DESC:DESCRIPTION
TECHNICAL FIELD
The present invention generally relates to fire suppressant systems for oil tanks, and more particularly, to the fire suppressant system for a fixed cone roof tank.
BACKGROUND
Foam is widely used for fire prevention and suppression in oil installations across the world. Stable foam extinguishes a flammable or combustible liquid fire by spreading over the hydrocarbon source surface and simultaneously cooling, separating the ignition source from the hydrocarbon surface, suppressing vapors, and separating the liquid hydrocarbon from air or oxygen. When introduced with the appropriate pressure, water mixed with air in a foam chamber provides an effective fire suppressing foam.
To provide immediate foam-based fire suppression to a flammable liquid in a fixed cone roof tank, devices called foam chambers are often employed at such storage sites. Figure 1 illustrates a side view of fire suppressant system 100 attached to a fixed cone roof tank 102 containing flammable liquid 104 as known in the art. Referring to Figure 1, the fire suppressant system 100 comprises a foam chamber 106 and an inline foam inductor 108 having foam supply conduit 110. The inline foam inductor 108 allows combination of water and foaming substance in appropriate proportions to form fire suppressant foam (3% of foam concentrate and 97% water). As would be understood, the inline foam inductor 108 facilitates foam solution to long distance from injection point to the foam chamber 106. The inline foam inductor 108 is calibrated for a given fixed flow/pressure relation. Typically, the pressure is maintained at 7 Kg/cm2. The inline foam inductor 108 is kept outside dyke wall and foam solution is piped from outside hazard area.
The foam chamber 106 is in a cylindrical or annular shape and is typically positioned above the flammable liquid 104. The foam chamber 106 receives the fire suppressant foam from the inline foam inductor 108 through the foam supply conduit 110. The foam chamber 106 aerates and expands the fire suppressant foam to form aerated fire suppressant foam 112 and supplies the aerated fire suppressant foam 112 to the fixed cone roof tank 102. For the sake of brevity, only one foam chamber has been illustrated. Generally, a plurality of foam chambers is positioned at equal interval surrounding the fixed cone roof tank 102.
Figure 2 illustrates a schematic of the foam chamber 106 attached to the fixed cone roof tank 102, as known in the art. The foam chamber 106 includes an inlet conduit 200 having a flanged inlet end 202. The flanged inlet end 202 is attached to flanged outlet end 204 of the foam supply conduit 110 to receive the fire suppressant foam. An orifice plate 206 is installed between the flanged inlet end 202 and the flanged outlet end 204 to control a flow rate of the fire suppressant foam. An expansion conduit 208 is attached to the inlet conduit 200. The expansion conduit 208 has an internal diameter larger than an internal diameter of the inlet conduit 200 and is concentrically attached to the inlet conduit 200 such that an inlet end of the expansion conduit 208 is attached to an outlet end of the inlet conduit 200. The expansion conduit 208 aerates and expands the fire suppressant foam received through the inlet conduit 200. An outlet end 210 of the expansion conduit 208 is sealed using a glass vapour seal 210. The glass vapour seal 210 prevents ingress of vapours from the fixed cone roof tank 102 into the foam chamber 106. The expansion conduit 208 is enclosed in an expansion enclosure 214. The expansion enclosure 214 has a flanged outlet end 216 attached to a flanged inlet end 218 of a discharge conduit 200.
During operation, the glass vapour seal 210 is broken by pressure of the aerated and expanded fire suppressant foam to enter the expansion enclosure 214. A minimum pressure in the range of 3.0 Kg/cm2 to 3.5 Kg/cm2 is required to break the glass vapour seal 210. The aerated fire suppressant foam travels through the expansion enclosure 214 and enters the discharge conduit 220. The discharge conduit 220 directs the aerated and expanded fire suppressant foam to an interior of the fixed cone roof tank 102 where a deflector (not shown in the figure) directs the aerated and expanded fire suppressant foam such that the aerated and expanded fire suppressant foam flows down an inside wall of the fixed cone roof tank 102.
In some fire suppressant or extinguishing system, other types of breakable seals are used. By way of example, US Patent Publication US1774165A describes a mixing box for foam fire extinguishing system. The mixing box includes foam making materials and is secured to an oil tank in position to discharge into the foam. The mixing box also includes a rupturable diaphragm arranged to exclude tank vapors. Tensile strength of the rupturable diaphragm is less than pressure of foam to be delivered. During operation, the rupturable diaphragm is broken by pressure of the foam to enter the tank.
However, in these fire suppressant systems, the glass vapour seal or the diaphragm breaks with pressure of foam and is therefore required to be replaced after each operation or testing of fire suppressant systems. This makes the whole process cumbersome and costly, especially during routine and periodic testing. In addition, an operational risk is always involved during the period in which the glass vapour seal or the diaphragm is being replaced. Further, during testing, the foam chamber has to be rotated or disconnected from the storage tank. This makes the whole process cumbersome, labor-intensive, and time-consuming.
There are solutions that overcome this deficiency. By way of example, US Patent Publication US4838356A describes a multiple remote testing system of a foam extinguishing system for oil fixed cone roof tanks. Compressed gas, pneumatically operated three-way valve, foam collector & sealing cap are integral part of said system. Sealing cap is provided with plurality of guide bars extending downward into first supply line and is connected to a ring shaped connecting rod to suppress any swing which may be generated by vertical motion of said cap. However, this system is very complex as pneumatic control systems are required to control the valve. In addition, manufacturing and maintenance cost is also very high.
By way of another example, US Patent Publication US9027661B2 describes a foam chamber having a closable testing outlet. The foam chamber can operate in a testing mode and an operation mode. An inlet conduit accepts a fire suppressant fluid and is attached to an expansion conduit. An expansion enclosure having two closable outlets is also attached to the inlet conduit and surrounds the expansion conduit. One outlet empties into the expansion enclosure. The other outlet extends through the wall of the expansion enclosure and empties outside of the expansion enclosure. Both of the closable outlets can be fitted with either an unbreakable seal or a frangible seal. If the foam chamber is configured for normal operation, the unbreakable seal is placed on the outlet that extends through the wall of the expansion enclosure and a frangible seal is placed on the outlet that empties into the expansion enclosure. However, in this system also a breakable seal. In addition, placement of the seals has to be changed according to operation mode or testing mode. Further, existing foam chambers have to be replaced with the new foam chamber since the expansion conduit has two outlets. This process is again cumbersome and costly.
In another example solution, high back-pressure foam makers (HBPFM) with check valve are designed to generate expanded foam for the purpose of subsurface foam injection into a cone-roof liquid hydrocarbon storage tank. The HBPFM is typically located outside the diked area surrounding the storage tank. Expanded foam is injected through a dedicated foam line or into a product line to the storage tank. However, very high pressure in the range of 10 Kg/cm2 to 20 Kg/cm2 is required at an inlet of the HBPFM such that the foam injection can overcome tank-head pressure and viscosity characteristics of the storage tank. Further, discharge velocity of foam from the HBPFM is very low and thereby limits surface turbulence and fuel entertainment which causes deteriorating foam blanket. Further, the subsurface foam injection is limited up-to two point discharge only and is not recommended for polar solvent with high water miscibility and as such application of HBPFM is limited and cannot be used with existing foam chambers.
Hence, there is a need for a solution that overcomes the above-mentioned deficiencies.
SUMMARY
This summary is provided to introduce a selection of concepts in a simplified format that are further described in the detailed description of the present disclosure. This summary is not intended to identify key or essential inventive concepts of the claimed subject matter, nor is it intended for determining the scope of the claimed subject matter. In accordance with the purposes of the disclosure, the present disclosure as embodied and broadly described herein describes a fire suppressant system for a fixed cone roof tank.
In accordance with one embodiment of the present disclosure, the fire suppressant system comprises a foam chamber and a discharge conduit. The foam chamber comprises an inlet conduit having a flanged inlet end and an open outlet end. The flanged inlet end is attached to foam supply conduit of an inline foam inductor to receive, expand, and aerate fire suppressant foam. The foam chamber comprises an expansion conduit having an open inlet end and an open outlet end. The open inlet end is attached to the open outlet end of the inlet conduit for expanding the fire suppressant foam. The foam chamber further comprises an expansion enclosure having a flanged outlet end and surrounding the expansion conduit such that the open outlet end of the expansion conduit is in fluid communication with the expansion enclosure. The discharge conduit comprises a flanged inlet end attached to the flanged outlet end of the expansion enclosure for discharging the fire suppressant foam into the fixed cone roof tank. The fire suppressant system further comprises a wafer type swing check valve installed between the flanged outlet end of the expansion enclosure and the flanged inlet end of the discharge conduit.
In accordance with another embodiment of the present enclosure, the fire suppressant system comprises an inlet conduit having a flanged inlet end and an open outlet end. The flanged inlet end is attached to foam supply conduit of an inline foam inductor to receive, expand, and aerate fire suppressant foam. The fire suppressant system comprises an expansion conduit having an open inlet end and a flanged outlet end. The open inlet end is attached to the open outlet end of the inlet conduit for expanding the fire suppressant foam. The fire suppressant system further comprises a discharge conduit. The discharge conduit comprises a flanged inlet end attached to the flanged outlet end of the expansion conduit for discharging the fire suppressant foam into the fixed cone roof tank. The fire suppressant system further comprises a wafer type swing check valve installed between the flanged outlet end of the expansion conduit and the flanged inlet end of the discharge conduit.
In the embodiments, the wafer type swing check valve is in a normally closed position prior to the fire suppressant foam being discharged through the flanged outlet end of the expansion enclosure The wafer type swing check valve is having an operating pressure range from 0.75 Kg/cm2 to 1.5 Kg/cm2.
Further, in the embodiments, the discharge conduit includes a first flanged outlet for attaching to the fixed cone roof tank and a second flanged outlet for attaching to a test outlet conduit. The second flanged outlet is positioned in positioned in proximity to the flanged inlet end. Each of the first flanged outlet and the second flanged outlet comprises a butterfly valve to control a flow of the fire suppressant foam being discharged from the discharge conduit.
As such, the fire suppressant system is configured to operate in one of an operating mode and a testing mode. In the operating mode, the butterfly valve at the second flanged outlet is in a fully closed position and the butterfly valve at the first flanged outlet is in a fully open position to control the flow of the fire suppressant foam being discharged into the fixed cone roof tank. In the testing mode, the butterfly valve at the first flanged outlet is in a fully closed position and the butterfly valve at the second flanged outlet is in a fully open position to control the flow of the fire suppressant foam being discharged into the test outlet conduit.
The advantages of the present invention include, but not limited to eliminating the use of glass vapour seal or diaphragm by use of the wafer type swing check valve and thereby the need for replacing the vapour seal in a vapour seal box or foam chamber is eliminated. The wafer type swing check valve is in normally close position and has a minimum operating pressure range. As such, the pressure requirement for directing the fire suppressant foam from the inline foam inductor to the foam chamber has reduced considerably.
Further, the use of butterfly valves in the discharge conduit enables the testing of the fire suppressant system without having to rotate the fire suppressant system and without discharging foam inside the tank.
Further, complex pneumatic control systems are not required to control the wafer type swing check valve and therefore costs of manufacturing and maintaining the fire suppressant system are reduced. In addition, overall maintenance of the fire suppressant system is easy. In addition, the wafer type swing check valve can be fitted retrospectively to the existing fire suppressant systems.
These aspects and advantages will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims.
BRIEF DESCRIPTION OF FIGURES
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Figure 1 illustrates a side view of a fire suppressant system attached to a fixed cone roof tank, as known in the art.
Figure 2 illustrates a schematic of a foam chamber for the fire suppressant system attached to the fixed cone roof tank, as known in the art.
Figure 3 illustrates a schematic of a fire suppressant system for a fixed cone roof tank, in accordance with one embodiment of the present disclosure.
Figure 4 illustrates a side-cut view of a foam chamber for the fire suppressant system, in accordance with one embodiment of the present disclosure.
Figure 5 illustrates a schematic of a fire suppressant system attached to the fixed cone roof tank, in accordance with another embodiment of the present disclosure.
Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have been necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present invention. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
DETAILED DESCRIPTION
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skilled in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.
Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings.
Figure 3 illustrates a schematic of a fire suppressant system 300 for a fixed cone roof tank 302 containing flammable liquid, in accordance with one embodiment of the present disclosure. Figure 4 illustrates a side-cut view of the fire suppressant system 300, in accordance of the present disclosure. Referring to Figure 3 and Figure 4, the fire suppressant system 300 comprises a foam chamber 304 and an inline foam inductor 306 having a foam supply conduit 308. The foam chamber 304 is in a cylindrical or annular shape and is typically positioned above the flammable liquid. The foam chamber 302 is attached to the inline foam inductor 306 through the foam supply conduit 308. The inline foam inductor 306 allows combination of water and foaming substance in appropriate proportions to form fire suppressant foam. The foam chamber 304 receives the fire suppressant foam through the foam supply conduit 308. The foam chamber 304 aerates and expands the fire suppressant foam to form aerated fire suppressant foam and supplies the aerated fire suppressant foam to the fixed cone roof tank 302. For the sake of brevity, only one fire suppressant system has been illustrated. Generally, a plurality of fire suppressant systems is positioned at equal interval surrounding the fixed cone roof tank 302. As such, each of the fire suppressant system 300 may be controlled individually from a remote site as known in the art.
The foam chamber 304 comprises an inlet conduit 310 having a flanged inlet end 400 and an open outlet end 402. The flanged inlet end 400 is attached to a flanged opening 404 of the foam supply conduit 308. The inlet conduit 310 comprises an orifice plate 406 attached to the flanged inlet end 400 to control a flow of the fire suppressant foam from the foam supply conduit 308. The inlet conduit 310 further comprises an air opening 408 attached to an air supply conduit (not shown in the figure) to receive air (represented by an arrow) for aeration of the fire suppressant foam.
The foam chamber 304 further comprises an expansion conduit 312 having an open inlet end 410 and an open outlet end 412. The open inlet end 410 of the expansion conduit 312 is attached to the open outlet end 402 of the inlet conduit 310 for expanding the fire suppressant foam. The expansion conduit 312 is having an internal diameter greater than an internal diameter of the inlet conduit 310 and is concentrically attached to the outlet end 402 of the internal conduit 310.
The foam chamber 304 further comprises an expansion enclosure 314 having a flanged outlet end 414. The expansion enclosure 314 surrounds the expansion conduit 308 such that the open outlet end 412 of the expansion conduit 312 is in fluid communication with the expansion enclosure 314. The expansion enclosure 314 is having an internal diameter greater than the internal diameter of the expansion conduit 312 and is concentrically attached to the inlet end 402 of the expansion conduit 312. The expansion enclosure 314 also has a removable closure 416 and a device 418 for securing the removable closure 416.
The fire suppressant system 300 further comprises a discharge conduit 316 having a flanged inlet end 318. The flanged inlet end 318 is attached to the flanged outlet end 414 of the expansion enclosure 314 for discharging the fire suppressant foam into the fixed cone roof tank 302.
In accordance with the present enclosure, a wafer type swing check valve 320 is installed between the flanged outlet end 414 of the expansion enclosure 314 and the flanged inlet end 318 of the discharge conduit 316. The wafer type swing check valve 320 has no end connections. The wafer type swing check valve 320 prevents ingress of vapours from the fixed cone roof tank 302 into the foam chamber 304.
Further, the wafer type swing check valve 320 is having an operating pressure range from 0.75 Kg/cm2 to 1.5 Kg/cm2 and has low pressure drop. The wafer type swing check valve 320 is in a normally closed position prior to the fire suppressant foam being discharged through the flanged outlet end 414 of the expansion enclosure 314. As such, the wafer type swing check valve 320 is in a fully open position when pressure of the fire suppressant foam discharged through the flanged outlet end 414 of the expansion enclosure 314 is substantially equal to the operating pressure range of the wafer type swing check valve 320. The wafer type swing check valve 320 begins closing as flow of the fire suppressant foam from the expansion enclosure 314 decreases and returns to the normally closed position when the flow of the fire suppressant foam has completely ebbed.
In one implementation, the wafer type swing check valve 320 comprises a ductile iron body, stainless steel (SS) disc, and a nitrile rubber or EPDM rubber seat. The wafer type swing check valve 320 has a D-shaped high torsion spring coil that ensures quick valve closure. An eccentric disc shaft combination with the disc seat ensures a positive shut off return media once the flow of the fire suppressant foam has completely ebbed.
Further, the discharge conduit 316 is perpendicular to the inlet conduit 310, the expansion conduit 312, and the expansion enclosure 314. The discharge conduit 316 includes a first flanged outlet 322 and a second flanged outlet 324. The second flanged outlet 324 is positioned in positioned in proximity to the flanged inlet end 414 of the discharge conduit 316. The first flanged outlet 322 is attached to the fixed cone roof tank 102 and the second flanged outlet 324 is attached to a test outlet conduit 326. The test outlet conduit 326 is perpendicular to the discharge conduit 316 and is parallel to the inlet conduit 310, the expansion conduit 312, and the expansion enclosure 314. In one implementation, the first flanged outlet 322 is attached on side wall of the fixed cone roof tank 102 such that the fire suppressant foam flows down along inside of the side wall of the fixed cone roof tank 102. As such, in such implementation, the discharge conduit 316 can be linear conduit, as shown in the figure. In another implementation, the first flanged outlet 322 is attached on roof of the fixed cone roof tank 102 such that the fire suppressant foam flows directly on the flammable liquid. This enables the fire suppressant foam to cover a wider surface area of the flammable liquid within the fixed cone roof tank 502. In addition, the flammable liquid can be filled to higher level within the fixed cone roof tank 502. As such, in such implementation, the discharge conduit 316 can be a bent conduit.
Further, each of the first flanged outlet 322 and the second flanged outlet 324 comprises a butterfly valve (328-1, 328-2) to control a flow of the fire suppressant foam being discharged from the discharge conduit 316. The butterfly valve (328-1, 328-2) at each of the first flanged outlet and the second flanged outlet is installed in one of a vertical position and a horizontal position.
In accordance with the present disclosure, the fire suppressant system 300 is configured to operate in one of an operating mode and a testing mode. As such, the fire suppressant system 300 is operated from a remote site. Consequently, the fire suppressant foam is supplied from the inline foam inductor 306 to the inline conduit 310. As the wafer type swing check valve 320 is having the operating pressure range from 0.75 Kg/cm2 to 1.5 Kg/cm2, an initial pressure of the fire suppressant foam is less than 7 Kg/cm2. The expansion conduit 312 then expands and aerates the fire suppressant foam while reducing pressure of the fire suppressant foam, which then enters the expansion enclosure 314 through the open outlet end 414. The expansion enclosure 314 further expands the fire suppressant foam and reduces velocity and pressure of final expanded fire suppressant foam between 0.75 Kg/cm2 to 1.5 Kg/cm2. The final expanded fire suppressant foam moves the wafer type swing check valve 320 to a fully open position and enters the discharge conduit 316.
During the operating mode, the butterfly valve 328-2 at the second flanged outlet 324 is in a fully closed position and the butterfly valve 328-1 at the first flanged outlet 322 is in a fully open position to control the flow of the fire suppressant foam being discharged into the fixed cone roof tank 302.
During the testing mode, the butterfly valve 328-1 at the first flanged outlet 322 is in a fully closed position and the butterfly valve 328-2 at the second flanged outlet 324 is in a fully open position to control the flow of the fire suppressant foam being discharged into the test outlet conduit 326. For the sake of brevity, the figure 3 illustrates the testing mode of operation.
Figure 5 illustrates a schematic of a fire suppressant system 500 attached to a fixed cone roof tank 502, in accordance with another embodiment of the present disclosure. The fire suppressant system 500 comprises an inline foam inductor 504 having a foam supply conduit 506. The inline foam inductor 504 allows combination of water and foaming substance in appropriate proportions to form fire suppressant foam.
The fire suppressant system 500 comprises an inlet conduit 508 having a flanged inlet end 510 and an open outlet end 512. The flanged inlet end 510 is attached to a flanged opening 516 of the foam supply conduit 506 to receive the fire suppressant foam from the inline foam inductor 504. The inlet conduit 508 comprises an orifice plate 514 attached to the flanged inlet end 510 to control a flow of the fire suppressant foam from the foam supply conduit 506. The inlet conduit 508 further comprises an air opening (not shown in the figure) attached to an air supply conduit (not shown in the figure) to receive air (represented by an arrow) for aeration of the fire suppressant foam.
The fire suppressant system 500 further comprises an expansion conduit 518 having an open inlet end 520 and a flanged outlet end 522. The open inlet end 520 of the expansion conduit 518 is attached to the open outlet end 512 of the inlet conduit 508 for expanding the fire suppressant foam. The expansion conduit 518 is having an internal diameter greater than an internal diameter of the inlet conduit 508 and is concentrically attached to the open outlet end 512 of the internal conduit 508. In one implementation, the expansion conduit 518 can be a bent conduit as shown in the figure 5 for the sake of brevity. In other implementation, the expansion conduit 518 can be a linear conduit, as show in figure 3.
The fire suppressant system 500 further comprises a discharge conduit 524 having a flanged inlet end 526. The flanged inlet end 526 is attached to the flanged outlet end 522 of the expansion conduit 518 for discharging the fire suppressant foam into the fixed cone roof tank 502. For the sake of brevity, only one fire suppressant system has been illustrated. Generally, a plurality of fire suppressant systems is positioned at equal interval surrounding the fixed cone roof tank 502. As such, each of the fire suppressant system 500 may be controlled individually from a remote site as known in the art.
In accordance with the present enclosure, a wafer type swing check valve 528 is installed between the flanged outlet end 522 of the expansion conduit 518 and the flanged inlet end 526 of the discharge conduit 524. The wafer type swing check valve 528 has no end connections. The wafer type swing check valve 528 prevents ingress of vapours from the fixed cone roof tank 502 into the expansion conduit 518.
Further, as described earlier, the wafer type swing check valve 528 is having an operating pressure range from 0.75 Kg/cm2 to 1.5 Kg/cm2 and has low pressure drop. The wafer type swing check valve 528 is in a normally closed position prior to the fire suppressant foam being discharged through the flanged outlet end 522 of the expansion conduit 518. As such, the wafer type swing check valve 528 is in a fully open position when pressure of the fire suppressant foam discharged through the flanged outlet end 522 of the expansion conduit 518 is substantially equal to the operating pressure range of the wafer type swing check valve 528. The wafer type swing check valve 528 begins closing as flow of the fire suppressant foam from the expansion conduit 518 decreases and returns to the normally closed position when the flow of the fire suppressant foam has completely ebbed.
In one implementation, as described earlier, the wafer type swing check valve 528 comprises a ductile iron body, stainless steel (SS) disc, and a nitrile rubber or EPDM rubber seat. The wafer type swing check valve 528 has a D-shaped high torsion spring coil that ensures quick valve closure. An eccentric disc shaft combination with the disc seat ensures a positive shut off return media once the flow of the fire suppressant foam has completely ebbed.
Further, the discharge conduit 524 is perpendicular to the inlet conduit 508 and the expansion conduit 518. The discharge conduit 524 includes a first flanged outlet 530 and a second flanged outlet 532. The second flanged outlet 532 is positioned in positioned in proximity to the flanged inlet end 526 of the discharge conduit 524. The first flanged outlet 530 is attached to the fixed cone roof tank 102 and the second flanged outlet 532 is attached to a test outlet conduit 534. The test outlet conduit 534 is perpendicular to the discharge conduit 524 and is parallel to the inlet conduit 508 and the expansion conduit 518. In one implementation, the first flanged outlet 530 is attached on side wall of the fixed cone roof tank 502 such that the fire suppressant foam flows down along inside of the side wall of the fixed cone roof tank 102. As such, in such implementation, the discharge conduit 524 can be linear conduit, as shown in the figure. In another implementation, the first flanged outlet 530 is attached on roof of the fixed cone roof tank 502 such that the fire suppressant foam flows directly on the flammable liquid. This enables the fire suppressant foam to cover a wider surface area of the flammable liquid within the fixed cone roof tank 502. In addition, the flammable liquid can be filled to higher level within the fixed cone roof tank 502. As such, in such implementation, the discharge conduit 524 can be a bent conduit.
Further, each of the first flanged outlet 530 and the second flanged outlet 532 comprises a butterfly valve (536-1, 536-2) to control a flow of the fire suppressant foam being discharged from the discharge conduit 524. The butterfly valve (536-1, 536-2) at each of the first flanged outlet and the second flanged outlet is installed in one of a vertical position and a horizontal position.
In accordance with the present disclosure, the fire suppressant system 500 is configured to operate in one of an operating mode and a testing mode. As such, the fire suppressant system 500 is operated from a remote site. Consequently, the fire suppressant foam is supplied from the inline foam inductor 504 to the inline conduit 508. As the wafer type swing check valve 528 is having the operating pressure range from 0.75 Kg/cm2 to 1.5 Kg/cm2, an initial pressure of the fire suppressant foam is less than 7 Kg/cm2. The expansion conduit 518 then expands and aerates the fire suppressant foam while reducing pressure of the fire suppressant foam between 0.75 Kg/cm2 to 1.5 Kg/cm2. The final expanded fire suppressant foam moves the wafer type swing check valve 528 to a fully open position and enters the discharge conduit 524.
During the operating mode, the butterfly valve 536-2 at the second flanged outlet 532 is in a fully closed position and the butterfly valve 536-1 at the first flanged outlet 530 is in a fully open position to control the flow of the fire suppressant foam being discharged into the fixed cone roof tank 502.
During the testing mode, the butterfly valve 536-1 at the first flanged outlet 530 is in a fully closed position and the butterfly valve 536-2 at the second flanged outlet 532 is in a fully open position to control the flow of the fire suppressant foam being discharged into the test outlet conduit 534. For the sake of brevity, the figure 5 illustrates the testing mode of operation.
Experimental Results: An experiment was conducted to compare the operational efficiency of the fire suppressant system comprising the foam chamber 304 having the wafer type swing check valve 318 according to the present disclosure, namely foam chamber A, and a foam chamber having glass vapour seal, namely foam chamber B. In the experiment, both the foam chamber A and foam chamber B have an individual capacity of 300 liters per minute (lpm). The foam chamber A and foam chamber B are fixed on a fixed cone roof tank having a diameter of 12.96 meters (m) and height of 7.61 m. According to the Oil Industry Safety Directorate (OISD244), foam solution requirement is 5lpm per square meter of liquid/product surface area of the tank to be protected. As such, the foam solution requirement is 659.24 lpm for the tank having diameter of 12.96 m. In addition, two butterfly valves of diameter 3 inch and 4 inch, respectively, were fitted at the discharge conduit in accordance with the present disclosure in both the foam chamber A and foam chamber B. When a hydrant line delivered pressurized water to the inline inductor and foam is added at atmospheric pressure, foam solution is made. This solution was delivered to both the foam chamber A and foam chamber B. Both the foam chamber A and foam chamber B discharge satisfactory foam solution outside storage tanks. Similar experiment was conducted to compare the operational efficiency of the fire suppressant system 500 comprising the expansion conduit 518 having the wafer type swing check valve 528 according to the present disclosure, namely and the foam chamber having glass vapour seal, namely foam chamber B. Both the fire suppressant system 500 and foam chamber B discharge satisfactory foam solution outside storage tanks.
Thus, the present disclosure eliminates the use of glass vapour seal or diaphragm by use of the wafer type swing check valve (320, 528) and thereby the need for replacing the glass vapour seal in the foam chamber is eliminated. The wafer type swing check valve (320, 528) is in normally close position and has an operating pressure range from 0.75 Kg/cm2 to 1.5 Kg/cm2. Typically, foam chambers with glass vapour seal requires a minimum pressure of 3.5 Kg/cm2. As such, the pressure requirement for directing the fire suppressant foam from the inline foam inductor (306, 502) to the expansion conduit (312, 518) has reduced considerably due to the use of wafer type swing check valve (320, 528) with or without the foam chamber.
Further, the use of butterfly valves (328-1, 328-2; 536-1, 536-2) in the discharge conduit (316,530) enables the testing of fire suppressant system (300, 500) without having to rotate the fire suppressant system (300, 500) and without discharging foam inside the fixed cone roof tank 302.
Further, complex pneumatic control systems are not required to control the wafer type swing check valve (320, 528) and therefore costs of manufacturing and maintaining the fire suppressant system (300, 500) are reduced. In addition, overall maintenance of the fire suppressant system (300, 500) is easy. In addition, the wafer type swing check valve (320, 528) can be fitted retrospectively to the existing fire suppressant systems, such as for example the fire suppressant system 100 illustrated in figure 2, attached with inline foam conductors (306, 502).
While specific language has been used to describe the present disclosure, any limitations arising on account thereto, are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein. The drawings and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. Clearly, the present disclosure may be otherwise variously embodied, and practiced within the scope of the following claims.
,CLAIMS:WE CLAIM:
1. A fire suppressant system for a fixed cone roof tank, the fire suppressant system comprising:
a foam chamber comprising:
an inlet conduit having a flanged inlet end attached to foam supply conduit of an inline foam inductor to receive, expand, and aerate a fire suppressant foam, and an open outlet end;
an expansion conduit having an open inlet end attached to the open outlet end of the inlet conduit for expanding the fire suppressant foam and an open outlet end; and
an expansion enclosure having a flanged outlet end and surrounding the expansion conduit such that the open outlet end of the expansion conduit is in fluid communication with the expansion enclosure; and
a discharge conduit having a flanged inlet end attached to the flanged outlet end of the expansion enclosure for discharging the fire suppressant foam into the fixed cone roof tank, wherein a wafer type swing check valve is installed between the flanged outlet end of the expansion enclosure and the flanged inlet end of the discharge conduit.

2. The fire suppressant system as claimed in claim 1, wherein the wafer type swing check valve is having an operating pressure range from 0.75 Kg/cm2 to 1.5 Kg/cm2.

3. The fire suppressant system as claimed in claim 2, wherein the wafer type swing check valve is in a normally closed position prior to the fire suppressant foam being discharged through the flanged outlet end of the expansion enclosure.

4. The fire suppressant system as claimed in claim 1, wherein:
the discharge conduit includes a first flanged outlet for attaching to the fixed cone roof tank and a second flanged outlet for attaching to a test outlet conduit;
the second flanged outlet is positioned in positioned in proximity to the flanged inlet end; and
each of the first flanged outlet and the second flanged outlet comprises a butterfly valve to control a flow of the fire suppressant foam being discharged from the discharge conduit.

5. The fire suppressant system as claimed in claim 4, wherein the foam chamber is configured to operate in one of:
an operating mode, wherein the butterfly valve at the second flanged outlet is in a fully closed position and the butterfly valve at the first flanged outlet is in a fully open position to control the flow of the fire suppressant foam being discharged into the fixed cone roof tank; and
a testing mode, wherein the butterfly valve at the first flanged outlet is in a fully closed position and the butterfly valve at the second flanged outlet is in a fully open position to control the flow of the fire suppressant foam being discharged into the test outlet conduit.

6. The fire suppressant system as claimed in claim 4, wherein:
the discharge conduit is perpendicular to the inlet conduit, the expansion conduit, and the expansion enclosure;
the test outlet conduit is perpendicular to the discharge conduit and is parallel to the inlet conduit, the expansion conduit, and the expansion enclosure; and
the butterfly valve at each of the first flanged outlet and the second flanged outlet is installed in one of a vertical position and a horizontal position.

7. The fire suppressant system as claimed in claim 1, wherein:
the expansion conduit is having an internal diameter greater than an internal diameter of the inlet conduit and is concentrically attached to the outlet end of the internal conduit; and
the expansion enclosure is having an internal diameter greater than the internal diameter of the expansion conduit and is concentrically attached to the inlet end of the expansion conduit.

8. A fire suppressant system for a fixed cone roof tank, the fire suppressant system comprising:
an inlet conduit having a flanged inlet end attached to foam supply conduit of an inline foam inductor to receive, expand, and aerate a fire suppressant foam, and an open outlet end;
an expansion conduit having an open inlet end attached to the open outlet end of the inlet conduit for expanding the fire suppressant foam and a flanged outlet end; and
a discharge conduit having a flanged inlet end attached to the flanged outlet end of the expansion conduit for discharging the fire suppressant foam into the fixed cone roof tank, wherein a wafer type swing check valve is installed between the flanged outlet end of the expansion conduit and the flanged inlet end of the discharge conduit.

9. The fire suppressant system as claimed in claim 8, wherein the wafer type swing check valve is having an operating pressure range from 0.75 Kg/cm2 to 1.5 Kg/cm2.

10. The fire suppressant system as claimed in claim 9, wherein the wafer type swing check valve is in a normally closed position prior to the fire suppressant foam being discharged through the flanged outlet end of the expansion conduit.

11. The fire suppressant system as claimed in claim 8, wherein:
the discharge conduit includes a first flanged outlet for attaching to the fixed cone roof tank and a second flanged outlet for attaching to a test outlet conduit;
the second flanged outlet is positioned in positioned in proximity to the flanged inlet end; and
each of the first flanged outlet and the second flanged outlet comprises a butterfly valve to control a flow of the fire suppressant foam being discharged from the discharge conduit.

12. The fire suppressant system as claimed in claim 11, wherein the fire suppressant system is configured to operate in one of:
an operating mode, wherein the butterfly valve at the second flanged outlet is in a fully closed position and the butterfly valve at the first flanged outlet is in a fully open position to control the flow of the fire suppressant foam being discharged into the fixed cone roof tank; and
a testing mode, wherein the butterfly valve at the first flanged outlet is in a fully closed position and the butterfly valve at the second flanged outlet is in a fully open position to control the flow of the fire suppressant foam being discharged into the test outlet conduit.

13. The fire suppressant system as claimed in claim 11, wherein:
the discharge conduit is perpendicular to the inlet conduit, the expansion conduit, and the expansion enclosure;
the test outlet conduit is perpendicular to the discharge conduit and is parallel to the inlet conduit, the expansion conduit, and the expansion enclosure; and
the butterfly valve at each of the first flanged outlet and the second flanged outlet is installed in one of a vertical position and a horizontal position.