GB2519385A - Water deluge system treatment apparatus and method - Google Patents

Abstract

The invention provides a method and apparatus for treating a deluge system. The apparatus 110 comprises a Venturi device comprising a first inlet 114 and an outlet 116 for connection to a flow path between a firemain 105 and an arrangement of deluge pipework 102. The Venturi device, which may be an eductor or inductor, comprises a second inlet 118 for connection to a source of corrosion inhibitor 124. A corrosion inhibitor control valve 122 is movable between an open condition in which corrosion inhibitor is drawn into the deluge pipework by motive fluid in the flow path, and a closed position in which the deluge pipework is isolated from the source of corrosion inhibitor. The corrosion inhibitor control valve may be hydraulically operable or may comprise a ball valve. In a first embodiment (figure 2), the apparatus forms part of a permanent or semi-permanent installation, for example, on an industrial facility such as an offshore hydrocarbon exploration and production installation. An alternative embodiment (figure 3) may be implemented as a portable or mobile apparatus removably coupled to an existing deluge system.

Description

1 Water Deluge System Treatment Apparatus and Method 3 The present invention relates to water deluge systems, and in particular to a method and 4 apparatus for treating water deluge systems. The invention has particular application to water deluge systems in offshore installations or vessels such as those used in the 6 hydrocarbon exploration and production industry.

8 Background to the invention

Conventional fire sprinkler systems are used widely in factories and commercial 11 properties, and increasingly in homes, as an active fire protection measure. A 12 conventional sprinkler system typically includes a network of sprinkler outlets located 13 overhead a protected area, connected to a water supply. The sprinkler outlets are 14 maintained in a closed position until activated. Activation is usually by way of a heat-sensitive element within one or more sprinklers, which react to an ambient temperature 1 exceeding an activation temperature. Above the activation temperature, the sprinklers are 2 opened and water flows from the water supply on to the protected area.

4 A water deluge system is designed to extinguish a fire by dispensing a large volume of S water over a large hazard area, and is typically used in industrial applications. Figure 1 is 6 a schematic view of a typical water deluge system according to the prior art. The water 7 deluge system, generally depicted at 10, consists of a dry side 12 and a wet side 13, 8 separated by a deluge valve 11. The dry side 12 has a network of pipes 16 and nozzles 9 17 which are maintained in an open condition. The dry side 12 contains air at atmospheric pressure. The wet side 13 of the deluge system is connected to a firemain 14 or other 11 supply at a water pressure significantly higher than atmospheric pressure.

13 The system, generally depicted at 10, is activated automatically by a fire alarm system 18 14 which controls the deluge valve 11. When the deluge valve is opened, water enters the pipe work on the dry side 12 of the deluge system and is dispensed over the hazard area 16 via the open nozzles 17. The deluge valve 11 stays open until it is activated to close.

18 Deluge systems find particular application in industrial applications, and are standard in 19 onshore and offshore installations used in the oil and gas exploration and production industry. Water deluge systems perform essential health and safety functions in oil and 21 gas installations, and therefore must be properly maintained by keeping the deluge 22 nozzles and associated pipe work clear of debris, corrosion and blockages to ensure that 23 the system will work effectively when required. A poorly maintained deluge system may 24 be unable to dispense sufficient volume of water to extinguish a fire which may of course lead to risks to life and cause damage to the assets. Many offshore water deluge systems, 26 particularly those on platforms and installations built before the 1990's, are believed to 27 include one or more of internal corrosion, corrosion deposits and/or marine growth, any of 28 which may restrict water flow in the pipe work and/or block nozzles.

A typical testing regime for deluge systems for the offshore oil and gas industry includes a 31 so-called wet test' performed regularly to meet the criteria of health and safety industry 32 regulators. A wet test involves activating the deluge system in a test period (for example 33 30 minutes) and checking the deluge system for blocked or restricted nozzles. This may 34 involve manual inspection of nozzles by operators wearing offshore survival suits, checking that flow through nozzles is as expected. One method involves placing a number 1 of receptacles beneath specific areas of the deluge system to collect dispensed seawater.

2 The receptacles have known opening sizes, and the volume of water collected may be 3 compared with the expected volume for the appropriate size of opening of the receptacle.

S Depending on the health and safety policies which apply, a deluge system deemed to be 6 in good condition may only need to be wet tested relatively infrequently (for example every 7 one to two years). However, where a deluge system has a history of problems or poor test 8 results, a health and safety regulatory body may require regular cleaning and/or wet 9 testing of the deluge system, for example every three months. This increases the inconvenience to the operator of the facility, the expense of running the facility, and the 11 risk to personnel and the integrity of the facility. Furthermore, frequent wet testing is likely 12 to exacerbate problems in the deluge system, for example by increasing corrosion of the 13 pipe work.

It is known to use pump systems to introduce chemicals into a deluge system and/or 16 firemain during a wet-test procedure, and to circulate chemicals through a deluge system 17 during a period of time at which the system is taken offline.

19 It has also been proposed to use venturi-effect inductors or eductors to introduce foam into a deluge system during its use in a fire-fighting operation. In such applications, the 21 inductor is configured inline between a deluge control valve and the deluge pipework. A 22 source of fire-fighting foam (such as Aqueous Film Forming Foams or AFFFs) is coupled 23 to the input side of the inductor, and when it is active, flow in the deluge pipework draws 24 the foam into the pipework for distribution to the facility via the deluge nozzles.

26 It amongst the aims and objects of the invention in at least one of its aspects to provide a 27 method and apparatus for treating a deluge system which addresses one or more of the 28 drawbacks associated with conventional deluge systems. A further aim of the invention is 29 to provide a method and apparatus which avoids or mitigates the problems associated with the performance of wet tests on deluge systems. An additional aim of the invention is to 31 provide a method and/or apparatus which is applicable to the treatment of deluge systems 32 in the offshore and/or oil and gas exploration and production industries. Further aims and 33 objects of the invention will become apparent from reading the following description.

1 Summary of the invention

3 According to a first aspect of the invention there is provided an apparatus for treating a 4 deluge system, the apparatus comprising: S a venturi device comprising a first inlet and an outlet for connection to a flow path between 6 a firemain and an arrangement of deluge pipework, the venturi device further comprising a 7 second inlet for connection to a source of corrosion inhibitor; 8 wherein the apparatus comprises a corrosion inhibitor control valve actuable between an 9 open condition in which corrosion inhibitor is drawn into the deluge pipework by motive fluid in the flow path, and a closed position in which the deluge pipework is isolated from 11 the source of corrosion inhibitor.

13 The venturi device may comprise an eductor or inductor (the terms "eductor" and 14 inductor" are used interchangeably in this specification). The second inlet may comprise an adjustable orifice, and may comprise a removable retaining ring housing a replaceable 16 orifice plate. The adjustable orifice may be configurable according to deluge system flow 17 rate and/or firemain pressure.

19 The corrosion inhibitor control valve may comprise a ball valve, and/or may be hydraulically operable. The corrosion inhibitor control valve may be manually operable.

21 Alternatively, or in addition, the corrosion inhibitor control valve may be operable in 22 response to a control signal from a control module.

24 The deluge system may comprise a deluge system control valve, which may be manually operable. Alternatively, or in addition, the deluge system control valve may be operable in 26 response to a control signal from a control module.

28 The apparatus may be operable to open the corrosion inhibitor control valve a 29 predetermined time before closure of the deluge system control valve. The apparatus may be operable to open the corrosion inhibitor control valve a predetermined time before a 31 scheduled closure time of the deluge system control valve. Alternatively, the apparatus 32 may be operable to delay closure of the deluge system control valve for a predetermined 33 time-interval after opening of the deluge system control valve corrosion inhibitor control 34 valve.

1 The venturi device of the apparatus may be located in line between a deluge system 2 control valve and the deluge pipework.

4 Preferably, the apparatus is configured to be removably coupled to the firemain hydrant S and/or the deluge pipework. More preferably, the apparatus is a part of a portable and/or 6 mobile unit 8 The venturi device of the apparatus may be located in a flow path disposed between the 9 firemain and the deluge pipework in parallel with the deluge system control valve. The apparatus may be connected to the firemain and or the deluge system pipework by one or 11 more quick connectors or instantaneous connectors. The apparatus may therefore be 12 removably connected into the deluge system.

14 The apparatus may therefore be coupled to the firemain and/or the deluge pipework in a particular location and used in a treatment operation, for example a scheduled treatment 16 operation for a section of the deluge system. The apparatus may subsequently be 17 decoupled from the firemain and/or the deluge pipework and redeployed to a second 18 location, where it is coupled to the firemain and/or the deluge pipework in a second 19 location and used to treat a different section of the deluge system. Alternatively or in addition, the apparatus may be decoupled from the firemain and/or the deluge pipework 21 and stored until it is required for a later treatment operation.

23 The apparatus may comprise a first conduit configured to be connected to a firemain, most 24 preferably a firemain hydrant. The first conduit may join the firemain to the first inlet of the venturi device. The first conduit may be connected to the venturi device by a quick 26 connector or an instantaneous connector.

28 The apparatus may comprise a second conduit configured to be connected to the deluge 29 pipework. The second conduit may join the outlet of the venturi device to the deluge pipework. The second conduit may be connected to the deluge pipework by a quick 31 connector or an instantaneous connector.

33 The apparatus may comprise a system inlet flow orifice, positioned in line with the venturi 34 device and upstream of the deluge pipework. The system inlet flow orifice may be 1 adjustable, and may be configurable according to deluge system flow rate and/or firemain 2 pressure. The system inlet flow orifice may be disposed in a flange connector.

4 The apparatus may comprise a check valve disposed between the second inlet of the S venturi device and the source of corrosion inhibitor, which may prevent flow from the 6 venturi device to the source of corrosion inhibitor.

8 The apparatus may comprise a control module operable to control the actuation of the 9 corrosion inhibitor control valve and/or the deluge system control valve.

11 According to a second aspect of the invention there is provided a deluge system 12 comprising: 13 an arrangement of deluge pipework coupled to a firemain via a deluge system control 14 valve; a venturi device disposed in a flow path between the firemain and the deluge pipework; 16 a source of corrosion inhibitor; and 17 a corrosion inhibitor control valve; 18 wherein the corrosion inhibitor control valve is actuable between an open condition in 19 which corrosion inhibitor is drawn into the deluge pipework by a motive fluid flowing in the flow path, and a closed position in which the deluge pipework is isolated from the source of 21 corrosion inhibitor.

23 Embodiments of the second aspect of the invention may include one or more features of 24 the first aspect of the invention or its embodiments, or vice versa.

26 According to a third aspect of the invention there is provided a method of treating a deluge 27 system comprising an arrangement of deluge pipework coupled to a fireriiain via a deluge 28 control valve, the method comprising: 29 providing an apparatus comprising: a venturi device disposed in a flow path between the firemain and the deluge pipework; a source of corrosion inhibitor; and 31 a corrosion inhibitor control valve; 32 actuating the corrosion inhibitor control valve to an open condition in which corrosion 33 inhibitor is drawn into the deluge pipework by a motive fluid flowing in the flow path.

1 The method preferably comprises actuating the corrosion inhibitor control valve to a closed 2 position in which the deluge pipework is isolated from the source of corrosion inhibitor.

4 Optionally, the method may comprise actuating the corrosion inhibitor control valve to an S open position during operation of the deluge system (i.e. when water flows through the 6 deluge pipework). The method may comprise opening a deluge control valve; opening the 7 corrosion inhibitor control valve; and closing the deluge system control valve.

9 The operation of the deluge system may comprise performing a wet test of the deluge system. The wet test may comprise activating the deluge system to cause liquid to flow 11 through from a firemain through the deluge system for a predetermined time.

13 Alternatively, the operation of the deluge system may be in response to a detected or 14 perceived fire-fighting condition.

16 The method may comprise opening the corrosion inhibitor control valve a predetermined 17 time before closure of the deluge system control valve. The method may comprise 18 opening the corrosion inhibitor control valve a predetermined time before a scheduled 19 closure time of the deluge system control valve. Alternatively, the method may comprise delaying closure of the deluge system control valve for a predetermined time-interval after 21 opening of the deluge system control valve corrosion inhibitor control valve.

23 The method may comprise closing the corrosion inhibitor control valve after closing the 24 deluge system control valve.

26 The predetermined time interval may be less than 5 minutes, and preferably is less than 27 two minutes. The predetermined time interval may be 1 minute or less, and may be 28 around 30 seconds.

The method may comprise connecting the apparatus to the deluge system. The method 31 may comprise mobilising the apparatus to a first deluge system location and connecting 32 the apparatus to the deluge system. The method may comprise disconnecting the 33 apparatus from a first deluge system location, moving the apparatus to a second deluge 34 system location, and connecting the apparatus to the deluge system at the second location.

2 The method may comprise configuring at least one flow orifice in the apparatus, which 3 may comprise configuring at least one flow orifice according to at least one of a deluge 4 system flow rate or a firemain pressure. The method may comprise fitting a removable S orifice plate in the apparatus.

7 Preferably, the method comprises configuring a flow orifice in a venturi device of the 8 apparatus. The flow orifice in the venturi device may comprise a metering orifice for the 9 venturi device, which may be connected to a second inlet of the venturi device.

11 The method may comprise configuring a flow orifice in a system inlet, positioned in line 12 with the venturi device and upstream of the deluge pipework.

14 Embodiments of the third aspect of the invention may include one or more features of the first or second aspects of the invention or its embodiments, or vice versa.

17 According to a fourth aspect of the invention there is provided an apparatus for treating a 18 deluge system, the apparatus comprising: 19 a venturi device comprising a first inlet conflgured to be connected to a firemain hydrant; an outlet configured to be connected to an arrangement of deluge pipework; and a second 21 inlet for connection to a source of corrosion inhibitor; 22 wherein the apparatus further comprises a corrosion inhibitor control valve actuable 23 between an open condition in which corrosion inhibitor is drawn into the deluge pipework 24 by motive fluid in the flow path, and a closed position in which the deluge pipework is isolated from the source of corrosion inhibitor.

27 Preferably, the apparatus is configured to be removably coupled to the firemain hydrant 28 and/or the deluge pipework. More preferably, the apparatus is a part of a portable and/or 29 mobile unit 31 The apparatus may therefore be coupled to the firemain and/or the deluge pipework in a 32 particular location and used in a treatment operation, for example a scheduled treatment 33 operation for a section of the deluge system. The apparatus may subsequently be 34 decoupled from the firemain and/or the deluge pipework and redeployed to a second location, where it is coupled to the firemain and/or the deluge pipework in a second 1 location and used to treat a different section of the deluge system. Alternatively or in 2 addition, the apparatus may be decoupled from the firemain and/or the deluge pipework 3 and stored until it is required for a later treatment operation.

S Embodiments of the fourth aspect of the invention may include one or more features of the 6 first to third aspects of the invention or its embodiments, or vice versa.

8 According to a further aspect of the invention, there is provided an apparatus substantially 9 described as herein with reference to Figure 2.

11 According to a further aspect of the invention, there is provided an apparatus substantially 12 as described herein with reference to Figure 3.

14 According to a further aspect of the invention, there is provided a method substantially as described herein with reference to Figures 2 to 4.

17 Brief description of the drawings

19 There will now be described, by way of example only, various embodiments of the invention with reference to the drawings, of which: 22 Figure 1 is a schematic view of a deluge system according to a the prior art; 24 Figure 2 is a schematic view of an apparatus and deluge system according to a first embodiment of the invention; 27 Figure 3 is a schematic view of an apparatus and deluge system according to a second 28 embodiment of the invention; and Figures 4A and 4B are flow diagrams depicting methods according to an embodiment of 31 the invention.

1 Detailed description of preferred embodiments

3 As noted above, Figure 1 is a schematic view of a conventional deluge system and is 4 useful for understanding the invention.

S

6 Referring now to Figure 2, there is shown schematically a deluge system 100, in which 7 apparatus according to a first embodiment of the invention is installed. The deluge 8 system 100 comprises a network of deluge pipework 102 located on the dry side of the 9 deluge control valve 104. The deluge valve 104 connects the dry side to a firemain 105.

The pipes 102 are filled with air at atmospheric pressure. The pipes 102 comprise a 11 number of deluge nozzles 106 distributed throughout the pipework 102. Nozzles 106 are 12 open so that when the deluge system 100 is activated by opening the deluge control valve 13 104 water rapidly fills the pipes 102 and discharges through the nozzles.

The apparatus, generally shown at 110, comprises a venturi device in the form of an 16 eductor. The eductor is located downstream of the deluge control valve 104 and is 17 positioned in line in a flow path between the firemain 105 and the deluge pipe work 102.

19 In this embodiment, the selected eductor is a flanged in-line proportioner, which comprises a first inlet 114 and an outlet 116 for a motive fluid, an internal venturi nozzle (not shown), 21 and a second inlet 118 for an educed fluid. An example of the suitable eductor is the 3- 22 inch (76.2mm) flanged in-line foam proportioner available from Ansul Incorporated of 23 Wisconsin, USA.

The first inlet 114 couples the eductor to the outlet line from the deluge control panel 104, 26 and the outlet 116 is coupled to the deluge pipe work. Fluid flowing from the deluge 27 control valve 104 and into the deluge pipe work 102 is the motive fluid for the eductor.

28 The second inlet 118 is connected to conduit 120 via a check valve 122. The conduit 120 29 leads to a source of corrosion inhibitor in the form of reservoir 124. The reservoir 124 has a capacity selected to provide corrosion inhibitor volumes sufficient to treat the deluge 31 system on which the apparatus is installed.

33 The conduit 120 is connected to an outlet 126 on the reservoir via a corrosion inhibitor 34 control valve 128. A check valve 122 prevents the passage of the water out of the inlet 118 and into the conduit 120. In this embodiment, the conduit 120 is a rigid suction hose, 1 and the corrosion inhibitor control valve 128 is a controllably actuable ball valve. It will be 2 appreciated that in alternative embodiments of the invention, other forms of conduit and 3 corrosion inhibitor control valve may be used.

S The eductor 112 also comprises an adjustable metering orifice, which defines the flow path 6 between the second inlet and the body of the eductor. A removable retaining ring 119 7 allows the metering orifice to be replaced, enabling the selection of orifice size according 8 to the deluge system flow rate.

In some embodiments of the invention, the apparatus 110 is installed into multiple 11 arrangements of deluge pipe work via a crossover. The condition of the crossover is 12 adjusted to select which of the deluge systems is to be treated. In this configuration, the 13 reservoir 124 is selected to have a capacity to contain enough corrosion inhibitor for the 14 treatment of the largest of the arrangements of deluge pipe work to be treated by the apparatus.

17 An example method of use for the apparatus 110 will now be described.

19 When the deluge control valve 104 is closed, the deluge pipe work 102 is full of air at atmospheric pressure, and the firemain 105 is full of pressurised water. Corrosion inhibitor 21 control valve 128 is closed. When the deluge valve 104 is opened, water discharges from 22 the firemain 105 to the arrangement of deluge pipe work 102, via the eductor 112. While 23 fluid flows to the deluge pipework, valve 128 is opened to fluidly connect the inlet 118 with 24 the reservoir 124. The relatively low pressure created by the venturi device causes corrosion inhibitor to be drawn into the eductor 112, and into the flow stream which passes 26 into the deluge pipe work.

28 The corrosion inhibitor control valve 128 allows an operator to have control over the 29 distribution of corrosion inhibitor into the system 100. For example, during a wet test, which may last several minutes, it may be undesirable to distribute corrosion inhibitor 31 through the deluge pipe work throughout the duration of the test. Instead, the most 32 effective use of corrosion inhibitor may be to only dose the deluge water at the end of the 33 wet test, for example during the last minute or 30 seconds before the deluge valve 104 is 34 closed. This reduces wastage of corrosion inhibitor, facilitates dosing of the deluge water 1 with corrosion inhibitor at the end of the test, and means that no untreated sea water is 2 allowed to pass through the deluge system, which may tend to cause additional corrosion.

4 As well as operation during a wet-test as described above, it will be apparent that the S corrosion inhibitor control valve can also be actuated to enable dosing of the deluge water 6 during a genuine activation of the deluge system for a fire fighting application, or 7 alternatively during a spurious activation of the deluge system. In either case, it is 8 desirable for the corrosion inhibitor control valve to be opened at the end of the operation 9 of the deluge system, enabling dosing of the deluge water immediately prior to closure of the deluge control valve 104.

12 The embodiment described with reference to Figure 2 is particularly suitable for permanent 13 or semi-permanent installation in a deluge system, for example a deluge system which 14 forms a part of fire protection structure on an industrial facility such as an offshore hydrocarbon exploration and production installation.

17 Figure 3 shows schematically an alternative embodiment of the invention which is 18 implemented as a portable or mobile apparatus which is removably coupled into a deluge 19 system. This embodiment also has particularly application to deluge systems which forms a part of fire protection structure on an industrial facility such as an offshore hydrocarbon 21 exploration and production installation, but has the advantage of being readily mobilised 22 coupled into the system when required, for example as part of scheduled treatment at the 23 end of deluge system wet-tests or subsequent to a genuine or spurious activation of the 24 deluge system.

26 The apparatus, generally shown at 210, is connected to a deluge system 200, which 27 consists of an arrangement of deluge pipework 202 on a downstream side of a deluge 28 control valve 204 from a firemain 205. The apparatus 210 is connected to the deluge 29 system 200 by a mechanical T-piece 208 disposed downstream of the deluge control valve 204. The apparatus is also connected to the firemain 205 via a firemain hydrant 209 via 31 the outlet connection of a hydrant shut-off valve 211. Conduits 230 and 232 are linked to 32 first inlet 214 and an outlet 216 of a venturi device which again is in the form of eductor 33 212. The eductor 212 is the same as eductor 112, and includes an adjustable metering 34 orifice which defines the flow path between the second inlet and the body of the eductor.

1 A removable retaining ring 219 allows the metering orifice to be replaced, enabling the 2 selection of orifice size according to the deluge system flow rate.

4 Conduit 220 connects a second inlet 218 of the eductor 212 to a source of corrosion S inhibitor in the form of reservoir 224. The reservoir 224 has a capacity selected to provide 6 corrosion inhibitor volumes sufficient to treat the deluge system on which the apparatus is 7 installed. A ball valve 229 is provided between the reservoir 224 and the eductor 212.

9 The eductor 212 together with the conduits 230 and 232 form a bypass conduit between the tie-in point 209 at the firemain 205 and the mechanical T-piece 208 on the dry side of 11 the deluge system 200.

13 In this embodiment, the selected eductor 112 is again a flanged in-line proportioner.

14 However, in this embodiment the eductor 112 is coupled to conduits 230, 232 via instantaneous couplings 236 such as those used in fire hose systems. Instantaneous 16 couplings 236 are also used to join the conduits 230 and 232 to the firemain hydrant shut- 17 off valve 211 and the dry side of the deluge system 202. In the latter case, the connection 18 is achieved via a flange 238 and a corrosion inhibitor control valve 228. The flange 238 19 comprises an adjustable metering orifice, which defines the flow path between the eductor 212 and the deluge pipework 202. The orifice is set according to the operating firemain 21 pressure to regulate the overall flow through the apparatus 210.

23 In this embodiment, the control valve 228 is a controllably actuable ball valve similar to the 24 ball valve 128 of the apparatus 110. However, the ball valve 228 is automatically controlled via a control module 250, which also controls the deluge system control valve 26 204 as will be described below.

28 In an alternative embodiment of the invention, an instantaneous coupling 236 is disposed 29 between the control valve 228 and the mechanical T-piece 208. This enables the apparatus 212, including the valve 228, to be disconnected from the deluge system and 31 redeployed in another location. A blind flange (not shown) can then be attached to the 32 mechanical T-piece in order to close off the deluge pipework. It will be appreciated that in 33 further alternative embodiments a coupling may be positioned at a selection of different 34 locations between the various components of the apparatus. The valve 228 or flange 238 may be a pad of a portable unit of the apparatus or may be permanently or semi- 1 permanently installed on the deluge system. Alternatively the valve 228 and or flange 238 2 may be removed from the deluge pipework 202 as a separate step, prior to blanking off the 3 mechanical T-piece with a blind flange or similar.

S An example method of use for the apparatus 210 will now be described.

7 When the deluge control valve 204 is closed, the deluge pipe work 102 is full of air at 8 atmospheric pressure, and the firemain 205 is full of pressurised water. Valve 211 is 9 open, and conduits 230 and 232 are at the operating pressure of the firemain 205. Fluid does not flow in the apparatus 210, as deluge valve 204 and control valve 228 are closed.

11 Valve 229 is open, and check valve 222 prevents fluid from flowing into the reservoir 224.

13 When the deluge valve 204 is opened, water discharges from the firemain 205 to the 14 arrangement of deluge pipe work 202. Wiile fluid flows to the deluge pipework, valve 228 is opened to fluidly connect the conduit 232 with the deluge pipework 202, causing fluid to 16 flow through the apparatus from the firemain hydrant 209 to the 1-piece 208. As fluid 17 flows through the apparatus 210, the relatively low pressure created by the venturi device 18 causes corrosion inhibitor to be drawn into the eductor 212, and creating a mix of water 19 and corrosion inhibitor in the conduit 232. The water and corrosion inhibitor mixture enters the deluge system through the flange 238 and valve 228, and passes into the deluge 21 pipework 202 to exit through nozzles 206.

23 When the deluge valve 204 is closed, fluid continues to pass through the apparatus 210 24 and into the deluge pipework (at lower flow rate) until the valve 228 is closed. Closing the valve 228 after closure of the deluge valve mitigates against the flow of untreated water 26 into the deluge system 200. After valve 228 is closed, a rich mix (relatively high 27 concentration) of corrosion inhibitor is formed in the relatively small volume of the conduit 28 232 until the flow through the apparatus 210 ceases.

As noted above, it is desirable to only dose the deluge water at the end of the operation of 31 the deluge system, for example during the last minute or 30 seconds before the deluge 32 valve 204 is closed. This reduces wastage of corrosion inhibitor, facilitates dosing of the 33 deluge water with corrosion inhibitor at the end of the test, and means that no untreated 34 sea water is allowed to pass through the deluge system, which may tend to cause 1 additional corrosion. The automatic control of the valve 228 via the control module 250 2 facilitates effective operation of the system.

4 In one mode of operation, shown schematically as 260 in Figure 4A, the control module 250 receives a signal to end the deluge operation at step 261, whether it is the end of a 6 wet-test or the resetting of the deluge system in a fire-fighting application. Before 7 actuating the deluge valve 204 to close, the control module 250 sends a signal to open the 8 corrosion inhibitor control valve 228 (step 262) to allow dosing of the deluge water with 9 corrosion inhibitor. After a pre-determined delay, for example 30 seconds, the deluge valve 204 is closed (step 263) by the control module, and the corrosion inhibitor control 11 valve 228 is subsequently closed (step 264). In this embodiment, the actuation of the 12 valve 228 is in-built into the control system and is fully automated with the ending or 13 resetting of the deluge operation.

It will be appreciated that similar sequence can be performed in a partially or fully manual 16 operation, as shown generally at 270 in Figure 48. When it is required to end or reset the 17 deluge system (step 271), opening of the valve 228 (step 272), closing the deluge valve 18 204 (step 273), and closing the valve 228 (step 274) may be sequentially performed by an 19 operator. Optionally, one or more of the steps may be linked via a common control: for example, a control system may automatically close the valve 228 after the deluge control 21 valve 204 has been manually closed.

23 It will be appreciated that the methods and sequences of valve operation described with 24 reference to Figures 4A and 48 are also applicable to operation of the apparatus of Figure 2.

27 The invention provides a method and apparatus for treating a deluge system. The 28 apparatus comprises a venturi device comprising a first inlet and an outlet for connection 29 to a flow path between a firemain and an arrangement of deluge pipework. The venturi device, which may be an eductor or inductor, comprises a second inlet for connection to a 31 source of corrosion inhibitor. A corrosion inhibitor control valve actuable between an open 32 condition in which corrosion inhibitor is drawn into the deluge pipework by motive fluid in 33 the flow path, and a closed position in which the deluge pipework is isolated from the 34 source of corrosion inhibitor.

1 The invention in at least one of its aspects provides a method and apparatus for treating a 2 deluge system which addresses one or more of the drawbacks associated with 3 conventional deluge systems, and in particular which mitigate the problems associated 4 with the performance of wet tests on deluge systems. The invention is particularly S applicable to the treatment of deluge systems in the offshore and/or oil and gas exploration 6 and production industries.

8 Various modifications to the above-described embodiments may be made within the scope 9 of the invention, and the invention extends to combinations of features other than those expressly claimed herein.