FR2650877A1 - Improved collective safety device for a monitored mechanical ventilation/gas installation - Google Patents

Abstract

The invention relates to a collective safety device for a ventilation installation comprising heating appliances 13 equipped with a gas burner and powered with electrical energy, a sheath 23 with a ventilation duct 9 to which the appliances are connected, means 1 for removing the flue gases produced, detection means 25 for monitoring the removal of the said flue gases and sending a signal in the event of an error in the removal, cut-off members 32, 32' for interrupting the operation of the appliances in the event of an error in the removal of the flue gases, and an electrical connection means to transmit the aforementioned signal. According to the invention, the means 47 for connection between the detection means 25 and the cut-off members 32, 32' is continuous and runs inside the duct 9. The invention applies to monitoring mechanical ventilation/gas installations.

Description

 The subject of the invention is a device for improving safety on a controlled mechanical ventilation installation to which gas appliances for producing domestic hot water and / or heating are connected, such an installation being known from technicians in the field under the abbreviated name VMC-Gaz.

 Currently, the texts relating to the ventilation of dwellings and more particularly to the safety measures concerning the evacuation ducts of combustion products emanating from connected gas appliances, such as water heaters, bath heaters or boilers , require that in the event of a breakdown of the mechanical smoke extraction, the evacuation of the latter is ensured by natural draft or that the devices are automatically shut down.

 These texts provide in particular that to avoid any risk of operation of a device connected by residual thermal draft following a fault in the mechanical extraction of the fumes produced, new VMC-Gaz installations must be protected by a collective security equipped with means of detection capable of immediately controlling the stopping of the devices.

 In particular in collective security devices fitted to such installations, the detection means used consist either of a static pressure sensor (or pressure switch) which measures at any time the existence of an appropriate vacuum in the extraction circuit of the smoke, either by a tachometric detector which ensures at all times that the wheel of the exhaust fan rotates at a sufficient speed to maintain the necessary vacuum, the chosen detection means immediately controlling the stopping of the gas appliances connected as soon as the vacuum required on the extraction circuit is no longer reached.

 In practice, the interruption of operation of the devices is currently obtained by means of a cut-off device associated with each device. This breaking device may in particular consist of an electrical ON / OFF switch placed under the control of a relay. And to control this relay, it seems today that the simplest and safest way consists of a connection by electric cables.

 However, it has been observed that the costs of such installations are relatively high, in particular because the electrical connection means used for the transmission of the signals to the breaking devices not only pass through a good part of the housing of the users, but also in the common areas.

 Under these conditions, the object of the invention is to propose an improved collective security device making it possible to reduce the installation costs, which should make it possible to increase the number of security devices installed and therefore thereby make it possible to improve the individual safety of users of gas appliances connected to a VMC-Gaz installation.

More specifically, the invention relates to a collective security device therefore intended to be mounted on a VMC-Gaz installation comprising
- at least one gas appliance for producing domestic hot water and / or heating, fitted with a gas burner,
- a technical sheath inside which passes a VMC-Gas conduit to which the gas appliance is connected for the evacuation of the combustion products emitted by its burner,
means for evacuating said combustion products present in the duct,
- detection means associated with the evacuation means for controlling the evacuation of the combustion products and emitting a signal in the event of an evacuation failure,
- at least one electric cut-off device associated with the connected gas appliance and the detection means, to interrupt the operation of said appliance in the event of a drainage fault,
- an alternating current source for the supply of the connected gas appliance (s), means of evacuation of the combustion products and of the breaking device (s),
- and at least one connection means, of the electric cable type, to ensure the transmission of the signal from the detection means to the breaking device (s),
this device being characterized in that said connecting means uses, of the electric cable type, connects the detection means and the cut-out member (s) while traveling inside said duct.

 I1 appears that by placing the cable in this way, it is practically sheltered from any degradation, over most of its course, thereby improving the overall safety of the device.

 Insofar as, in the conduit where the cable runs, the flue gases also circulate, it will generally be preferable to use a cable having a temperature resistance at least equal to 200 "C (with resistance up to at least 2506C peak for about an hour.) The cable will preferably include two electrical conductors coated with a thermally resistant insulating sheath of synthetic material, which can itself be coated with a protective tape, in particular mechanical protection and which is preferably resistant to the aggressiveness of water which may come from the condensation of water vapor contained in the products of combustion.

 To further increase safety, it has been provided in the invention to use, to connect the various cut-off members to each other and to the detection means, a continuous electric cable which, near each cut-off member, will open out from the conduit and of its technical sheath to connect to the organ in question, without being interrupted.

 In this way, if a connection comes to be disconnected at one of the cut-off members, this will only interrupt the operation of the safety device associated with the device in question.

In order to better highlight all the characteristics and advantages of the invention, we will now describe it with reference to the accompanying drawings given only by way of example and in which
FIG. 1 shows an existing collective security device, currently installed in a building,
FIG. 2 shows a local view of the device of the invention so as to show the connection of the electrical connection cable to a safety box connected to a gas appliance connected to the VMC-Gaz installation,
FIG. 3 illustrates in overview, the device of the invention,
FIG. 4 shows in enlarged local view a construction detail of the device,
- And Figure 5 shows the possible constitution of a transmission cable that can be used.

 First of all, in FIG. 1, a safety device associated with a V.M.C.-Gas installation, as it exists today, is illustrated.

 We see in particular, identified in 1, the extractor box with its fan 3 connected to the power supply (alternating current source constituted by the sector) via the switch 2.

 One or more conduits are connected to the fan casing, such as the duct 5. The casing 1 communicates with the outside or the open air, at 7. The duct 5 is connected on the opposite side to the casing, via the stump 11, to one or more vertical ventilation ducts, such as the duct 9 through which the combustion products emitted by the various gas appliances 13 are discharged, which are connected to the column 9 by their connecting pipe 15.

 It will have been noted that, in a conventional manner, the conduit 9 shown is housed inside a covering sheath, or technical sheath, 23 usually made of masonry materials (plaster plates or tiles, etc.) .

 And each connected gas appliance 13, which is of course provided with a corresponding individual safety device, is equipped with a burner shown diagrammatically at 17, supplied with combustion air and combustible gas by the supply lines marked 19 and 21 respectively.

 To ensure correct operation of each device 13, the smoke extractor box 1 must be permanently maintained under a calculated-required vacuum.

 To verify the existence of this vacuum, the installation is equipped with a security system comprising a detector 25 constituted by a static pressure sensor or by a tachometric detector capable of ensuring that the vacuum is correct in the box.

 Of course, the detector 25 can be housed in the box. And if it is housed next to it and it is a static pressure sensor, an air line 27 will connect it to the box.

 As will be seen, this detector 25 is also connected to the general supply line of the installation (220 or 380 Volts) through a voltage transformer 29 which generally makes it possible to lower the voltage to 24 Volts. A switch 30 allows the transformer to be placed on or off.

 To complete the circuit, the detector 25 is also connected to the subscriber table 31 that each housing has.

 In this table 31 there is a control switch 33, a relay 35 which controls a cut-off member 36, which authorizes in the closed position the electrical supply of the device 13 also connected to the 220 Volts of the housing.

 Table 31 shows a fuse 37 and the subscriber's circuit breaker 39 connected to an individual electric meter 41, which is itself connected to the conductors 43 of the building's riser.

 With such a circuit, when the detector 25 does not detect a fault in the operation of the installation, its contact 26 is closed and each safety relay 35 is energized, its contact 36 which is then closed authorizing the proper functioning of the 'corresponding device 13.

 On the contrary, if the contact 26 is opened as a result of a vacuum fault in the conduit 5, the cut-off signal which constitutes in this case the absence of voltage is transmitted to each of the relays 35, causing the opening of each switching device 36 and therefore the stopping of the devices 13 in question.

 As can be seen from FIG. 1, the electric cables which provide the connection between the detector 25 and the various safety relays 35 on the one hand, and these same relays and the devices 13 connected on the other hand, circulate both inside the different apartments and in the common areas. In practice, these various cables are currently arranged by the installers of the security device, where they can, no precise regulations existing on this subject.

In accordance with the invention, provision has therefore been made to go in the direction of a permanent improvement in security, essentially two provisions
first of all, preferably only a single continuous electric cable will be used between the detection means 25 and the various safety relays, this cable being connected locally to each relay by means of a loop, which will avoid interrupting the cable,
- And moreover, we will run this same cable in the discharge conduit 9, the safety relays 35 being preferably brought close to the corresponding connected device, so that the cable flows as little as possible in housing
In FIG. 2, where part of the device of the invention is illustrated, it can moreover be noted that the relay 35 shown is housed in a safety box 32 disposed very next to a heating device 13 to which it is connected by cable 66 (with connection to the mains) and, on the other hand, the electric cable 47 which connects the various safety boxes and the detection means 25 runs directly in the conduit 9, except near the relays where the cable 47 forms a loop 49, so that it can be connected to each box 32, without being interrupted.

 As illustrated in this FIG. 2, in the safety box 32 are grouped in this case, in addition to the relay 35 under the control of which the safety stop switch 36 is placed, the cut-off member or switch proper functioning test 33 to which an indicator light 65 can be associated making it possible to warn the user of any malfunction of the installation. This indicator 65 and the test switch 33 will be arranged on the front face of the housing so that the switch is accessible by the user of the device, allowing the latter to carry out any periodic check that he deems necessary. necessary.

 It will also be noted that for its connection, each safety box 32 will be equipped with connection plugs 53, 55, such as automatic plugs with tabs.

 In this case, the two plugs are respectively connected to one of the terminals of the test switch 33 (plug 53) and to the relay 35 (plug 55).

According to the invention, the installation of the cable 47 and its connection to each box 32 will preferably take place as follows
At the location of each strain 11 at the top of the conduit, the cable 47 will be lowered into the conduit 9 with the reservation necessary to carry out the various loopings 49 at each level with the various devices 13 connected.

 Close to each extraction mouth 63, the pipe 15 for connecting the corresponding device 13 is disassembled and the cable 47 is recovered by hand or with the aid of a hook. A sufficient loop is formed to allow connection to the connection plugs 53 and 55 of the housing. At the place of connection; the outer envelope of the cable 47 is removed over approximately 10 cm. This cable being preferably two-wire, its two conductive wires 57 and 59 are then stripped over 1 to 3 cm (without cutting the cable) and the cable is then folded back on itself then possibly tinned, so that its first wire 57 is connected to the plug 53 and that its second wire 59 is connected to the other plug 55.

 Thus looping the cable 47 at the location of the boxes 32 has a manifest advantage in that the untimely disconnection of one of the loops of this cable only results in the sole exclusion from the safety circuit of the single device 13 associated, the other devices in the chain remain connected. To improve the security of cable connection, it is still advisable to make leaded connections on each box.

 In view of FIG. 3, it will be noted that the connection of the last box 32 ′ of the chain is somewhat different insofar as, instead of providing a loop for the cable 47, we will simply connect one of the ends of the two wires 57 and 59 which it contains at the two terminals 53, 55 of the last box.

 As for the other end (upper end in general) of the cable 47, it is clear that the wire 57 is connected to the secondary 29a of the transformer 29, while the wire 59 is connected to the contact terminal 26 of the detector 25, the primary 29b of the transformer 29 being itself connected to the 220 or 380 Volts alternating supply line, via the switch 30, - like the conventional connection illustrated in FIG. 1.

Let’s take a look now at Figure 4, which shows schematically how the cable 47 for transmitting the installation stop signal is held in place once installed.
First of all, it will be noted that at the top of the technical sheath 23, the cable opens out from the ventilation duct 9 passing through the vertical lateral wall 61 of the strain 11, thus authorizing the possible disassembly of the inspection plug 12 which closes the upper end of the spuche.

A fixing means 62, such as a cable gland, maintains the cable at the point where it crosses the wall 61. Beyond this, the cable is conventionally connected to the electrical supply via the means of detection of correct operation of the installation.

 Note that in an alternative embodiment, it could also have led the cable 47 directly through the buffer 12 on which it could have been fixed, still by means of a cable gland.

 For fixing the cable, it will also be noted in this FIG. 4 that at the place where the devices connected to the conduit 9 are connected to the latter via the individual extraction mouth 63 and the connecting conduit 64, an orifice 68 is provided so that the cable can exit the conduit 9 bypassing the mouth 63 to connect to the corresponding safety box 32 or 32 '. Note that it is preferable to provide such a bypass of the mouth 63 by the cable, so as to allow disassembly of this mouth with a view in particular to its maintenance.

 At the point where the orifice 68 opens to the outside of the technical sheath 23 (face 23a), a collar 69 will moreover preferably be provided which comes to grip the cable 47 to maintain it. This collar will be applied against said face 2a of the sheath directed towards the interior of the corresponding apartment.

 It should be noted that if the cable 47 must flow inside the VMC-Gaz conduit, that is to say directly in the presence of the combustion products to be evacuated, special safety measures concerning the choice of cable are to be advised .

 Preferably, this cable must in particular be resistant on the one hand to the temperature conditions required by law for the conduits and, on the other hand, to the aggression of the condensed water which may possibly be found in particular in the connecting conduits 63 and 64.

 In particular, and as can be seen in FIG. 5, the conductive wires 57 and 59 of the cable may each be coated in a sheath 70 of thermally resistant electrical insulation, which sheaths may themselves be coated in a protective tape 71 .

 The insulating sheaths 70 can in particular be made of extrasouple extruded silicone rubber, the ribbon 71 possibly being constituted by a mineral ribbon 71a possibly covered by an impregnated mineral braid 71b.

Claims (8)

 1. Collective security device intended to be installed on a gas-controlled mechanical ventilation installation (V.M.C.-GAZ) comprising  - at least one appliance (13) for heating gas and / or for producing domestic hot water equipped with a gas burner (17),  - a technical sheath (23) inside which extends a ventilation duct (9) to which the gas appliance is connected for the evacuation of the combustion products emitted by its burner,  - means (1) for evacuating the combustion products present in the duct (9),  - detection means (25) associated with the evacuation means (1) to control the evacuation of the combustion products and to send a signal in the event of an evacuation failure,  - at least one cut-off device (35, 36) associated with the gas appliance and with the detection means (25) to interrupt the operation of said appliance in the event of failure to evacuate the combustion products,  - at least one source (43,29) of alternating electric current for the supply of the gas appliance (13) -, means of evacuation (1) of the combustion products and of the breaking device (35 , 36),  - And at least one connection means (47) of the electric cable type, to ensure the transmission of the signal from the detection means (25) to the cut-off member (35, 36),  characterized in that the connecting means (47) connects the detection means (25) and the cut-off member (35,36) by traveling inside the ventilation duct (9)  2 Device according to claim 1 characterized in that the electric cable (47), which constitutes said connecting means, has a temperature resistance at least equal to 200 "C and comprises two electrically conductive wires (57,59).  3. Device according to claim 2 characterized in that the two electric conductive wires (57,59) are coated by an insulating sheath (70) made of synthetic material, itself coated by a tape (71) liquid tight and / or mechanical protection.  4. Device according to any one of the preceding claims of the type comprising several gas appliances (13) with each of which is associated a cut-off member (35,36), characterized in that the different cut-off members are connected to each other and by means of. detection (25) by a continuous electric cable (47) which, near each cut-off member, opens out from the sheath (23) and from the duct (9) in order to be connected to the member considered, without being interrupted.  5. Device according to claim 4 in which the detection means (25) are connected to a voltage transformer (29) comprising a primary winding (29b) and a secondary winding (29a), characterized in that the electric cable (47 ) being two-wire, a first end of the first wire (57) is connected to the detection means (25), while the other wire is connected to one of the terminals of the secondary winding (29a) of the transformer, these same wires being , at the place of each cut-off member (35,36) connected either by their second end (last gas appliance (i3) of the chain), or by their loop (49) (from the first to the last appliance) , with two connection plugs (53,55), such as automatic tab plugs, with which said cut-off members are fitted.  6. Device according to any one of the preceding claims, characterized in that 1 '(each) cut-off member (35,36) comprises a switch (36) of ON / OFF of the gas appliance (13) considered, said switch being placed under the control of a relay (35).  7. Device according to any one of the preceding claims, in which the ventilation duct (9) is locally connected on the one hand to a stump (11) and, on the other hand, near each gas appliance (13), to a duct. connecting (64) to which is connected an extraction mouth (63), characterized in that the electric cable (47) -through a side wall (61) of said strain (11) on which it is held by means fixing (62), such as a cable gland, this same cable passing through, near each extraction mouth (63>, a side wall of the conduit (9) and of the technical sheath (23), a collar clamping (69) applied against the outer face (23S) of said side wall of the sheath keeping the previously tensioned cable under tension.  8. Device according to claim 7 characterized in that the electric cable (47) bypasses the extraction mouth (63).