Abstract:
A system and method for maintaining overpressure in a logging unit or other pressurized space through interruptions is disclosed. A backup air supply comprising tanks mounted to a frame is operatively connected to the ambient environment of the logging unit through a valve assembly which also connects a conventional pressure setup (e.g., pumps and filters from the external environment). The valve assembly comprises two auto valves, a shuttle valve, and a pressure sensor that allow the logging unit to switch from the conventional external air supply to the tanks when the pressure detected from the conventional air supply falls below a predetermined level. The valve assembly is independently housed and may be mounted or detached from the frame housing the backup tanks.

Description:
STATEMENT OF PRIORITY 
       [0001]    This is a non-provisional application claiming priority to U.S. Provisional Application No. 62/295,964, filed on 16 Feb. 2016, and entitled “Automatic Air Backup System.” The entirety of the provisional disclosure is incorporated herein by reference. 
     
    
     FIELD OF THE APPLICATION 
       [0002]    The present application relates, generally, to a backup system for providing a logging unit or other field environment which is required to be at overpressure with a backup air supply, and a method of automatically switching between the two to avoid interruption. 
       BACKGROUND 
       [0003]    On rigs and other well drilling sites, logging units often contain sensitive electronic equipment which record data from the drilling of a well, equipment which must be protected from contamination from the outside environment. Consequently, these units are often kept at a positive air pressure differential, or overpressure, from the ambient air pressure located outside the logging unit. This air is usually supplied from the ambient atmosphere around the rig itself, utilizing pumps and filters to supply the logging unit with overpressure. 
         [0004]    Most logging units respond to interruptions in air supply, whether from mechanical or human error, by preemptively shutting down the logging equipment and only restarting once the unit has again reached overpressure. Since it may take anywhere from 45 minutes to an hour for overpressure to be reestablished, such errors may result in the loss of several thousand feet worth of drilling logs. 
         [0005]    A need therefore exists for a backup unit which can supply air at overpressure in the absence of a connection between the outside air supply and the pumps. A need additionally exists for a backup unit which can automatically switch between the two air supplies without the need for a manual intervention. 
     
    
     
       DRAWINGS 
         [0006]      FIG. 1A  depicts a perspective view of an embodiment of the backup unit. 
           [0007]      FIG. 1B  depicts a top (plan) view of an embodiment of the backup unit. 
           [0008]      FIG. 1C  depicts a front view of an embodiment of the backup unit. 
           [0009]      FIG. 1D  depicts a side view of an embodiment of the backup unit. 
           [0010]      FIG. 1E  depicts a rear view of an embodiment of the backup unit. 
           [0011]      FIG. 2A  depicts a front view of the valve system housing. 
           [0012]      FIG. 2B  depicts a perspective view of the valve system within the housing. 
           [0013]      FIG. 2C  depicts a cross-sectional view of the valve system within the housing. 
           [0014]      FIG. 2D  depicts a flow diagram illustrating connections within the valve system. 
           [0015]      FIG. 3A  depicts a side view of the valve system in isolation. 
           [0016]      FIG. 3B  depicts a perspective view of the valve system in isolation. 
       
    
    
     SUMMARY OF THE INVENTION 
       [0017]    Embodiments usable within the scope of the present disclosure include a system capable of automatically switching the logging unit environment to a backup air supply system through the use of a valve assembly comprising an external port operatively connected to a standard ambient air supply (e.g., a pump and filter), a backup port operatively connected to a plurality of air tanks mounted in a frame, and an output port operatively connected to both inputs by means of a shuttle valve. Two reset valves control the relative pressures of the standard air supply and the backup air supply; in normal operation, the first reset valve allows the external air supply to circulate through the valve assembly and out the shuttle valve. In the event the external air supply is interrupted, the valves reverse and the first reset valve closes; the second reset valve then opens and allows the backup air tanks to supply air. These pressures may be monitored and controlled by indicator lights, pressure gauges, and regulators. 
         [0018]    In an embodiment of a method of use within the scope of the present disclosure, the logging unit is operatively connected to an external pressure source and a backup pressure source. The backup pressure source is kept at a lower pressure than the external pressure source such that when the external pressure source is active, the backup control valve is closed and the external air is allowed through the shuttle valve. When the external pressure source is interrupted or reduced to a pressure less than the backup pressure, the control valves switch and the backup control valve opens while the external control valve closes, allowing backup air to continue being supplied through the shuttle valve. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Before describing selected embodiments of the present disclosure in detail, it is to be understood that the present invention is not limited to the particular embodiments described herein. The disclosure and description herein is illustrative and explanatory of one or more presently preferred embodiments and variations thereof, and it will be appreciated by those skilled in the art that various changes in the design, organization, order of operation, means of operation, equipment structures and location, methodology, and use of mechanical equivalents may be made without departing from the spirit of the invention. 
         [0020]    As well, it should be understood that the drawings are intended to illustrate and plainly disclose presently preferred embodiments to one of skill in the art, but are not intended to be manufacturing level drawings or renditions of final products and may include simplified conceptual views as desired for easier and quicker understanding or explanation. As well, the relative size and arrangement of the components may differ from that shown and still operate within the spirit of the invention. 
         [0021]    Moreover, it will be understood that various directions such as “upper,” “lower,” “bottom,” “top,” “left,” “right,” and so forth are made only with respect to explanation in conjunction with the drawings, and that the components may be oriented differently, for instance, during transportation and manufacturing as well as operation. Because many varying and different embodiments may be made within the scope of the concepts herein taught, and because many modifications may be made in the embodiments described herein, it is to be understood that the details herein are to be interpreted as illustrative and non-limiting. 
         [0022]    Disclosed is an apparatus and method for providing a backup air supply to a logging unit which can automatically switch between external air and stored air. The apparatus can comprise a frame with a plurality of air cylinders for storing the backup air, as well as a front housing/display with an internal valve assembly, status lights, and gauges for measuring the level of overpressure. 
         [0023]    Turning first to  FIGS. 1A-1E , an embodiment of the backup unit  10  is depicted in perspective, top, front, side, and rear views, respectively. Backup unit  10  comprises a plurality of air tanks  12   a ,  12   b  mounted inside a frame  14 . While the depicted embodiment comprises two tanks, it can be appreciated that other embodiments may utilize a single tank or three or more tanks without departing from the scope of this disclosure. In a preferred embodiment, the tanks are pressurized at 17,000 kPa (2500 psi) and regulated down to 550 kPa (80 psi) by an external regulator (not shown). 
         [0024]    As shown, frame  14  can comprise a forklift slot  16  and lifting lugs  18  on the top of the frame. The depicted embodiment is roughly 1.78 meters (70 inches) in height and 0.58 meters (23 inches) in width and depth, although it can be appreciated that other embodiments may comprise different dimensions without departing from the scope of this disclosure. 
         [0025]    As shown, air tanks  12   a ,  12   b  can be mounted through yoke piece  15  and can comprise at least one manual valve  20 , which are optionally enclosed by valve cover  22  (usually in the course of shipping to/from the worksite.) Valve  20  is always open in normal operation and can be regulated at 550 kPa (80 psi) by an external regulator (not shown). The automatic switching capability will be described in greater detail further herein. Tanks  12   a ,  12   b  are operatively connected to a valve assembly  100 , which can be located within a detachable housing  101 , which may be mounted in frame  14  or stored at a distance from air tanks  12   a ,  12   b . Once depleted, tanks  12   a ,  12   b  are typically shipped off-site for refilling. 
         [0026]    Turning now to  FIG. 2A , an embodiment of the valve assembly  100  is shown in greater detail from the outside, which can include detachable housing  101 , pressure gauge  110 , indicator lights  112  and  114  indicating airflow coming from ambient air or backup air, respectively, and four side ports (i.e., external air port  120 , backup air port  122 , output port  124 , and drain port  126 ). 
         [0027]    Turning now to  FIGS. 2B, 2C, and 2D , the internal view of valve assembly  100 , with housing  101  open, shows the key components in greater detail. These components include valve mount  102 , auto reset valves  104 ,  108 , shuttle valve  105 , T-connections  106 ,  107 , and regulator  109  (labeled in  FIG. 3A ).  FIG. 2D  is a duplicate drawing of  FIG. 2C  showing the various flow paths through the valve assembly  100 , with some numbering eliminated for clarity. In  FIG. 2D , the solid line represents air received from external air port  120 , the dashed line represents air received from backup air port  122 , the dotted/dashed line represents air being moved into the ambient environment through output port  124 , and the dotted line represents fluid drained to drain port  126 . 
         [0028]    With reference to these figures, the fluid connections are now described in greater detail. Air from the ambient environment can be taken in by regulator  109 , through external air port  120 , which can feed through a first auto reset valve  108 . Auto reset valve  108  may comprise a pressure sensor  111 , through which air port  120  can be directly fed into the top side of. This fluid is communicated at a first pressure, which in an embodiment may be 760 kPa (110 psi), but could be greater or lesser without departing from the scope of this disclosure. 
         [0029]    Regulator  109  can be looped with auto reset valve  108  and may act to reduce the fluid to a second pressure, which in an embodiment may be 550 kPa (80 psi), but could be greater or lesser without departing from the scope of this disclosure provided the second pressure is less than the first pressure. Condensation from regulator  109  can be drained through drain port  126 . After exiting auto reset valve  108 , the external air can be fed to T-connection  107 , which operatively connects both shuttle valve  105  and the topside of second auto reset valve  104 . The top side of second auto reset valve  104  can be further coupled to indicator light  112 . 
         [0030]    Meanwhile, air from tanks  12   a  and/or  12   b  (not visible in this drawing) can be delivered through backup air port  122 , from manual valve  20  (depicted in  FIGS. 1A-1E ) and through an external regulator (not shown). Backup air port  122  can connect firstly to second auto reset valve  104  and, if the system is shifted to backup air, through T-connection  106 , which in turn connects indicator light  114  and shuttle valve  105  from the opposite direction, represented by the arrow pointing left to right, at a third pressure which is less than the first pressure. 
         [0031]    Second auto reset valve  104  can be configured to isolate the top side (fluidly coupled to external air port  120  through T-connection  107 ) and the bottom side (fluidly coupled to backup air port  122  through T-connection  106 ) from each other during normal operation. 
         [0032]    In normal operation, the first pressure will be greater than the second and third pressure, and the system will operate with the first auto reset valve  108  open and the second auto reset valve  104  closed, thus, blocking the air originating from backup air port  122 , from going through to T-connection  106  and delivering as output air, sourced from external air port  120 , through the regulator  109 , first auto reset valve  108 , and T-connection  107  (which lights indicator  112 ). Output is represented by the arrow pointing up to down, which leads to output port  124 . Output is also in fluid communication with pressure gauge  110 . Output can include reducer  115 , which lessens the diameter of the connection as it exits shuttle valve  105  towards output port  124 . 
         [0033]    However, in the event of interruption of the external air supply to external air port  120 , the pressure sensor  111  in the first auto reset valve will detect the interruption, and the auto reset valves  104 ,  108  will trip and reverse, closing the first reset valve  108  and opening the second auto reset valve  104 , allowing air from backup air port  122  to go through the T-connection  106 , tripping light indicator  114 , and going through to the shuttle valve  105  to output port  124 . Reducer  115  ensures this process is not instantaneous by allowing gradual pressure bleed-off from the external air, while shuttle valve  105  and the lessening pressure of the external air supply during bleed-off ensure that there is no backwards flow during this process. 
         [0034]      FIGS. 3A-3B  depict an embodiment of the invention, with numbered features identical to  FIGS. 2B-2C , where the housing is absent and the connections between the valves are shown in greater detail. 
         [0035]    Various embodiments, usable within the scope of the present disclosure, have been described with emphasis and these embodiments can be practiced separately or in various combinations thereof. In addition, it should be understood that within the scope of the appended claims, the present invention can be practiced other than as specifically described herein.