of steel and fiberglass. 13 2781862   5. Conduit (30) according to any one of the preceding claims,   characterized in that the helix formed by said reinforcing wire (46) has a pitch at   more equal to that of the helix formed by said reinforcing wire (36).   6. Conduit (30) according to any one of the preceding claims,   characterized in that said insulating layer (40) contains glass wool.   7. Conduit (30) according to any one of the preceding claims,   characterized in that said outer conduit (34) has two end portions (34a) projecting beyond the insulating layer (40) and having a reduced diameter (DV ') compared to the current diameter (D1), obtained by deformation of the wall (48) of the outer conduit (34), so that at said end portions (34a) the inner surface of said outer conduit is in contact with the outer surface   an end portion (32a) of said inner conduit (32).   8. Conduit (30) according to claim 7, characterized in that said connection and sealing means comprise an adhesive strip (24) made of a fire-resistant material which overlaps both said end portion (32a) of said inner conduit (32) and said end portion (34a) of said outer conduit (34).   9. Conduit (30) according to any one of the preceding claims,   characterized in that said fire resistant material is multilayer and comprises at   minus a thin sheet of aluminum.   10. Pipe according to claim 9, characterized in that said fire-resistant material further comprises at least one sheet of plastic, said   plastic material preferably being polyester.   11. A method of manufacturing a conduit according to any one of   previous claims, characterized in that it comprises, for each of said   inner and outer conduits (32, 34), the following steps: - a cylindrical manufacturing head (52) is formed forming a rotary mandrel around a longitudinal axis XO, - a ribbon (56) of fire-resistant material is provided, 14 2781862   - said ribbon (56) is helically wound around said manufacturing head (52), said ribbon (56) forming an angle cc with the transverse plane (YO, ZO) to said longitudinal axis XO so as to create a cylindrical wall ( 62) continues by overlapping the ribbon (56) on itself, and - one rotates downstream of said manufacturing head (52) at least one wheel (64) rotatably mounted about an axis XX 'parallel to said longitudinal axis XO, the distance between said axes XO and XO 'being less than the sum of the radius (R) of said cylindrical wall (62) and the radius (RQ) of said wheel so that said wheel is in radial abutment on said cylindrical wall (62) and generates, by localized deformation of said cylindrical wall, said helical depression (39, 49).