Patent Description:
Fire suppression systems are safety critical. It is therefore necessary to ensure they are as reliable as possible. For this reason, sprinklers in fire suppression systems typically include a mechanical component, relying on a frangible sprinkler bulb as a type of mechanical fuse that will shatter when exposed to a predetermined temperature which may be indicative of a fire, thereby causing the sprinkler to emit fire suppressant. Such sprinkler bulbs are therefore designed to break and so may be relatively delicate.

However, fire suppression systems may be installed in environments where there is risk of damaging sprinklers and sprinkler bulbs, for example in warehouses, ducts, small spaces, and so on. Fire suppression systems for these environments may therefore be provided with deployable (or "pop-out") sprinklers which are deployed to a ready state in the event that the system detects something that might be a fire. Prior to deployment, the sprinklers may be protected e.g. by being withdrawn into a wall or ceiling. After deployment, the deployed sprinklers must be pushed back to their undeployed (i.e. not deployed) positions ready for the next deployment.

<FIG> show an example of a known fire suppression system <NUM> with deployable sprinklers <NUM>. The operation of system <NUM> is described in more detail below.

After the deployable sprinklers <NUM> are deployed (e.g. as in <FIG>), they need to be reset to their initial configurations (e.g. as in <FIG>). This process is manual and is therefore labour intensive, especially for a large number of sprinklers. Moreover, suppressant from a suppressant source <NUM> is used to deploy the sprinklers <NUM>, and the suppressant will therefore need to be recharged after any sprinkler deployment.

In the interests of safety, fire suppression systems err on the side of sensitivity, and therefore commonly experience "false alarms" i.e. activation despite the absence of a fire. False alarms are particularly burdensome for deployable sprinkler fire suppression systems because they use up suppressant and are labour intensive to reset the system. Improvements in deployable sprinkler fire suppression systems are therefore desirable.

<CIT> and <CIT> disclose sprinklers comprising detachable covers. <CIT> and <CIT> disclose sprinklers comprising telescopic components.

According to a first aspect of the invention there is provided a deployable sprinkler fire suppression system comprising: a deployable sprinkler, arranged to be deployed prior to a suppression event; a suppressant source arranged to discharge suppressant from the sprinkler during a suppression event; a propellant source arranged to supply propellant to the sprinkler to deploy the sprinkler prior to the suppression event; and a supply pipe arranged to supply suppressant to the sprinkler during the suppression event; wherein the system is arranged to deploy the sprinkler by pressurising the supply pipe by supplying propellant from the propellant source to the sprinkler prior to supplying suppressant from the suppressant source.

Thus, only propellant may be needed to deploy the sprinkler, and suppressant may not be used to deploy the sprinkler. That is, the system may be arranged to use propellant to prime the sprinkler ready for a suppression event, without using any suppressant for the priming procedure. For example, during a detection event (an initial detection of a possible suppression event e.g. by a smoke detector) the system may use propellant to deploy the sprinkler. Once deployed, the sprinkler may be in a ready-state to receive and discharge suppressant from the suppressant source. If after deployment and during a suppression event the sprinkler is activated (e.g. it detects a fire by a frangible sprinkler bulb being broken), the system may be arranged to then (and only then) supply suppressant to the sprinkler. The system therefore may not use suppressant to deploy the sprinkler. As such, false alarms (e.g. due to false positive detection events) will not use suppressant to deploy the sprinkler and therefore the suppressant may not need to be replenished after such a false alarm.

The propellant may be a pressurised fluid, and the system is arranged to pressurise the supply pipe to the deployable sprinkler, the supply pipe being provided to supply suppressant to the sprinkler during a suppression event. The system is therefore arranged to deploy the sprinkler by supplying propellant from the propellant source to the supply pipe for the sprinkler prior to supplying suppressant from the suppressant source to the supply pipe. The system may be arranged to deploy the sprinkler by pressurizing the supply pipe using propellant and without using suppressant. The supply of the propellant may be directly to the sprinkler via any suitable arrangement of lines and/or pipes. The system is arranged to pressurise the sprinkler supply pipe using propellant and thereby cause the sprinkler to deploy. The system is arranged pressurise the supply pipe prior to supplying suppressant to the supply pipe. The system may be arranged to deploy the sprinkler without using suppressant. The propellant may not be supplied to the sprinkler via the suppressant source. The system may be arranged to deploy the sprinkler by supplying compressed fluid to the sprinkler supply pipe. During a suppression event, propellant may precede suppressant from the sprinkler.

The sprinkler is deployable in the sense that it may be arranged to transition from a first, undeployed position in which is it not ready or able to discharge suppressant (e.g. retracted into a wall or ceiling), and a second deployed position in which is ready and able to detect a fire and discharge suppressant (e.g. projecting from a wall or ceiling). The sprinkler may not be able to detect a suppression event in the undeployed position, and/or may be able to detect a suppression event in the deployed position. The sprinkler may be exposed in the deployed position and may be unexposed and/or protected in the undeployed position. The deployable sprinkler may be a pop-out sprinkler. The sprinkler may comprise a frangible sprinkler bulb that is protected when the sprinkler is in its undeployed configuration and is exposed for detecting a fire when the sprinkler is in its deployed configuration.

The system may comprise a vacuum pump operable to retract the sprinkler from a deployed position. The vacuum pump may be operable to de-pressurise the sprinkler supply pipe arranged for supplying fluid to the sprinklers. The vacuum pump may be operable to reduce pressure within the sprinkler supply pipe to below ambient pressure outside the system and thereby move the deployable sprinkler into its first undeployed position. Put simply, the vacuum pump may be arranged to suck the sprinkler back into its undeployed (non-ready) position. Although this feature of the invention is described using a vacuum pump, any suitable pressure-reducing mechanism for retracting the sprinkler may be used.

The system may comprise a compressor operable to recharge the propellant. The compressor may be arranged to recharge only some of the propellant in the system (e.g. in a first propellant source or in a second propellant source), or the compressor may be arranged to recharge all propellant sources within the system. The compressor may be an integral part of the system. The system may comprise a one-way valve arranged in a pipe between the compressor and the propellant source to permit fluid flow in only one direction. The compressor may be controlled by a system controller, which itself may be an integral part of the system. Although this feature of the invention is described with reference to a compressor, any suitable mechanism for recharging the propellant source(s) may be used.

The propellant may therefore be recharged after it has been used to deploy the sprinkler. Thus, in the event of a false alarm, the propellant that was used to deploy the sprinkler may be simply replenished. Since the suppressant is not needed to deploy the sprinkler, it is simple to restore the fire suppression system to a ready state in which it is ready to deploy the sprinkler again and subsequently deploy suppressant should a detection event and a suppressant event occur.

The propellant may be compressed air. The propellant may be recharged using the compressor to compress ambient air and supply it to the propellant source, and hence it may be straightforward to replenish the propellant. The propellant may therefore be flammable. The propellant may contain oxygen. The system may comprise a mechanism for removing oxygen from the compressed air and thereby reducing its flammability. Alternatively, the propellant may be non-flammable, and may be any other suitable compressed fluid and/or gas such as nitrogen. The propellant may be inert. The propellant may be a gas and the suppressant may be a liquid. The propellant and suppressant may each be any suitable substance.

The system may be arranged to use propellant to supply suppressant from the suppressant source to the sprinkler during a suppression event. Thus, the suppressant may be supplied to the sprinkler by propellant (e.g. compressed air) which may be propellant from the propellant source, or may be propellant another, second propellant source.

The system may be arranged to use propellant from the propellant source to discharge the suppressant. However, although only a single propellant source could be used, two separate propellant sources may be used instead, the first propellant source for deploying the sprinkler during a detection event, and the second propellant source for supplying suppressant to the sprinkler during a suppression event. The propellant source may therefore be a first propellant source and the system may comprise a second propellant source for supplying propellant for discharging the suppressant. The second propellant source may be a dedicated source for supplying suppressant to the sprinkler during a suppression event. The first propellant source can therefore be depleted without risk of there being insufficient propellant left to subsequently discharge the suppressant. The first propellant source may be sized to contain only enough propellant to charge (i.e. pressurise) the sprinkler supply pipe and deploy the sprinkler, but may not be larger than that. Thus, during a detection event the system may only need to open a single valve to deploy the sprinklers. The (first) propellant source may be sized to pressurise the sprinkler supply pipe to a pressure of approximately <NUM> bar (<NUM> MPa).

The propellant in the second propellant source may be an inert, non-flammable fluid. The propellant in the second source may be the same as the propellant in the first propellant source, and may be compressed air. The compressor may be arranged to recharge both the first propellant source and the second propellant source e.g. by compressing ambient air and supplying it to the propellant sources. Both propellants may be compressed air, or the propellant in the first propellant source for deploying the sprinklers may be compressed air, and the propellant for discharging the suppressant may not be compressed air. The propellant in the second propellant source may instead be an inert fluid e.g. nitrogen, or some other non-flammable fluid. Alternatively, the propellant for deploying the sprinkler may be a non-flammable gas, and the propellant for motivating the suppressant may be compressed air. In this way, oxygen-containing air does not need to be supplied to a potential fire e.g. either before or after the suppressant during a suppression event.

The system may comprise a system controller and a pressure sensor, the system controller being configured to use the pressure sensor to detect a drop in pressure in a sprinkler supply pipe indicative of activation of a sprinkler, and to discharge the suppressant in response to the drop in pressure. The controller may be operable to open a valve (e.g. between a propellant source and the suppressant source) in response to the drop in pressure, thereby supplying propellant to the sprinkler. Once the sprinkler is activated (e.g. by a sprinkler bulb thereof breaking) the pressure in the sprinkler supply pipe will be released and the pressure in the supply pipe will drop. The controller may therefore detect that drop in pressure and determine that a fire has caused the sprinkler to be activated. As a consequence, the controller may discharge suppressant. The system may comprise valves as needed to control release of the propellant and/or suppressant, and each valve may be controlled by the controller.

The controller may be configured to open a valve between the (first) propellant source and the sprinkler supply pipe to pressurise the sprinkler supply pipe during a detection event. The controller may be configured to open that valve in response to a signal from a sensor. The controller may be configured to use the pressure sensor to detect an increase in pressure in the sprinkler supply pipe e.g. during a detection event, prior to a suppression event. The controller may therefore be configured to confirm that pressure in the supply pipe has increased to an expected level following a detection event, and thereby confirm that the supply pipe is pressurised and that the sprinkler is deployed.

The system may comprise a stabilisation valve operable to equalise pressure inside and outside of the system. The stabilisation valve may be arranged to provide fluid communication between the sprinkler supply pipe and the atmosphere external to the system. The stabilisation valve may be operable by the system controller, and the controller may be arranged to open the stabilisation valve prior to resetting the system.

The system may comprise a pressure sensor for checking that ambient pressure is reached when the stabilisation valve is opened. The pressure sensor may be controlled by the controller. The pressure sensor may be the same pressure sensor used by the controller for detecting a pressure increase in the supply pipe and for detecting a pressure decrease in the supply pipe e.g. a suppression event.

The system may comprise a sensor (e.g. a smoke detector, a heat detector or the like) so that the system can operate without the initial deployment of the sprinkler with propellant, and therefore the system can operate in the same manner as known systems, so that safety is not compromised. For example, following a detection event, if the sensor detects a fire using the sensor (as opposed to e.g. the pressure sensor on the supply pipe), the controller may discharge suppressant.

The controller may be arranged to supply suppressant to the sprinkler in the event that it does not detect an increase in pressure in the supply pipe after the first propellant source is opened. That is, the controller may be configured use suppressant to deploy the sprinkler in the event that the initial propellant supply fails to pressurise the supply pipe and hence fails to deploy the sprinkler. Thus, the system may be failsafe and may operate according to the principles of known systems (e.g. the same as the system of <FIG>).

The system may comprise a plurality of deployable sprinklers, each arranged as recited herein. The plurality of deployable sprinklers may be deployed by propellant from the (first) propellant source during a detection event, and may receive suppressant from the suppressant source during a suppression event. The system may comprise a plurality of propellant sources. The system may comprise multiple sprinklers for each propellant source. The system may comprise a plurality of suppressant sources.

According to a second aspect of the invention there is provided a method of using a deployable sprinkler fire suppression system comprising a deployable sprinkler, a suppressant source for supplying suppressant to the sprinkler during a suppression event, a propellant source for supplying propellant to the sprinkler to deploy the sprinkler, and a supply pipe arranged to supply suppressant to the sprinkler during the suppression event; the method comprising supplying propellant from the propellant source to pressurise the supply pipe to thereby deploy the sprinkler prior to supplying suppressant from the suppressant source for discharge during a suppression event.

The method may comprise deploying the sprinkler without using suppressant. The method may comprise using compressed gas to deploy the sprinkler. The method may comprise deploying the sprinkler in response to a signal from a sensor (e.g. a smoke detector, a heat detector, or the like).

The method may comprise reducing pressure within the sprinkler supply pipe to actuate the sprinkler from its deployed configuration. The method may comprise reducing pressure within the sprinkler supply pipe to a level less than ambient pressure outside the system, to thereby retract the deployed sprinkler. The method may comprise increasing pressure within the sprinkler supply pipe to thereby actuate the sprinkler to its deployed configuration, and decreasing pressure within the supply pipe to thereby actuate the sprinkler to its undeployed configuration. The method may comprise using a vacuum pump or other suitable mechanism to decrease pressure in the sprinkler supply pipe.

The method may comprise recharging the propellant. The method may comprise using a compressor to recharge the propellant, wherein the compressor is a component of the system. The method may comprise providing a system controller configured to control the compressor and thereby recharge the propellant.

The propellant may be compressed air. The method may comprise supplying compressed air to the propellant source to recharge the propellant source using the compressor. The method may therefore allow the system to be simply reset after a detection event and/or after a suppression event, as described above.

The method may comprise using propellant to supply suppressant the sprinkler during a suppression event, and may comprise providing the propellant for the suppressant in a dedicated source, separate from the propellant source for deploying the sprinkler.

The method may comprise discharging suppressant in response to a pressure drop in the supply pipe to the sprinkler. The method may comprise using a pressure sensor to monitor pressure in the sprinkler supply pipe. The method may comprise using the pressure sensor to confirm that the supply pipe has been pressurised during a detection event, and thereby confirming that the sprinkler has been deployed. The method may comprise using suppressant to deploy the sprinkler if (and only if) the pressure in the supply pipe does not reach a predetermined level during a detection event after the initial propellant has been supplied to the supply pipe (or e.g. after the controller has attempted to supply propellant to the supply pipe to deploy the sprinkler). The method may therefore comprise enacting a failsafe protocol in the event that the initial pressuring process (and hence sprinkler deployment) is unsuccessful.

The method may comprise equalising pressure inside and outside the system. The method may comprise monitoring pressure in the sprinkler supply pipe to confirm that pressure has been equalised. The method may comprise using a stabilisation valve to equalise pressure within the sprinkler supply pipe with pressure outside the fire suppression system.

The method may comprise checking that the system is ready for a suppression event by deploying the sprinklers. The method may therefore comprise testing the fire suppression system e.g. by performing a fire safety drill. The method may comprise using the controller to deploy the sprinkler, confirming that the sprinkler has been deployed, and then using the controller to retract the sprinkler. The method may subsequently comprise using the controller to recharge the propellant after the test.

The method may comprise using a deployable sprinkler fire suppression system as described herein with reference to the first aspect of the invention.

Certain preferred embodiments of the invention are described below by way of example only and with reference to the drawings in which:.

<FIG> shows a deployable sprinkler fire extinguishing system <NUM> in a first configuration. The system <NUM> comprises a plurality of deployable sprinklers <NUM>, a suppressant source <NUM> containing a suppressant (e.g. water), and a propellant source <NUM> containing a propellant (e.g. compressed nitrogen).

A valve <NUM> is disposed in a pipe connecting the propellant source <NUM> and the suppressant source <NUM>, and is arranged to control fluid communication therebetween. A system controller <NUM> is connected to the valve <NUM> and is configured to control its operation. Sensors <NUM> are connected to the controller <NUM> and are operable to inform the controller <NUM> of a detection event (i.e. a possible suppression event). Upon notification from a sensor <NUM>, the controller <NUM> opens the valve <NUM> so that the suppressant from the suppressant source <NUM> is supplied under pressure into a supply line <NUM> for supplying the sprinklers <NUM>.

Pressure within the supply line <NUM> therefore increases during a detection event, which in turn causes the sprinklers <NUM> to deploy. <FIG> shows the system of <FIG> during a detection event. The sprinklers <NUM> have been deployed because of increased pressure in the supply line <NUM> caused by opening of the valve <NUM>. Such deployable sprinklers <NUM> are often known as "pop-out" sprinklers because they "pop-out" into their deployed configuration e.g. from a ceiling. Once deployed, the sprinklers <NUM> may detect a fire (e.g. by rupture of a constituent sprinkler bulb) so that the suppressant in the charged supply line <NUM> can be released thereby. Release of suppressant from a sprinkler is therefore a suppression event, and is distinguished from a detection event in which the system initially detects a possible fire and deploys the sprinklers (but does not necessarily discharge suppressant).

The system of <FIG> is operable to prime itself to discharge suppressant whenever a sensor <NUM> notifies the controller <NUM> that it has detected a possible fire, and the system <NUM> of <FIG> is therefore in a ready state to discharge suppressant. However, the sensors <NUM> (e.g. smoke detectors, heat detectors, or the like) may not be able to distinguish between a genuine alarm, and a false alarm. That is, a given detection event (deployment of the sprinklers) does not necessarily mean that there will be a suppression event (discharge of suppressant from the sprinklers). Given the safety critical nature of system, it must be calibrated for caution and therefore errs towards sensitivity.

In the event of a false alarm, the sprinklers <NUM> are deployed by supplying suppressant to them in order to pressurise the supply line <NUM>. However, the system <NUM> must then be reset. A drain <NUM> is provided to depressurise the supply line <NUM>, after which the sprinklers <NUM> may be reset to their undeployed configuration, which is done manually. Further, an amount of suppressant and propellant will have been used and therefore the suppressant source <NUM> and propellant source <NUM> must also be manually recharged. Thus, false alarms are time and labour intensive.

<FIG> shows a deployable sprinkler fire suppression system <NUM> comprising a plurality of deployable sprinklers <NUM>, a suppressant source <NUM>, and a sprinkler supply pipe <NUM> arranged to supply suppressant from the suppressant source <NUM> to the sprinklers <NUM>. The system <NUM> further comprises a first propellant source <NUM> and a second propellant source <NUM>, as well as a system controller <NUM> arranged and configured to control a plurality of valves <NUM>, <NUM>, <NUM>, <NUM> in order to operate the system <NUM> based on information from sensors <NUM> and pressure sensor <NUM>.

The system <NUM> also comprises a vacuum pump <NUM> operable to reset the sprinklers <NUM> after a detection event by decreasing pressure within the supply pipe <NUM>, and a compressor <NUM> operable to recharge the first and second propellant sources <NUM> and <NUM>. A stabilisation valve <NUM> is also provided to allow fluid communication between the supply pipe <NUM> and the external atmosphere. The operation of the deployable sprinkler fire suppression system <NUM> and its various components will be described below with reference to <FIG>.

<FIG> shows the system of <FIG> during a detection event, during which the sensor <NUM> detects an event which could be indicative of a fire (e.g. smoke, heat, etc.). The controller <NUM> receives a corresponding signal from the sensor <NUM> and in response opens valve <NUM> so that propellant (e.g. compressed air) from the first propellant source <NUM> charges and pressurises the supply pipe <NUM>. The pressure within the supply pipe <NUM> therefore increases and hence causes the sprinklers <NUM> to deploy. The controller <NUM> can monitor the operation via the pressure sensor <NUM> to ensure that pressure in the supply pipe <NUM> reaches a predetermined level necessary to deploy the sprinklers <NUM>. The first propellant source <NUM> is sized relative to the supply pipe <NUM> to ensure that suitable pressure is reached e.g. approximately <NUM> bar (<NUM> MPa). The sprinklers <NUM> are therefore actuated during the detection event and thereby positioned to allow then to detect a fire. The system <NUM> is therefore ready to discharge suppressant in the event of a fire.

<FIG> shows the system <NUM> during a suppression event. The deployed sprinklers <NUM> are exposed and therefore can detect a fire. A sprinkler bulb in the sprinkler breaks when exposed to the fire, thereby opening the supply pipe <NUM> at that sprinkler <NUM>. The pressure in the supply pipe <NUM> drops, which drop is detected by the controller <NUM> via the pressure sensor <NUM>. In response to the pressure drop, the controller <NUM> opens the valve <NUM> so that suppressant is discharged from the suppressant source <NUM> by propellant from the second propellant source <NUM>. The suppressant then suppresses the fire.

<FIG> shows the system <NUM> being reset e.g. after a false alarm. The controller opens valves <NUM> and <NUM> and activates the vacuum pump <NUM> to decrease pressure in the supply pipe <NUM>. The pressure within the supply pipe <NUM> therefore drops to below ambient external pressure of the system <NUM>, and the sprinklers <NUM> are therefore retracted into their undeployed positions. The controller <NUM> can monitor the process using the pressure sensor <NUM> and confirm that the pressure in the supply pipe <NUM> decreases as expected.

<FIG> then shows the compressor <NUM> being activated by the controller <NUM> to recharge the first and/or second propellant sources <NUM> and <NUM> with compressed air. The stabilisation valve <NUM> is also opened after the sprinklers <NUM> have been retracted in order to balance pressure inside the supply pipe <NUM> with pressure outside the system <NUM>. The controller <NUM> can again use the pressure sensor <NUM> to ensure that ambient pressure is reached within the supply pipe <NUM>, and therefore ensure that a subsequent supply of propellant will cause the pressure to increase as required to deploy the sprinklers <NUM>.

Therefore, after a false alarm, the system <NUM> can be reset much more easily than the system of <FIG> because the propellant can be recharged directly using the compressor <NUM> and the sprinklers <NUM> can be reset to their undeployed configurations automatically and without manual input. Moreover, the system <NUM> does not use suppressant in order to deploy the sprinklers <NUM>, so it is not necessary to recharge the suppressant source <NUM> after a false alarm.

<FIG> shows how various components of the system <NUM> are not needed for operation. Thus, safety of the system <NUM> is not compromised relative to the known system <NUM> of <FIG>. The system of <FIG> can therefore operate in the same way as the system of <FIG>.

For example, if the controller <NUM> is notified of a detection event by the sensor <NUM> and opens the valve <NUM>, but does not detect a corresponding increase in pressure via the pressure sensor <NUM>, the controller <NUM> might conclude that there is a fault with the first propellant source <NUM>. The controller <NUM> can then open the valve <NUM> and deploy the sprinklers <NUM> using suppressant from the suppressant source <NUM>, similarly to the system of <FIG>. Thereafter, the system <NUM> will operate according to the same principles as the system <NUM> of <FIG> in the event that the initial deployment of the sprinklers <NUM> using only propellant fails.

Claim 1:
A deployable sprinkler fire suppression system comprising:
a deployable sprinkler (<NUM>), arranged to be deployed prior to a suppression event;
a suppressant source (<NUM>) arranged to discharge suppressant from the sprinkler (<NUM>) during the suppression event;
a propellant source (<NUM>) arranged to supply propellant to the sprinkler (<NUM>) to deploy the sprinkler (<NUM>) prior to the suppression event; and
a supply pipe (<NUM>) arranged to supply suppressant to the sprinkler (<NUM>) during the suppression event;
wherein the system is arranged to deploy the sprinkler (<NUM>) by pressurising the supply pipe (<NUM>) by supplying propellant from the propellant source (<NUM>) to the sprinkler (<NUM>) prior to supplying suppressant from the suppressant source (<NUM>).