Improvements in ventilators

Abstract

 A controllable fire ventilator has opening springs (13) and dual day-to-day controls one of which is a pneumatically operable piston-and-cylinder unit (20) and the other of which is an electro-magnetic device (30) which retains a keeper plate (33) when the device is energised. The unit (20) may be powered to close the ventilator when the ventilator is open, the control cable (22) carrying the keeper plate (33). Fire response may be by means of a fusible link (35). In an alternative arrangement (see Fig. 3), the electro-magnetic device (30) is incorporated into the cylinder (121) of the cylinder unit and the piston (126) carries the keeper plate (33). A fire switch (140) may open in response to an electrically signalling fire detection system, the cylinder unit (120) being exhausted to atmosphere through its power connection (122) by valve means adjustable only upon operation of a sprinkler system, to avoid ventilator opening in response to false alarms.

Description

[0001] The present invention comprises improvements in ventilators and concerns controllable, fire ventilators which are required to open automatically in response to a fire condition, to vent heat, smoke and/or gases from a building, and to provide selectable day-to-day ventilation upon the operation of suitable controls.

[0002] Such ventilators customarily employ opening means such as a spring or springs, or weights, normally urging the ventilator to open, and releasable retention means releasable in response to the onset of a fire condition, and normally holding the ventilator closed. In this manner, it is ensured that the ventilator opens automatically in an emergency, i.e. when it is required to act as a fire ventilator. To enable the ventilator to be selectively controlled for day-to-day ventilation purposes, the retention means is most conveniently incorporated into the day-to-day ventilator controls and conventionally takes the form of a fusible link which parts at a predetermined elevated temperature to sever the controls and allow the ventilator to open under the action of its opening spring or springs or its opening weight.

[0003] In use of a ventilator of this general kind, a problem sometimes arises in that a failure of the day-to-day controls allows the ventilator to open un­necessarily, such as to permit the escape of warmth from the building and perhaps more seriously to allow rain water to enter the building and spoil articles, such as merchantable goods, stored in the building.

[0004] To mitigate this problem the present invention provides a controllable fire ventilator as hereinbefore described having dual day-to-day controls each capable of holding the ventilator closed, one of the controls being operable to move the ventilator from an open to its closed position, and both controls being operable to allow the ventilator to open.

[0005] Preferably, the dual controls are arranged in tandem and preferably also, the controls are powered controls, each having its own power source.

[0006] Specific embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which :-

FIG. 1 is a cross-section of a ventilator according to the present invention incorporating dual controls;

FIG. 2 is an underneath plan view of the ventilator shown in Fig. 1; and

FIG. 3 illustrates alternative dual controls for a ventilator the present invention.

[0007] With reference now to the accompanying drawings, and first to Figs. 1 and 2, the ventilator of the present example is of the louvred type comprising a frame 10 defining a ventilation opening 11 controlled by a bank of pivotable louvres 12 movable between a closed position, closing the ventilation opening 11 of the ventilator, and an open position allowing the exhaust of heat, smoke and fumes through the ventilation opening. The ventilator may, however, be a single flap or double flap ventilator in which the flap or flaps are movable between a closed position, closing the ventilation opening, and an open position allowing exhaust of heat, smoke and fumes through the opening.

[0008] The louvres 12 are each pivoted to the frame 10 as at 14, for opening and closing movement, in unison, by movement of control bars (not shown) under the action of opening springs 13 connected between the frame 10 of the ventilator and a transverse member 16 inter­connecting the control bars. To this end, the louvres 12 are pivoted to the control bars, which extend along opposite sides respectively of the bank of louvres, by means of louvre ears (not shown) attached to the louvre ends.

[0009] Many different control linkages are known or may be devised for moving a bank of louvres in unison, to open and close the louvres and any system is suitable for the purposes of the present example. The essential feature is to have an opening spring or springs connected between the frame and the control linkage at a suitable point or points. Of course, as is equally well known the control linkage may incorporate instead of an opening spring or springs, an opening weight, the weight, when released, moving under gravity to open the ventilator.

[0010] If the ventilator is a flap ventilator having one or two flaps, the flaps may be arranged to be urged open by springs or weights in any known or convenient fashion.

[0011] Referring again to the accompanying drawings, the louvred ventilator example has dual ventilator controls each capable of holding the ventilator closed. These controls are respectively pneumatically and electrically powered controls and in the present example the controls are arranged in tandem such that if the power supply to one control should fail, the remaining control holds the ventilator closed, and vice versa. The pneumatically powered control, which could be substituted with an hydraulically powered control or a manual control, takes the form of a pneumatic piston and cylinder unit 20 mounted on the framed 10, the cylinder of which is supplied with compressed air by a supply pipe (not shown) to close the ventilator, the piston then being instroked to move the control linkage member 16 via a control cable 22 connecting the piston rod 21 with the member 16, the cable passing around a pulley 24.

[0012] If the supply of compressed air to the cylinder of the unit 20 should fail for any reason the ventilator would normally be opened by the springs 13.

[0013] To prevent this, an electro-magnetic control 30 is provided comprising an electro-magnetic device 31 mounted on the frame 10 and an electro-magnetic keeper plate 33 attached to the cable 22. So long as the electro-magnetic device 31 remains energised, the keeper plate 33 is retained by the device and the springs 13 are not able to open the ventilator.

[0014] If the electrical power supply to the device 31 should fail, the ventilator is unable to open so long as compressed air is supplied to the unit 20.

[0015] There is a double assurance therefore that the ventilator will not open unintentionally due to a power failure for example.

[0016] The piston and cylinder unit 20 may be used to adjust the ventilator to any desired open position between fully open and closed. In order to adjust the ventilator from the closed position to an open position, the electro-magnetic device 31 is de-energised and may be re-energised once the ventilator has been adjusted to an open position in order to hold the ventilator closed once it has been re-closed by operation of the unit 21.

[0017] To obtain an automatic opening in response to the onset of a fire condition the cable control incorporates a fusible link 35.

[0018] The unit 20 and the cable 22 may be connected to close the flap or flaps of a single flap or a twin flap ventilator in any convenient manner, the electro-­magnetic control 30 then holding the flaps closed when the flaps are moved to their closed position.

[0019] Instead of the pneumatic piston and cylinder unit 20, an electric motor driven unit could be substituted, the electric motor driven unit being powered e.g. from a battery powered source and the electro-­magnetic device 31 from an A.C. power source or vice versa.

[0020] Dual day-to-day controls having dual electric circuits both of which must be activated to allow the ventilator to open can be interconnected electrically with an electrically signalling fire detection system and an electrically operated sprinkler system to achieve an earlier response to a requirement for smoke venting whilst avoiding ventilator opening in response to a false alarm arising from the fire detection system alone.

[0021] With reference now to Fig. 3 of the accompanying drawings, the ventilator of the present example may again be of the louvred type as already described. The ventilator may, however, be a single flap or double flap ventilator in which the flap or flaps are movable between a closed position, closing the ventilation opening, and an open position allowing exhaust of heat, smoke and fumes through the opening.

[0022] In any case, an opening spring or springs or an opening weight or weights are provided to open the ventilator.

[0023] The dual controls illustrated in Fig. 3 are each capable of holding the ventilator closed. These controls are respectively pneumatically and electrically powered controls and in the present example the controls are again arranged in tandem such that if the power supply to one control should fail, the remaining control holds the ventilator closed, and vice versa. The pneumatically powered control takes the form of a pneumatic piston and cylinder unit 120 mounted on the frame of the ventilator, the cylinder 121 of which is supplied with compressed air by a supply pipe 122 to close the ventilator, the piston then being instroked to move a control linkage member connected as at 123 to the piston rod 124.

[0024] If the supply of compressed air to the cylinder of the unit 120 should fail for any reason the ventilator would normally be opened by its spring or springs or weight or weights.

[0025] To prevent this, an electro-magnet 30 is provided mounted in, and forming the inner end wall of, the cylinder 121, which is composed of non-magnetically permeable material, a keeper plate 33 being attached to the piston 126. So long as the electro-magnet 30 remains energised, the keeper plate 33 is retained in contact with it by the magnet and the springs are not able to open the ventilator.

[0026] If the electrical power supply to the magnet should fail, the ventilator is unable to open so long as compressed air is supplied to the unit 120 through the supply pipe 122.

[0027] There is a double assurance therefore that the ventilator will not open unintentionally due to a power failure for example.

[0028] The piston and cylinder unit 120 may be used to adjust the ventilator to any desired open position between fully open and closed. In order to adjust the ventilator from the closed position to an open position, the electro-magnet 30 is de-energised and may be re-energised once the ventilator has been adjusted to an open position in order to hold the ventilator closed once it has been re-closed by operation of the unit 120.

[0029] To obtain an automatic opening in response to the onset of a fire condition the ventilator control linkage member may incorporate a fusible link.

[0030] A fire switch 140 is incorporated in the power supply to the electro-magnet 30 to enable the ventilator to open when the unit 120 is exhausted of compressed air through the pipe connection 122 by suitable switching of a pneumatic control valve to place the pipe connection 122 in communication with atmosphere, e.g. in response to operation of an electrically signalling fire detection system or an electrically operated sprinkler system.

[0031] The unit 120 may be connected to close the flap or flaps of a single flap or a twin flap ventilator in any convenient manner, the electromagnet 30 then holding the flaps closed when the flaps are moved to their closed position.

[0032] The magnet 30 is powered from a 24 Volt battery source.

[0033] The dual day-to-day controls (not shown) having respectively pneumatic and electric circuits to power the unit 120 and the magnet 30 respectively must both be switched to allow the ventilator to open. The fire switch 140 can be interconnected electrically with the electrically signalling fire detection system to achieve an earlier response to a requirement for smoke venting by automatic operation of the pneumatic control valve in response to operation of the electrically operated sprinkler system whilst avoiding ventilator opening in response to a false alarm arising from the fire detec­tion system alone.

[0034] Any suitable manually controllable pneumatic valve system may be used to control the supply and exhaust of compressed air to and from the unit 120 to control the day-to-day adjustment of the ventilator. In the same way, an electric switch in addition to the fire switch 140 would be provided to de-energise and then re-energise the electro-magnet 30 for day-to-day opening of the ventilator, the electro-magnet being re-energised to hold the ventilator closed when the ventilator is returned to its closed position by operation of the unit 120.

Claims

1. A controllable fire ventilator which is required to open automatically in response to a fire condition and to provide selectable day-to-day ventila­tion, the ventilator having a spring or springs and/or a weight or weights urging it to open and dual day-to-­day controls each capable of holding the ventilator closed, one of the controls being operable to move the ventilator from an open to its closed position, and both controls being operable to allow the ventilator to open under the action of its spring or springs and/or weight or weights.

2. A ventilator as claimed in claim 1 in which the dual controls are arranged in tandem.

3. A ventilator as claimed in claim 1 or 2 in which the dual controls are powered controls each having its own power source.

4. A ventilator as claimed in claim 1 or 2 in which said one of the controls is a manual control.

5. A ventilator as claimed in claim 1 or 2 in which said one of the controls is a pneumatically or hydraulically powered control.

6. A ventilator as claimed in claim 1, 2, 4 or 5 in which the other control is an electrically powered control.

7. A ventilator as claimed in claims 5 and 6 in which said one of the controls comprises a pneumatically powered piston and cylinder unit.

8. A ventilator as claimed in claim 6 or 7 in which the other control comprises an electro-magnetic device and an electro-magnetic keeper plate retained by the device to hold the ventilator closed so long as the electro-magnetic device remains energised.

9. A ventilator as claimed in claim 8 in which the electro-magnetic device is arranged to be re-energised once the ventilator has been adjusted to an open position by the spring or springs and/or weight or weights.

10. A ventilator as claimed in claims 7 and 8 or claims 7, 8 and 9 in which the electro-magnetic device is mounted in and forms the inner end wall of the cylinder of said piston and cylinder unit, the piston of which carries said electro-magnetic keeper plate, and the cylinder is composed of non-magnetically permeable material.

11. A ventilator as claimed in claim 8, 9 or 10 in which the electrically powered control includes a normally closed fire switch electrically interconnected with an electrically signalling fire detection system so as to be opened upon operation thereof, thereby to de-energise the electro-magnetic device, and said one of the controls is responsive to the operation of an electrically operated sprinkler system.

12. A ventilator as claimed in claim 2, or any of claims 3 to 11, when directly or indirectly dependent upon claim 2 in which the dual day-to-day controls incorporate a fusible link positioned so as to obtain in response to the onset of a fire condition and melting the link, an automatic opening of the ventilator under the action of said spring or springs and/or weight or weights.

Drawing