FR2782781A1 - Safety shut-down system for building ventilation installations with two or more extraction fans, comprises central controller switching out all fans if one fails - Google Patents

Abstract

In a typical installation, stale air is drawn from vents (7) in each room (2) into rising ducts (6), exhausting through extraction cowls (3,4) on the roof (5). The necessary pressure drop is naturally induced by venturi action inherent in the cowl design, but usually induced draught fans, driven by electric motors, are incorporated. Where more than one duct is provided, a motor, or fan, break-down at one extraction point is likely to cause stale air to be drawn into some rooms by a siphoning effect. Such a break-down is detected by comparison of pressure measured by sensors (9,10) in each cowl (3,4) connected (12,13) to a central controller (11) on or under the roof. The controller, connected to the building electrical supply, controls each fan motor through further connections (14,15). On detecting the abnormal pressure condition, the controller trips all the fan motors and the system reverts to operation on natural draught. Each cowl comprises an upper enclosure, containing the motor, supported by vertical legs on a base section centered on the duct end. A vertical-axis centrifugal fan operates in the space between conical surfaces fixed under and over, respectively, these sections.

Description

The invention relates to a security device for systems

  evacuation of gaseous fluid, in particular gas

rejected or fumes.

  Static extractors are already known for rejecting

  gaseous fluid, intended to be installed on buildings.

  Such extractors are for example of the type comprising a lower element, an upper element, spacers for rigidly holding the two coaxial elements spaced apart from each other, so as to define a space between them, and comprise a conduit passing through the 'element

  lower and opening into space.

  The lower and upper elements are limited by conical or frustoconical side walls, so that said space has, in axial section, a general shape of venturi or convergent / divergent, along a direction

  radial orthogonal to the general axis of the device.

  The conduit makes it possible to capture and channel the gases or fumes, which exit from this conduit through its upper end generally situated at the upper limit of the lower element, at the very place of the space in the form of a venturi. The gas or smoke flow is then diverted and entrained in this passage towards the outside of the system and the atmosphere

  outside. The presence of wind accelerates this process.

  Documents FR-A-2 658 271, FR-A-2 374 591, EP-A-0 641

  973 describe such static systems.

  The efficiency of these static extractors can be improved by adding one or more air induction devices, of the fan type, in communication

  with the air exhaust ducts.

  Fluid evacuation systems are also known

  gas using stato-mechanical extractors.

  These systems, which generally take the form of the static extractors described in the above, further include a centrifugal turbine having a motor and at least one blade arranged in the free space between

  the upper and lower element.

  Such dynamic systems make it possible to significantly improve the evacuation of the gases or fumes discharged by

the rotation of the blade (s).

  Such stato-mechanical systems are for example described in documents FR-A-2 709 534, FR-A-2 514 469, FR-A-2

755,505.

  Several static or stato-mechanical extractors can thus be arranged, generally on the roof of a building, to ensure the ventilation of all of the

parts of this building.

  Stato-mechanical extractors are connected, via common air exhaust ducts, with the rooms to be ventilated. However, such an installation has drawbacks, in the event of a breakdown, for example by deterioration of the turbine or engine shutdown, of one of the

Stato-mechanical extractors.

  In such a situation, the extractor returns to a static operating mode by venturi effect, and a lower vacuum is installed at the level of the extractor operating statically and the evacuation conduits communicating with it, compared to the depression existing at the level of the other extractors - and the evacuation conduits

  correspondents - dynamically operating.

  This difference in vacuum can cause backdrafting of the gases and fumes into the rooms,

  siphoning in common evacuation pipes.

  Similar siphoning phenomena can occur when one of the fans of the air induction devices installed with static extractors stops,

for example due to a breakdown.

  The invention aims to remedy this drawback by proposing a safety device for gaseous fluid discharge systems comprising extractors

stato-mechanical or static.

  To this end, the safety device for the evacuation system of gaseous fluids of the types comprising at least one static extractor and an air induction device provided with at least one fan or comprising at least one static mechanical extractor provided a centrifugal turbine and at least one blade, the static or stato-mechanical extractor or extractors communicating via one or more evacuation ducts with one or more parts to be ventilated, comprises means for detecting stopping one of the static mechanical extractors or one of the fans of the air induction device, the detection means being connected to common means for controlling the stopping of the static extractor (s) mechanical or ventilator (s) of the air induction device. According to other characteristics, the detection means

  include at least one pressure sensor.

  According to one embodiment, the pressure detector is placed in the vicinity of the blades of the centrifugal turbine of a statomechanical extractor or in the vicinity of a fan.

an air induction device.

  Thus, when a pressure detector registers a drop in vacuum due to the stopping, for example, of the turbine of a statomechanical extractor placed in its vicinity, the common control means cause

  stopping the other stato-mechanical extractors.

  In this way, all the static mechanical extractors go into static operating mode, thus avoiding

a siphoning of stale air.

  According to other characteristics, the common means of controlling the stopping of the stato-mechanical extractor (s) or of the ventilator (s) of the air induction device

  include an electrical control box.

  The safety device according to the invention is suitable for use with the static-mechanical or static extractors described in the documents indicated above and

  the contents of which are incorporated herein by reference.

  The invention will be better understood in the description which

  follows, with reference to the appended figures.

  FIG. 1 represents a schematic view in partial longitudinal section, of a building equipped with a system for discharging gaseous fluids, and provided with a safety device according to the invention, according to a first embodiment. FIG. 2 represents a schematic view, in partial longitudinal section, of a building equipped with a system for discharging gaseous fluids and provided with a safety device according to the invention, according to another embodiment. FIGS. 3 and 4 represent two schematic views, in longitudinal sections, of two embodiments of the pressure detector according to the invention, installed on a

Stato-mechanical extractor.

  Referring to FIG. 1, a building 1 comprising several rooms 2 to be ventilated is provided with a system

evacuation of gaseous fluids.

  The evacuation system of gaseous fluids comprises two stato-mechanical extractors 3, 4 arranged on the roof 5 of the

building 1.

  The static mechanical extractors 3, 4 communicate via a main evacuation duct 6 and secondary evacuation ducts 7 with the parts 2 to be ventilated. When the extractors 3, 4 are in mechanical operation, the stale air is extracted from the parts 2 via the secondary evacuation conduits 7 then

  main 6, in the directions of arrows F1 and F2.

  The stale air is then expelled outside the building 1

  by stato-mechanical extractors 3, 4.

  Stato-mechanical extractors are fitted with a device

security 8.

  The safety device 8 comprises two pressure detectors 9, 10 placed on the stato-mechanical extractors

3, 4 respectively.

  In FIG. 1, the pressure detectors 9, 10 are connected to a control unit 11 via electrical connections 12, 13, and to a source

  power supply (not shown).

  In Figure 1, the control box it is placed on the

  roof of building 1, for the clarity of figure 1.

  It goes without saying that the control unit 11 can be placed inside the building. The control unit 11 is itself connected by electrical connections 14, 15 to the motors of the static mechanical extractors 3, 4 and to an electrical cabinet (not shown) comprising relay contactors corresponding to each static mechanical extractor 3, 4 Thus, when a static mechanical extractor stops, for example the extractor 3, the pressure detector 9 records the pressure variation produced by the return

  of extractor 3 in static operating mode.

  There is then at this instant a greater depression in the main evacuation duct 6 communicating with the extractor 4 in dynamic operation than that existing in the main evacuation duct 6 communicating with the extractor 3 in

static operation.

  The stale air contained in the main evacuation duct 6 communicating with the extractor 3 can then pass, by

  siphoning or suction, in rooms 2.

  To avoid such siphoning, the control unit 11 stops the mechanical extractor 4 via the electrical cabinet. The two static mechanical extractors 3, 4 then operate statically and the stale air can continue to be evacuated to the outside of the building 1 by the venturi effect. Figure 2 shows another embodiment of the invention. In FIG. 2, the same reference numerals designate the same elements as in FIG. 1. According to this variant, the safety device 8 comprises a single pressure detector 9 placed on the static mechanical extractor 3, ensuring for example the evacuations of

  burnt and kitchen gases from building 1.

  The pressure detector 9 is connected, in the same way as for the embodiment shown in FIG. 1, to a

control box 1.

  The motor 40 of the second static mechanical extractor 4 is connected by means of an electrical connection 41,

to the control unit 11.

  The control unit 11 is itself electrically connected to an electrical cabinet (not shown) comprising

  relay contactors corresponding to each static extractor

  mechanical 3, 4 fitted to building 1.

  These relay contactors can be electrically connected

  to the pressure sensor 9 of the extractor 3 or short-

  circuits for extractor 4 not fitted with a pressure detector. According to this variant, when the pressure detector 9 registers an anomaly in the operation of the static mechanical extractor 3, the information is sent to the control unit 11 which cuts, via the corresponding relay contactor of the electrical cabinet, food

  second static mechanical extractor 4.

  The control unit 11 and the electrical cabinet are of the conventional type and will not be described in more detail here. An example of a static mechanical extractor on which a pressure detector is installed is shown on the

Figures 3 and 4.

  Referring to Figures 3 and 4, the stator extractor

  mechanical 3 generally has an axis 100 which, when the extractor is mounted on the chimney, is most often vertical or close to vertical. By convention and for reasons of simplification and better

  understanding, the description is more particularly

  made in relation to the mounted positions. The qualifiers of superior, inferior, etc. must be understood in relation to this mounted position. Similarly, the qualifiers axial, transverse, etc. must be

understood in relation to axis 100.

  The axis 100 is preferably an axis of revolution.

  It is in this variant that the description is made which

  follows. However, in other embodiments, the axis is only of symmetry or even only defines the

  general direction of the extractor 3.

  The static mechanical extractor 3 comprises a lower element 16, an upper element 17; organs 18 of association in the form of spacers of the lower 16 and upper 17 elements so that they are spaced coaxially and facing one another, which spares

  between them a free space 19 for gases or fumes.

  The free space 19 in axial cross section has a general convergent / divergent shape. The device also comprises a conduit 20 for gases or fumes passing through the lower element 16 and emerging through its downstream opening 21 into the space 19 (the qualifier "downstream" means with respect to the normal direction of circulation of the gases or fumes

  when rejected by the device).

  The conduit 20 has a certain axial length. It is intended to be connected to the chimney by means of flanges or the like and communicates with the main duct 6 (not

shown in Figure 2).

  The extractor 3 finally comprises a centrifugal turbine 22 to

radial blades 23.

  According to the embodiment shown, the lower element 16 comprises a lower bottom 24 and a lower cap 25, each of generally frustoconical shape. The lower bottom 24 and the lower cap 25 are crossed coaxially by the pipe 20. The pipe 20 opens at one of its ends, lower hat side 25, in the space 19 between the two elements 16, 17. The other end of the pipe 20 is fixed to the inlet of the fluid

gaseous, namely the chimney.

  The lower bottom 24 and the lower cap 25 are rigidly fixed to each other. The lower cap 25 is provided with an annular lip 26, adjoining a large common base 27, directed downward from said large base 27 and in the extension of the surface of the lower cap 25. The lower bottom 24 comprises a peripheral ring parallel to the frustoconical surface of the lower cap 25. The annular lip 26 comes in direct extension of the frustoconical surface of the lower cap 25 and the connecting spacers 18 rest on

  the frustoconical surface of the lower cap 25.

  The upper element 17 comprises an upper cap 28 and an upper base 29. They are rigidly fixed to each other by a large common base 30. The upper bottom 29 and the upper cap 28 each comprise a transverse peripheral crown 31 , 32 opposite. These O10 transverse peripheral rings 31, 32 define a transverse mounting and joining band for the end of the upper element side 17 of the spacers 18 on the upper element 17. For this purpose each spacer 18 may, for example, have an upper tab connecting, parallel to the transverse strip and extending

in a tangential direction.

  The upper cap 28 can also be provided with a peripheral annular lip 33, adjoining the large base, directed downwards from the large base and in

  the extension of the surface of the upper cap 28.

  This peripheral annular lip 33 comes in extension of the peripheral crown 31 of the upper cap 28 and overlaps the peripheral crown 32 of the bottom

higher 29.

  In the embodiment shown in Figures 3 and 4, the upper bottom 29 has an axial cavity 34 open towards the space 19, housing the blades 23 of a

centrifugal impeller 22.

  The cavity 34 may be provided with an annular lip 35 adjoining the peripheral base 36 and directed upwards. According to an alternative embodiment (not shown), the device according to the invention further comprises means for calibrating the air flow rate extracted by the extractor (s)

fitted with a pressure sensor.

  These calibration means comprise a calibration duct forming an air intake, generally cylindrical, one of the ends of which opens out at the main duct, optionally provided with a grouping hood, in communication with the extractor provided with a pressure detector. he

  The calibration line can be arranged, for example,

  below the lower element of the extractor.

  The other end of the calibration line leads to

outside air.

  Inside the calibration pipe is disposed a disc mounted for rotation about a substantially horizontal axis passing through the center of the disc and parallel to

  the cross section of the calibration line.

  The dimensions of the disc correspond substantially to the cross-sectional area of the calibration pipe, so as to form a closure system for the

said conduct.

  At the upper part of the disc is mounted a threaded rod extending substantially in the direction of the axis

  longitudinal of the calibration line.

  The threaded rod is provided with a mass forming a counterweight, capable of translation along the threaded rod by means of a corresponding internal thread, and

  thus increasing its pendulum effect.

  The adjustment of the displacement of the mass along the threaded rod thus makes it possible to reduce more or less the closure of the calibration pipe and therefore to adjust the resistance effect, due to a pressure drop, to oppose the calibration to calibrate the air flow in the

main line.

  The extractor 3 further comprises a safety device comprising a pressure detector 9. This pressure detector 9 is disposed at the level of the upper element 17

extractor 3.

  According to the embodiment shown, the detector 9 is fixed at the upper bottom 29 of the upper element

  17, by means of a tab 37.

  The pressure detector 9 comprises a tube 38, in particular

  flexible, ending with a connecting nipple 39.

  The connection nipple 39 is arranged at the level of the axial cavity 34, in the vicinity of the blades 23 of the turbine.

22 (Figure 3).

  For example, provision may be made to pierce the axial cavity 34, so as to introduce therein and keep the open end of

the teat 39.

  It is also possible to arrange the connecting nipple 39 in the space 19, in the vicinity of the blades 23, for example below the annular lip 35 of the

axial cavity 34.

  According to another alternative embodiment, the connection nipple 39 is disposed in the duct or chimney 20 of the extractor 3, at a certain distance from the opening 21 of the duct 20, so that the connection nipple 39 is not not located near this opening 21

(figure 4).

  According to yet another alternative embodiment, the connection nipple 39 is disposed inside, for example in the center, of a hood 42 for grouping the evacuation conduits, in the upper part of the hood 42 located

to conduit 20.

  In Figure 4, such a hood 42 is shown. It goes without saying, however, that the extractor 3 can be devoid of

hood 42.

  The pressure detector 9 can also be fixed on the lower element 16, for example at the level of the annular lip 26 of the lower element 16; or at the level of

spacers 18.

  In Figures 3 and 4, the electrical connections of the

  pressure sensor 9 is not shown.

  The pressure detector 9 used in the context of the invention is conventional in itself, for example of the membrane differential type, and is chosen so as to detect

  depressions on the order of about 0 to about 100 Pa.

  For example, the pressure detector 9 can be calibrated to detect low depressions, of the order of approximately

0 to about 20 Pa.

  For example, the detector can be pre-calibrated at approximately 15 Pa on the rise and approximately 10 Pa on the descent, so as to

  detect a differential pressure of approximately 5 Pa.

  The pressure detector 9 can also be calibrated to detect larger depressions, for example

from about 20 to about 100 Pa.

  According to another alternative embodiment of the invention (not shown), the pressure detector 9 is housed in the

  exhaust pipes 6, 7 of building 1.

  In the case of an installation comprising static extractors surmounting ventilation ducts where an air induction device is installed, the detection of an operating anomaly of the evacuation system of gaseous fluids is carried out by measuring the differential pressure existing between a pipe, for example the

  main or primary duct, and the external atmosphere.

  The security device of the invention has been described in

  the above in relation to a stator extractor

  mechanical of the type described in document FR-A-2

709,534.

  It goes without saying, however, that the safety device of the invention can be used with other types of static mechanical extractors, in particular of the type described in documents FR-A-2 514 469 and FR-A- 2,755

  585, the contents of which are incorporated herein by reference.

  The static mechanical extractors described in the foregoing are of the type comprising a motor ensuring the rotation of the blades via a shaft of

transmission.

  It goes without saying that the device of the invention can be used with other types of stato-mechanical extractors, in particular those using a motor of the stator and rotor type.

on which the blades are mounted.

Claims (21)

  1. Safety device (8) for evacuation system of gaseous fluids of the types comprising at least one static extractor and an air induction device provided with at least   a fan or comprising at least one static extractor   mechanical (3, 4) provided with a centrifugal turbine (22) and at least one blade (23), the static or stato-mechanical extractor (s) (3, 4) communicating via one or more evacuation conduits (6, 7) with one or more parts (2) to be ventilated, the safety device (8) comprising means for detecting the stopping of one of the static mechanical extractors (3, 4) or one of the fans of the air induction device, the detection means being connected to common means for controlling the stopping of the stato-mechanical extractor (s) (3, 4) or of the   or fans of the air induction device.   2. Device according to claim 1, characterized in that the detection means comprise at least one pressure detector (9, 10).   3. Device according to claim 2, characterized in that the pressure detector (9, 10) comprises a tube (38), in particular flexible, ending in a nipple of connection (39).   4. Device according to claim 3, characterized in that the pressure detector (9, 10) is of the type membrane differential.   5. Device according to any one of claims 2 to   4, characterized in that the pressure detector (9, 10) is capable of detecting depressions varying between approximately 0 and about 100 Pa.   6. Device according to claim 5, characterized in that the pressure detector (9, 10) is capable of detecting depressions varying between approximately 0 and approximately 20 Pa,   for example a differential pressure of approximately 5 Pa.   7. Device according to claim 5, characterized in that the pressure detector (9, 10) is capable of detecting   depressions varying between about 20 and about 100 Pa.   8. Device according to any one of claims 1 to   7, characterized in that the common control means   include an electrical control box (11).   9. Device according to any one of claims 2 to   8, characterized in rp qli the pressure detector (9, 10) is placed in the vicinity of the blades (23) of the turbine (22) of a statomechanical extractor (3, 4) or of a fan of the air induction device.   10. Device according to claim 9, characterized in that the pressure detector (9, 10) is arranged at the level of the upper element (17) of the stato-mechanical extractor (3, 4).   11. Device according to claim 10, characterized in that the pressure detector (9, 10) is placed at the upper bottom (29) of the upper element (17) of   the static mechanical extractor (3, 4).   12. Device according to claim 11, characterized in that the pressure detector (9, 10) is fixed on the bottom   upper (29) via a tab (37).   13. Device according to any one of claims 3   12, characterized in that the connecting nipple (39) is arranged at the level of the axial cavity (34) of the extractor (3, 4), in the vicinity of the blades (23) of a turbine (22).   14. Device according to any one of claims 3   12, characterized in that the connecting nipple (39) is arranged in the free space (19) of one of the stato-mechanical extractors (3, 4), in the vicinity of the blades (23).   15. Device according to claim 14, characterized in that the connecting nipple (39) is arranged below the annular lip (35) of the axial cavity (34) of one   stato-mechanical extractors (3, 4).   16. Device according to any one of claims 3   8 12; carctric4 on ct mni 1a t connection tinm (39)   is arranged in the duct (20) of the extractor (3, 4).   17. Device according to any one of claims 3   12, characterized in that the connecting nipple (39) is arranged in a hood (42) for grouping the conduits, in the upper part of the hood (42) located towards the conduit (20).   18. Device according to any one of claims 2   8, characterized in that the pressure sensor (9, 10) is arranged in the discharge pipes (6, 7).   19. Device according to any one of claims 1   to 18, characterized in that it further comprises means for calibrating the air flow rate comprising a calibration pipe, one of the ends of which opens at the level of the main pipe in communication with an extractor provided with a pressure detector , the other end of the   calibration line leading outwards.   20. Device according to claim 19, characterized in that the calibration pipe comprises a disc mounted in rotation about a substantially horizontal axis passing through the center of the disc and parallel to the cross section of the calibration pipe, the dimensions of the disc correspond substantially on the surface of the section   cross section of the calibration line.   21. Device according to claim 19 or 20, characterized in that the disc is provided, at its upper part, with a threaded rod extending substantially in the direction of the longitudinal axis of the calibration pipe, the threaded rod being provided with a mass forming a counterweight capable of translation along the threaded rod by   through a corresponding internal thread.