Abstract:
A valve security guard is provided for a storage tank having a valve for dispensing material from the tank and includes a cover with a closed end and an interior with an open end for enclosing a valve handle, and a shaft member that extends through apertures in the cover that is lockable in a fixed position located behind the valve handle to secure the cover thereon.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates in general to a security guard for a valve on a storage tank and more specifically concerns high strength valve guards that serve as a deterrent to the theft of toxic or hazardous materials. 
     2. Description of the Prior Art 
     Various types of valve security guards are known in the art for placement over valves and other regulating type devices used on storage containers to prevent any unlawful operation thereof. Examples of these prior art devices are disclosed in U.S. Pat. Nos. 4,380,247; 4,513,773; 4,254,888 and 4,899,781. Although the guards disclosed in such patents are useful for their designed purpose, none of them are structured to prevent unauthorized use of a dispensing valve for an anhydrous ammonia storage tank. 
     SUMMARY OF THE INVENTION 
     The present invention provides a valve security guard for a storage tank having a valve for dispensing material from the tank, which valve includes a valve casing, a valve stem that extends outwardly from the casing and an operating handle at the outer end of the stem. The security guard is primarily formed from a cover with a closed end and an interior with an open end for enclosing the valve handle and means for securing the cover on said handle. The securing means is formed of apertures in said cover and an elongated shaft member that extends through said apertures and is lockable in a fixed position located behind the handle to secure the cover thereon. 
     The cover interior has inner and outer chambers formed in a tiered configuration so that the outer chamber has a diameter greater than the inner chamber to define a circular interior ledge and the handle is received in the inner chamber. Preferably, a slip ring that is sized to be received within the inner chamber of said cover is located intermediate the valve handle and the periphery of the inner chamber. Further, the guard includes a shield means with a central opening through which the valve stem can be positioned. The shield means is of a size for being positioned within said outer chamber of the cover interior to seat against the interior ledge for substantially closing off the inner chamber to increase the security of the guard. 
     The foregoing and other advantages of the present invention will appear from the following description. In the description, reference is made to the accompanying drawings, which form a part hereof, and in which there is shown by illustration, and not of limitation, a specific form in which the invention may be embodied. Such embodiment does not represent the full scope of the invention, but rather the invention may be employed in a variety of embodiments, and reference is made to the claims herein for interpreting the breadth of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of a preferred embodiment of the valve security guard of the present invention; 
     FIG. 2 is an exploded side view of the security guard of FIG. 1 shown together with a valve assembly; 
     FIG. 3 is a cross-sectional view of the security guard of FIG. 1 assembled in position on the valve assembly of FIG. 2; 
     FIG. 4 is a side view of the security guard of FIG. 1 positioned on the valve assembly of FIG. 2; 
     FIG. 5 is a cross-sectional view of a cover and a shaft member forming part of the security guard FIG. 1; 
     FIG. 6 is a cross-section similar to that shown in FIG. 5 but with the shaft member viewed from opposite side; and 
     FIG. 7 is a partially exploded plan view of the cover, shaft member and locking bar for the shaft member. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention is designed to provide a valve security guard shown generally at  10  in FIG. 1 for a storage tank. The security guard  10  is particularly appropriate for use with storage tanks holding toxic or other dangerous materials as the structure of the guard is made of high strength and tamper resistant materials in order to provide a highly effective securement device. 
     The security guard  10  principally includes a cover  11  and an elongated U-shaped shaft member  12  designed to coact together to retain the cover in a fixed position on the handle. In addition to the cover  11  and shaft member  12 , the security guard  10  preferably includes a slip ring  13 , a disk shaped shield means  14  and a shield ring  15  in addition to spacing washer  16  as needed, all for the purposes as described below. 
     With reference now to FIGS. 1,  2  and  3 , the cover  11  is generally of a sleeve shape and has a closed outer end  18  and an interior cavity  19  having an open end  20 . The interior cavity  19  is in a tiered configuration with a circular shaped inner chamber  21  and an outer circularly shaped chamber  22  having a diameter larger than that of the inner chamber  21  to form an interior ledge  23 . As is best shown in FIG. 1, the sidewall  17  of the cover  11  is formed with two pairs of opposed aperture  25  through which the shaft member  12  is disposed, as can clearly be seen from FIGS.  1  and  5 - 7 . 
     The shaft member  12  is of an elongated U-shaped configuration having a rounded end  27  and opposite free ends  28  and  29  that are designed to coact with a locking bar  30  to secure the shaft member  12  in place. The shaft member  12  and locking bar  30  are manufactured by Kryptonite Corp. and are of a construction well-known in the art. 
     Referring again to FIGS. 1,  2  and  3 , the interior cavity  19  of the cover  11  is designed to serve as a housing for an operating handle  34  of a valve assembly  35  that further includes a valve body  36 , a valve stem  37  and locking mounting nuts  38  and  39  for securing the stem  37  with the body  36 . As can be seen from FIG. 3, the valve assembly operating handle  34  is received within the inner chamber  21  of the cavity  19 . Also enclosed within the inner chamber  21  is the slip ring  13  that is sized for seating in the chamber  21  in such fashion that it is free to rotate relative to the cover  11 . The use of the slip ring  13 , although not essential to the present invention, is highly desirable as without the slip ring  13 , it may be possible to tilt the cover  11  against the handle  34  to obtain unauthorized actuation of such handle. Obviously, the slip ring  13  prevents such unauthorized action by permitting the cover  11  to rotate without actuation of the valve assembly  35 . 
     In like fashion, the shield  14  is also not essential to the present invention but is highly helpful in preventing tampering with the valve assembly  35  by means of the open end  20  of the interior cavity  19 . The shield  14  includes a center hole  40  so that the shield can be positioned on the valve stem  37  intermediate the handle  34  and the locking nuts  38  and  39 . As can best be seen in FIG. 3, the shield  14  has a diameter approximately equal to the inner diameter of the outer chamber  22  of the cavity  19  and seats against the cover interior ledge  23  to seal off the cavity inner chamber  21 . 
     The integrity of the security guard  10  is further enhanced through the use of the shield ring  15  that is designed to fit over the locking nuts  38  and  39  and prevent access thereto by unauthorized personnel. The washers  16  serve simply as spacers between the shield  14  and operating handle  34  to maintain the shield  14  in proper position for completely sealing off the inner chamber  21 . Accordingly, the security guard of the present invention provides a highly secure means for preventing unauthorized operation of the valve assembly  35 , as indicated by FIG.  4 . 
     Although the invention has been described with respect to a preferred embodiment thereof, it is to be understood that it is not to be so limited, since changes and modifications can be made therein which are within the full intended scope of this invention as defined by the appended claims.