Patent Publication Number: US-2004046670-A1

Title: Gas blanket management system and method

Description:
FIELD OF THE DISCLOSURE  
       [0001] The present disclosure generally relates to a storage tank monitoring system and, more particularly, to a gas blanket monitoring system and method.  
       BACKGROUND OF THE DISCLOSURE  
       [0002] Storage tanks, and particularly large industrial storage tanks, are often used to store fluids. These fluids typically produce environmentally unfriendly emissions such as, for example, volatile organic compounds, hydrocarbons or other fugitive chemicals. Due to their unfriendly emissions, these fluids are often required to be isolated from the atmosphere. Atmospheric isolation is typically achieved by placing an inert gas, such as nitrogen, on top of the enclosed tank, thereby creating a gas barrier between the stored media fluid and the atmosphere. Such a gas blanket or gas blanketing system may be used for several reasons and situations including, but not limited to, eliminating or minimizing the amount of emissions produced by the stored media and protecting or isolating the stored media in the tank from the atmosphere to minimize or eliminate the contamination of the stored media.  
       [0003] Generally, storage tanks are not designed to withstand excessive pressure. Thus, the blanketing gas on top of the tank is usually held at a low pressure. To ensure the blanket gas is at a low or desired pressure, the blanket gas, as the fluid media is added to or removed from the tank, must also be added or removed to compensate for the removal or addition of volume occupied by the fluid media. To obtain a suitable pressure in the tank, a gas blanketing regulator may be utilized in conjunction with a vapor recovery device or other device able to release the gas pressure on the interior of the tank.  
       [0004] In addition to pressure regulators, other devices have been utilized to obtain various values and data regarding the status of the stored media and blanket gas within a storage tank. For example, in a case of an emergency, such as when the tank is experiencing excessive pressure, an emergency vent valve may be used. In another example, if a tank is experiencing an excessive, negative pressure situation which may cause a tank to implode, a vacuum or relief vent may be used. Tanks have also been equipped with level monitoring devices for obtaining data relating to the amount of stored media. Other tank monitoring devices may include a tank fill system, a tank extraction or outflow system, and a tank heating system.  
       [0005] The different above-mentioned technologies and devices have been used independently of each other, thereby providing specific data or accomplishing a single purpose for which the device was specifically intended. These separate devices, however, are limited in their utility and are unable to independently manage a storage tank system. The benefits of regulation based on combined/holistic data gathering includes lower gas blanketing costs by providing efficient product blanketing preventing product contamination, minimizing product evaporation, reducing blanketing gas losses, avoiding product spoilage or deterioration, and assuring compliance with clean air regulation. Therefore, there still remains a need for a gas blanket management system that combines gas blanketing controls with the monitoring of other tank parameters.  
       SUMMARY OF THE DISCLOSURE  
       [0006] In accordance with one aspect of the disclosure among others, a storage tank monitoring system is disclosed. In one exemplary embodiment, the system includes a controller unit, a blanket gas flow sensor, and one of a storage tank sensor and a blanket gas sensor. The stored media sensor is adapted to sense a stored media parameter from which a corresponding stored media signal is generated. The blanket gas sensor is adapted to sense a storage tank blanket gas parameter from which a corresponding blanket gas signal is generated. The blanket gas flow sensor is adapted to sense the a flow of blanket gas from which a corresponding blanket gas flow signal is generated. The controller unit is adapted to receive the blanket gas flow signal and one of the stored media signal and the blanket gas signal and, responsively, generate a blanket gas leak indicator signal.  
       [0007] In accordance with another aspect of the disclosure among others, a method of monitoring a storage tank is disclosed. In one exemplary embodiment, the method includes sensing a flow of blanket gas into a storage tank and generating a responsive blanket gas flow signal thereto. The method in one exemplary embodiment includes sensing at least one of a storage tank media parameter and a storage tank blanket gas parameter and generating one of a responsive stored media signal and blanket gas signal thereto. The method in one exemplary embodiment includes receiving the blanket gas flow signal and at least one of the stored media signal and the blanket gas signal as inputs and responsively generating a blanket gas leak indicator signal. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0008]FIG. 1 is a schematic diagram of a gas blanketing management system as constructed in accordance with the teachings of the disclosure;  
     [0009]FIG. 2 is a block diagram of the electronic components of a controller unit in the gas blanketing management system;  
     [0010]FIG. 3 is a block diagram of a gas blanketing management system network;  
     [0011]FIG. 4 is a schematic diagram of a gas blanketing management system network;  
     [0012]FIG. 5 is a schematic diagram of a package valve; and  
     [0013]FIG. 6 is a flowchart of an exemplary routine that may be performed during operation of the gas blanketing management system. 
    
    
     [0014] While the method and device described herein are susceptible to various modifications and alternative constructions, certain illustrative embodiments thereof have been shown in the drawings and will be described below in detail. It should be understood, however, that there is no intention to limit the invention to the specific forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined by the appended claims.  
     DETAILED DESCRIPTION  
     [0015] A gas blanketing management system  20  as described herein, may be used in a storage tank storing fluid media that produces environmentally unfriendly emissions such as, volatile organic compounds, hydrocarbons, or other fugitive chemicals. Due to its unfriendly emissions, the fluid media may be required to be isolated from the atmosphere. In one exemplary embodiment, such atmospheric isolation may be achieved by placing an inert gas or blanket gas such as nitrogen on top of the enclosed tank, thereby creating a gas barrier between the stored media fluid and the atmosphere.  
     [0016] Referring now to the drawings, and with specific reference to FIG. 1, the gas blanketing management system constructed in accordance with the teachings of the disclosure is generally depicted by reference numeral  20 . As shown therein, the gas blanketing management system  20  in one exemplary embodiment includes a blanket gas  22 , a stored media  24 , a storage tank  30 , at least one tank inlet  28 , at least one tank outlet  31 , at least one stored media sensor  32 , at least one blanket gas sensor  34 , a controller unit  36 , and at least one control output device  37 .  
     [0017] In one exemplary embodiment, the storage tank  30 , may be a storage tank having various shapes and sizes that may be adapted to store and contain a variety of fluid media defined herein as fluid or gaseous materials. The stored media sensor  32  may be a sensor adapted to gauge one of several parameters of the stored media within the storage tank  30 . As shown in FIG. 2, in one exemplary embodiment, the stored media sensor  32  may be a stored media level sensor  38 , a stored media inflow sensor  39 , a stored media outflow sensor  40 , a stored media temperature sensor  41 , or any other desired parameter of the stored media in the tank  30 .  
     [0018] Those of ordinary skill in the art will readily recognize that the type of stored media sensor  32  and the manner in which the stored media sensor  32  gauges the different parameters may vary greatly. In one exemplary embodiment, the stored media sensor  32 , for example, may be a float valve. The float valve may include a float (not shown) which floats on top of the stored media thereby indicating tank level and, ultimately, the amount of stored media present in the storage tank  30 . In one alternative embodiment, the stored media sensor  32  may, however, be a pressure sensor located near the bottom of the storage tank  30 , also for attaining the amount of stored media present in the storage tank  30 .  
     [0019] Similarly, the blanket gas sensor  34  may be a sensor adapted to gauge one of several parameters of the blanket gas within the storage tank  30 . As also shown in FIG. 2, in one exemplary embodiment, the blanket gas sensor  34  may be a blanket gas pressure sensor  42 , a blanket gas inflow sensor  44 , a blanket gas outflow sensor  46 , a blanket gas temperature sensor  47 , or any other parameter desired of the blanket gas. Once again, those of ordinary skill in the art will readily recognize that the type of blanket gas sensor  34  and the manner in which the blanket gas sensor  34  gauges the different parameters may vary greatly. The blanket gas sensor  34  may be a pressure sensor located near the top of the storage tank  30 , thereby obtaining the pressure of the blanket gas  22  in the storage tank  30 . In another exemplary embodiment, the blanket gas sensor  34  may, however, be one or more flow sensors, wherein a single flow sensor may measure the amount of blanket gas  22  coming into or out of the storage tank  30 , or wherein a pair of flow sensors may measure the amount of blanket gas  22  coming into and out of the storage tank  30 .  
     [0020] The sensing of flow through the stored media inflow and outflow sensors  39 ,  40  and the blanket gas inflow and outflow sensors  44 ,  46  may also be accomplished in a variety of ways. As also shown in FIG. 2, flow may be determined by measuring the inlet pressure of the blanket gas  22  with a pressure sensor  44  such as a inlet pressure tap  48 , or the outlet pressure of the blanket gas with a pressure sensor such as a outlet pressure tap  50 , and measuring an orifice of a blanket gas regulator  64 . The size of the orifice may be obtained by measuring the travel distance of a valve plug or the like, via a travel sensor  52 , and providing information for mathematically determining the blanket gas flow rate.  
     [0021] The amount and type of stored media sensors  32  and blanket gas sensors  34 , or sensors in general are not, however, limited to two or to the type of sensors identified above. As such, in one exemplary embodiment, the blanket gas management system  20  may have one or more additional sensors able to measure various parameters of the fluid media  24  and/or the blanket gas  22 . For example, additional sensors may include, but are not limited to, temperature and/or heat tracing sensors. The storage tank  30  may, as indicated above, have one or more stored media temperature sensors  41  adapted to sense the temperature of the stored media  24 . In one exemplary embodiment, the storage tank  30  may include one or more gas blanket temperature sensors  47  adapted to sense the temperature of the blanket gas.  
     [0022] The controller unit  36 , which is adapted to receive the signals generated by the various sensors and transmit device signals in various forms. The controller unit  36  may, for example, include a transceiver able to receive and/or transmit signals via a wireless or wire technology. More specifically, the signals generated by the sensors may be transmitted to the controller unit  36  via a hardwire such as RS485 or telephone technology, or via wireless technology, such as RF radio or Cellular Digital Packet Data (CDPD), or the like. Similarly, the method of transmitting a signal from the controller unit  36 , may be accomplished via any of the above-mentioned or other ways readily recognized by those of ordinary skill in the art.  
     [0023] More specifically, as shown in the block diagrams of FIGS. 2 and 3, a number of components may be incorporated into the controller unit  36 . Referring to FIG. 2, the controller unit  36  in one exemplary embodiment may include a program memory  54 , a microcontroller or microprocessor (MP)  56 , a random-access memory (RAM)  58  and an input/output (VO) circuit  60 , all of which may be interconnected via an address/data bus  62 . It should be appreciated that although only one microprocessor  56  is shown, the controller unit  36  may include additional microprocessors. Similarly, the memory of the controller unit  36  may include multiple RAMs  58  and multiple program memories  54 . Although the I/O circuit  60  is shown as a single block, it should be appreciated that the I/O circuit  60  may include a number of different types of I/O circuits. The RAM(s)  58  and program memories  54  may be implemented, for example, as semiconductor memories, magnetically readable memories, and/or optically readable memories or other memories recognized by those of ordinary skill in the art.  
     [0024]FIG. 2 illustrates that sensors, including stored media sensors  32  and blanket gas sensors  34 , may be operatively coupled to the I/O circuit  60 . Each of the above components may be so coupled by a unidirectional or bidirectional, single-line or multiple-line data link, which may depend on the design of the component that is used.  
     [0025] Components may be connected to the I/O circuit  60  via a direct line or conductor. Different connection schemes could be used. For example, one or more of the components shown in FIG. 2 may be connected to the I/O circuit  60  via a common bus or other data link that is shared by a number of components. Furthermore, those of ordinary skill in the art will recognize that some of the components may be directly connected to the microprocessor  56  without passing through the I/O circuit  60 .  
     [0026] As shown in FIGS. 1, 2, and  4  the output of the controller unit  36  may be connected to one or more storage tank input devices  28 , one or more storage tank output devices  31 , and one or more controller output devices  37  adapted to receive and/or respond to a device signal generated by the controller unit  36 . The means by which the device signal is transmitted can, once again, vary greatly and may be similar or equal to the means by which the input signal was received.  
     [0027] More specifically, the storage tank input devices  28  may include, as indicated in FIG. 2, a stored media inflow valve or regulator  62  adapted to control flow of the stored media  22  into the tank  30 , a blanket gas valve or regulator (PAD valve)  64  to control flow of the blanket gas  22  into the tank  30 , as well as a vacuum relief valve  66  to allow for atmospheric pressure to be communicated into the tank  30  to avoid implosion or coupling of the tank  30 .  
     [0028] Similarly the storage tank output devices  31  may include a blanket gas outflow valve or regulator (DEPAD valve)  68  to control flow of the blanket gas  22  out of the tank  30 , a stored media outflow valve or regulator  70  to control flow of the stored media  24  out of the tank  30 , as well as a pressure relief valve  72  to vent excess pressure to the atmosphere to avoid damage or implosion of the tank  30 .  
     [0029] The gas pressure at which the gas blanketing management system  20  operates, may be any pressure suitable for its intended purpose. In one exemplary embodiment, the blanket gas line pressure coming into the gas blanketing management system  20  may be in the range of 20-200 PSI, and more specifically may be approximately 100 PSI. Similarly, the blanket gas pressure within the storage tank  30 , may be any pressure suitable for its intended purpose. In one exemplary embodiment, the blanket gas pressure within the storage tank  30  may be in the range of ¼ inch H 2 O (60° F.)- 20  PSI, and more specifically may be approximately 1-2 PSI. In this disclosure and appended claims, the term “PAD” refers to the blanketing of areas in the storage tank  30  with blanketing gas to maintain pressure, whereas the term “DEPAD” refers to the venting of areas in the storage tank  30 , containing blanketing gas, to limit the gas blanketing pressure.  
     [0030] The controller output devices  37  may include an alarm configured to activate upon receiving, or failing to receive, an indicator signal from the controller unit  36 . As such, in one exemplary embodiment, the tank controller output devices  37  may include, as shown in FIG. 2, a stored media alarm  74 , a blanket gas alarm  75 , a stored media sensor alarm  76 , or a blanket gas sensor alarm  77 . Such alarms may be audible, visual, or tactile in nature, or may be automated so as to cease operation or take other corrective action as needed.  
     [0031] The controller unit  36 , and the gas blanketing management system  20  in general, may also communicate with external devices. For example, the gas blanketing management system  20  and the controller unit  36  may be adapted to communicate with a third party, such as a company or entity responsible for the stored media  24 , a supplier of the blanket gas  22 , and/or various authorities such as a fire department, police and/or other entities. With the third party communication ability, the controller unit  36  may communicate the information obtained from the above-referenced sensors and/or the control devices directly or indirectly to the responsible or necessary people. The people responsible for the stored media  24 , for example, may be notified immediately if an alarm is activated, or may be kept up-to-date on the level of the stored media  24 . Similarly, the blanket gas supplier may be notified at the time the blanket gas supply reaches a level at which the supply of gas should be replenished. It may also be desired to communicatively link one or more of the sensors, control devices and/or alarms to one or more entities, such as the fire department, thereby in this example, providing a quick response ability to the department in case of an emergency with which the storage tank  30  is involved.  
     [0032] The gas blanketing management system  20  may, therefore, as seen in FIG. 3, include a first network  110 . The first network  110  may include at least one controller unit  36  operatively coupled to a network computer  112  via a network data link or bus  114 . The gas blanketing management system  20  may also include a second network  116 . The second network  116  includes at least one controller unit  118  operatively coupled to a network computer  120  via a network data link or bus  122 . The first and second networks  110 ,  116  may be operatively coupled to each other via a network  124 , which may comprise, for example, the Internet, a wide area network (WAN), or local area network (LAN), via a first and second network links  126  and  128 .  
     [0033] As indicated in FIG. 4, the controller units  36  of the first network  110  may be provided in a first tank farm at location A, and the second network  116  of controller units  118  may be provided in a second tank farm located in a separate geographic location from the first tank farm, such as at location B. For example, the two tank farms may be located in different areas of the same city, or they maybe located in different states, countries or other geographical locations. The network  124  may include a plurality of network computers or server computers (not shown), each of which may be operatively interconnected.  
     [0034] The network computer  112  may be a server computer. The network computer  112  may be used to collect and analyze data relating to operating the controller units  36 . For example, the network computer  112  may continuously receive data from each of the controller units  36  indicative of sensor and/or control device status from each of the storage tanks  30 . Similarly, the network computer  120  may be a server computer and may be used to perform the same or different functions as the network computer  112  in relation to the controller unit  118  described above.  
     [0035] The communications that occur between the above mentioned network  110  or networks  110 ,  116 , the controller unit  36 , the stored media sensors  32  or the blanket gas sensors  34  need not be limited to sensor signals received from the stored media sensors  32  or to device signals transmitted to the stored media input/output devices  62 ,  70  (stored media signals), or to sensor signals received from the blanket gas sensors  34  or to device signals transmitted to the blanket gas input/output devices  64 ,  68  (blanket gas signals). For example, the communications may include information that is specific to the storage tank  30 , the blanket gas  22 , and/or the stored media  24 , that may be communicated separately from the stored media signals or the blanket gas signals, or may be communicated along with the stored media signals or blanket gas signals by encoding or uniquely tagging the respective signals with the storage tank, the blanket gas, and/or the stored media information.  
     [0036] For example, the stored media level sensor  38  may communicate a sensor signal to the controller unit  36  and/or a network  110 , indicating an amount of stored media  24 . Additionally, that sensor signal in one exemplary embodiment may include a tag or may be encoded with information relating to the storage tank  30  from which the stored media level sensor  38  is sensing. In particular, this information may include, but is not limited to, a unique storage tank specific tag for identifying the storage tank  30 , or a unique stored media specific tag for identifying the stored media  24 .  
     [0037] Similarly, as a further illustration, a blanket gas signal may be communicated to the controller unit  36  and/or a network  110  indicating that the blanket gas  22  is leaking. Additionally, that signal in one exemplary embodiment includes a tag or be encoded with information relating to the storage tank  30  from which the blanket gas signal originated. This information may include, but is not limited to, a unique storage tank specific tag for identifying the storage tank  30  or a unique blanket gas specific tag for identifying the blanket gas  22 .  
     [0038] With reference to the operation of the gas blanketing regulation or, commonly, the “PAD” valve  64  of FIG. 2 is a device that is able to maintain a constant pressure of the blanket gas  22  within the storage tank  30  by adding blanket gas  22  as needed. More specifically, the PAD valve  64  maintains the protective gaseous environment above any fluid stored in a tank or vessel by using a blanket of gas  22 . The lowpressure gas blanket from the PAD valve  64  fills the void space above the fluid stored in the storage tank  30 . The gas blanket  22  helps prevent outside air, moisture, and other contaminants from entering the storage tank  30 . In addition, the gas blanket of the system provides a head pressure above the fluid within the storage tank  30  to reduce vapor loss which helps protect the storage tank  30  from corrosion. When the blanket gas pressure inside the storage tank  30  decreases, the PAD valve  64  will open, which will allow the blanket gas  22  into the storage tank  30 . Similarly, the PAD valve  64  maintains a constant tank pressure while removing fluid from the storage tank  30 , thereby preventing the storage tank  30  from collapsing.  
     [0039] The DEPAD valve  68 , on the other hand, is able to maintain a constant pressure of the blanket gas  22  within the storage tank  30  by removing vapor or blanket gas  22  from the storage tank  30 . Once removed from the storage tank  30 , the blanket gas  22  may be released into the atmosphere. The blanket gas  22  may also be recycled and may be processed or filtered to again be used as blanket gas  22 .  
     [0040] In at least one exemplary embodiment, the PAD valve  64  and the DEPAD valve  68  may also be combined to create a PAD/DEPAD valve. The PAD/DEPAD valve, as the name suggests, performs the combined function of the two separate valves.  
     [0041] The PAD valve  64 , the DEPAD valve  68 , and the PAD/DEPAD valve may also be combined or incorporated with parameter sensing devices  32 ,  34  as shown in FIG. 5, to create a package valve  126 . With the aid of a controller unit  36 , the package valve  126  is able to sense and regulate the different parameters of the stored media  24  and the blanket gas  22 . In one exemplary embodiment, the package valve  126  may be a PAD valve  64  and a DEPAD valve  68  combined and incorporated with a stored media level sensor  38 , such as a float device. The package valve  126  may be able to the sense the flow of the blanket gas. Moreover, as mentioned above, the package valve  126  and the stored media level sensor  38  may be able to sense and regulate the flow of the blanket gas  22  according to the level of the stored media  24 .  
     [0042] The pressure relief valve or vent  72  and the vacuum relief valve or vent  66  are both utilized in situations that require pressure corrections within the storage tank  30 . In most instances, the pressure relief vent  72  and the vacuum relief valve  66  are used to prevent the explosion or implosion of the storage tank  30 , respectively. For example, if the storage tank  30  is being filled with stored media  24  and the blanket gas  22 , for one reason or another, is not removed to compensate for the addition of the stored media volume, the pressure within the storage tank  30  will increase, thereby threatening the integrity of the storage tank  30 . If not reduced, the pressure may increase to a critical point, and cause the storage tank  30  to explode or leak. To prevent the pressure from increasing to that critical point, the pressure relief vent  72  will allow blanket gas  22  to escape as the blanket gas pressure increases.  
     [0043] In another example, if stored media  24  is being removed from the storage tank  30  and the blanket gas  22  for one reason or another is not added to compensate for the removal of stored media volume, the negative pressure within the storage tank  30  will increase, thereby threatening the integrity of the storage tank  30 . If not corrected, the negative pressure may increase to a critical point and cause the storage tank  30  to implode or cause a leak. To prevent the negative pressure from increasing to that critical point, the vacuum relief valve  66  will intake the necessary blanket gas  22  or air to reduce the negative pressure.  
     [0044] In operation, the gas blanket management system  20  may be configured to accomplish a number of tasks, including the ability of the gas blanket management system  20  to obtain values for the different parameters of the stored media  24 , the blanket gas  22 , the storage tank  30 , and the ability to activate tank controlling devices and alarms. The gas blanket management system  20 , for example, may obtain the temperature of the stored media  24  or of the blanket gas  22 , the pressure of the stored media  24  or of the blanket gas  22 , and/or the flow rate of the stored media  24  or of the blanket gas  22 . Along with the ability to obtain values for the different parameters of the different media, the gas blanket management system  20  in at least one exemplary embodiment may combine two or more parameters of the one or more media to accomplish, as mentioned above, various other functions.  
     [0045] With the combination of two or more parameters of the one or more media, the gas blanket management system  20  may be able to control or monitor the integrity of the storage tank  30 , or be able to control or monitor a tank fill system, a tank extraction or outflow system, a tank level monitoring system, and/or a tank heating system.  
     [0046] In one example, the gas blanket management system  20  may utilize the controller unit  36 , the gas blanket sensor  34 , and the storage tank sensor  32  in combination with the PAD valve  64 , the DEPAD valve  68 , a stored media inflow valve  62 , and a stored media outflow valve  70  to monitor the integrity of the storage tank  30 . More specifically, when the storage tank system is in a steady state during which no stored media  24  or blanket gas  22  is added or extracted from the storage tank  30 , the amount of stored media  24  and blanket gas  22 , and hence their respective associated pressures, should remain constant.  
     [0047] It should be noted, that even though the storage tank  30  is in a theoretical steady state, with no addition or subtraction of either the blanket gas  22  or the stored media  24 , in most instances there will be a diminishing pressure of the blanket gas  22  within the storage tank  30  due to a dissipation of the blanket gas  22 . With the diminishing pressure and the dissipation of the blanket gas  22 , during the steady state, there will be a flow of blanket gas  22  into the storage tank  30  to replenish the dissipating gas and to restore the blanket gas pressure. Therefore, it is assumed, and is well known in the art, that even though the storage tank  30  may be at a steady state with no substantial addition of blanket gas  22  into the storage tank  30 , there may be a small continuous inflow of blanket gas  22  into the storage tank  30  to replenish the dissipating gas and to restore the blanket gas pressure.  
     [0048] It should be further noted, that even though there may be a small continuous inflow of blanket gas  22  into the storage tank  30 , the blanket gas inflow sensor  44  may be calibrated to read as though no blanket gas  22  is flowing. The blanket gas inflow sensor  44  may be calibrated as such for several reasons including ensuring a positive pressure inside the storage tank  30  and preventing a false reading of a gas inflow sensor  44  and/or gas inflow valve or regulator  64 .  
     [0049] If there is a leak in the storage tank  30  or there is a malfunction with either the stored media inflow valve  62  or the gas blanket inflow device  64 , the gas blanketing management system  20  may be utilized to sense a storage tank leak or control device malfunction and may be able to activate an alarm accordingly. A storage tank leak may be caused by a puncture or a faulty storage tank control device, allowing for the escape of the blanket gas or the stored media from the storage tank  30 , or by a faulty PAD valve  64 , PAD/DEPAD valve or stored media inflow valve  62 , thereby allowing for the accidental addition of the blanket gas  22  or the stored media  24  into the storage tank  30 .  
     [0050] Such operation is depicted graphically in an exemplary routine  140  provided in FIG. 6. The routine  140  may begin at a block  142  where the controller unit  36  initiates a diagnostic check of the available sensors, such as one or more stored media sensors  32  and/or one or more gas blanket sensors  34 . Those of ordinary skill in the art will readily recognize that the means of performing the diagnostic check may be accomplished in various ways including single or bidirectional communication between the sensors  32 ,  34  and the controller unit  36  or any other suitable means accomplishing the diagnosis. If at a decision diamond  144 , the diagnostic check  142  determines that one or more of the sensors  32 ,  34  is not functioning properly, the controller unit  36  may activate, at a block  146 , either the stored media sensor alarm  76  or the gas blanket sensor alarm  77 , depending on which of the sensor fails to function properly. If at the decision diamond  144 , the diagnostic check  142  determines that the sensors  32 ,  34  are functioning properly, the stored media sensors  32  and the gas blanket sensors  34 , at a block  148 , will each sense a parameter of their respective media. The parameters being sensed by the sensors  32 ,  34  may include, but are not limited to, the inflow, the outflow, the temperature, the volume, and the pressure of the blanket gas, as well as the inflow, the outflow, the temperature, the volume, and the pressure of the stored media. However, for clarity, the routine  140  will be hereinafter described using a gas blanket inflow sensor  44  and a stored media level sensor  38 .  
     [0051] After the gas blanket inflow sensor  44  at the block  148  senses the gas blanket inflow status, the gas blanket inflow sensor  44 , at a block  150 , may send a signal representative of the gas blanket inflow status to the controller unit  36 . Similarly, after the stored media level sensor  38  at the block  148  senses the stored media level status, the stored media level sensor  38  sends a signal representative of the stored media level status to the controller unit  36 . For example, the storage tank  30  may have a capacity of 3,140,000 ft 3  wherein the stored media level sensor  38  may indicate that the storage tank  30  is filled to half capacity or 1,570,000 ft  3 , and that the height and hence the volume of the stored media is not changing.  
     [0052] Similarly, while the storage tank system is at a steady state, a gas blanket inflow rate of zero may be detected by the gas blanket inflow sensor  44 . The stored media level sensor  38  and the gas blanket inflow sensor  44  may then send a signal representative of the respective level and flow rate to the controller unit  36 . It should be noted that the means of communication between the controller unit  36 , the sensors  38 ,  44 , and the storage tank input and output devices  28 ,  31 , may vary greatly, and may consist of several technologies. More specifically, as mentioned earlier, the controller unit  36  may include a transceiver able to receive and/or transmit signals via a wireless or wire technology. The signals generated by the sensors may be transmitted to the controller unit  36  via a hardwire such as RS485 or telephone technology, or via wireless technology, such as RF radio or Cellular Digital Packet Data (CDPD), or the like. Similarly, the method of transmitting a signal from the controller unit  36 , may be accomplished via any of the above-mentioned or other ways readily recognized by those of ordinary skill in the art.  
     [0053] At a block  152  of FIG. 6, the controller unit  36  may evaluate the signals received from the stored media level sensor  38  and the gas blanket inflow sensor  44 . The signals may be compared to verify that the status of the stored media  24  and the status of the blanket gas  22  correspond to each other. For example, as above, if the signal from the stored media level sensor  38  indicates no change in the media level, the blanket gas inflow rate should correspondingly be zero. Therefore, the signals of the two or more sensors correspond to each other when the signals indicate the same status or change in the storage tank  30 . If at a decision diamond  154 , the signals indicate a corresponding status, control may be passed to the block  142 , where the entire process is then repeated.  
     [0054] If at the decision diamond  154 , the signals do not indicate a corresponding status, control may be passed to a decision diamond  156 , where the signals are further evaluated to determine why the signals do not correspond. If at the decision diamond  156  the blanket gas inflow sensor  44  indicates that there is a blanket gas inflow into the storage tank  30  and the stored media level sensor  38  indicates that there is no change in stored media level, control may then pass to a block  158 . At the block  158 , the controller unit  36  may activate the blanket gas alarm  75 . For example, there may be a puncture or an open vent or valve allowing the blanket gas  22  to escape if the signal from the stored media level sensor  38  indicates no change in the stored media level and the blanket gas inflow sensor  44  indicates a 100 ft 3 /min flow rate. If at the decision diamond  156 , the gas blanket inflow sensor  44  signal indicates that there is no blanket gas inflow, control may be passed to a decision diamond  160 .  
     [0055] If at decision diamond  160 , the stored media level sensor  38  indicates that there is a change of the stored media level in the storage tank  30  and the blanket gas inflow sensor  44  indicates that there is no gas blanket flow rate, then control passes to a block  162  where the controller unit  36  may activate the stored media alarm  74 . For example, if the signal from the stored media level sensor  38  indicates a 3 ft drop in the level of the stored media and the blanket gas inflow sensor  44  indicates a zero flow rate, then there may be a puncture or an open valve allowing the stored media  24  to escape. If, however, at the decision diamond  160 , the stored media level sensor  38  also indicates that there is no change in the level of the stored media  24  in the storage tank  30 , then the controller unit  36  may sense a failure in one of the sensors  38 ,  44  and activate one of the sensor alarms  76 ,  77  at the block  146 .  
     [0056] The routine  140  of FIG. 6 is only one of many examples and applications for which the gas blanketing management system  20  may be used. The number and types of sensors and control devices and combinations thereof, may be used to fulfill a number of regulatory, control, and information gathering functions. Furthermore, the structure and communications set-up for communicating with and controlling the controller unit, the sensors, and the control devices may be local or global. Illustratively, the controller unit  36  in FIG. 3 may be able to communicate with a local communications module  170 . The communications module  170  may be S attached to the storage tank  30  or may be placed near of the storage tank  30 . The communications module  170  may also be an integrated part of the controller unit  36 , or be a wholly independent unit. A user may be able to utilize the communications module  170  to regulate the gas blanketing management system  20  directly, or may be able to utilize the communications module  170  to retrieve or download sensor and/or control device data.  
     [0057] The gas blanketing management system  20  may also be communicatively coupled to a third party system, computer or other communication device. The term “communicatively coupled” shall herein be construed to refer to any instance the gas blanketing management system  20  and/or the controller unit  36  is coupled or linked and is able to transfer and/or receive information, data and/or signals. For example the gas blanketing management system  20  may be communicatively coupled to a monitor located at a gas manufacturing or gas distribution facility responsible for the maintenance of the storage tanks and/or the supply of the blanket gas. The transfer and/or receipt of information may be accomplished in various manners, such as directly or indirectly, hardwire or wireless, simultaneous communication or delayed, and/or unidirectional or bidirectional.  
     [0058] The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom, as modifications will be apparent to those skilled in the art.