Safety apparatus for disconnects and/or valves
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to a safety apparatus to prevent the tampering or inadvertent human error in operating a tank disconnect or a valve under pressure. More particularly, this invention relates to a disconnect and/or valve safety cover operated with a spring extending means which does not retract unless an air flow is flowing through a pneumatic line whereby the disconnects and/or the valves are covered by the safety cover and not operable except under safe operation conditions. 
     2. Description of the Prior Art 
     Safety management of processing gases used in the manufacture of semiconductor devices is very important in the integrated circuit (IC) industry. Particularly, a wide variety of toxic, corrosive, or flammable processing gases are used in the integrated circuit fabrication lines. These hazardous gases must be managed in a &#34;fail safe&#34; manner to prevent leakage into uncontrolled areas. Other than the gas pipes used to contain and transmit the gases from the storage tanks, different kinds of disconnects and valves for controlling the flow of gases through these pipe lines are designed and installed with protective features to increase the safety of the gas management programs. 
     Recently, with the advent of low cost intelligent microprocessors, the operation and control of the valves have been shifting to rely more on electronic sensors and computers. The operation of the entire gas management system may be continuously monitored through a plurality of sensors and controlled by an on-line computer. Safety prevention networks prevent the disconnects and valves from being manually operated unless certain conditions are satisfied. However, for the purposes of maintenance and for a few exceptional operation conditions, disconnects and valves may be provided with a &#34;manual override&#34; option which would allow an operator to bypass the usual protective functions in operating such disconnects and valves. The safety of such gas system could be jeopardized if a manual override is inadvertently set or if someone intentionally overrides the protective measures with an intention to sabotage. 
     An on-line automatic pressure interlock device is marketed by Persys Technology Ltd., referred to as &#34;TRIDEX on-line auto pressure interlock&#34; which includes an apparatus to prevent inadvertent disconnection of a gas line in a pressurized system, e.g. a cylinder connection in a gas cabinet. The disclosed safety apparatus includes a cap which covers a tank connection such that human errors in disconnecting gas tank connections may be prevented. The cap position is controlled by an interlock controller which uses the pressure transducers to monitor the on-line pressure for controlling the position of the cap. The safety apparatus disclosed by Persys Technology is useful in providing additional protection, however it is not &#34;fail safe&#34;. Since the interlock controller relies on the pressure signals from the pressure transducers for controlling the cap position the protection provided by the TRIDEX device may not be available during a power failure or other types of system malfunctions which may render the pressure transducer data to be erroneously measured or received by the interlock controller. The interlock controller itself may fail to properly control the cap. There is still a need to provide a safety apparatus which is fail safe and does not rely on external power source to provide the protection required by a gas management system even in the time of a power failure or system malfunction. 
     SUMMARY OF THE PRESENT INVENTION 
     It is therefore an object of the present invention to provide a safety apparatus which is capable of preventing unsafe operation of a disconnect and/or a valve without relying on an external electric power source. 
     It is another object of this invention to provide a safety apparatus including a spring extending means which naturally urges a safety cover to cover the disconnect and/or the valve thus preventing the disconnect and/or the valve from being inadvertently operated in any individual or combination system failure whereby the safety cover always operates in a fail safe mode. 
     It is a further object of the present invention to provide a safety apparatus which is simple in design and can be manufactured inexpensively. 
     It is a further object of the present invention to provide a safety apparatus which can be installed to retrofit most existing disconnects and/or valves without requiring substantial software or hardware changes. 
     Briefly, in a preferred embodiment, the present invention comprises a safety apparatus which includes a covering means for covering a disconnect and/or a valve and an urging means disposed near the covering means. The urging means urges the covering means to cover the disconnect and/or the valve. The urging means further has a hydraulic retraction mechanism for retracting the covering means from the disconnect and/or the valve only when an external retracting command successfully activates a retracting force on the retracting mechanism. Therefore, the disconnect and/or the valve is covered by the covering means and is prevented from being inadvertently operated in a system failure or under an unsafe operation condition. 
     An advantage of the present invention is that it provides a safety apparatus which is capable of preventing unsafe operation of a disconnect and/or a valve without relying on an external electric power source. 
     Another advantage of the present invention is that it provides a safety apparatus including a spring extending means which naturally urges the safety cover to cover the disconnect and/or the valve thus preventing the disconnect and/or the valve from being inadvertently operated in any individual or combination system failure whereby the safety cover always operates in a fail safe mode. 
     Another advantage of the present invention is that it provides a safety apparatus which is simple in design and can be manufactured inexpensively. 
     Another advantage of the present invention is that it provides a safety apparatus which can be installed to retrofit most existing disconnects and/or valves without requiring substantial software or hardware changes. 
    
    
     These and other objects and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment which is illustrated in the various drawing figures. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a safety apparatus according to the present invention attached to a pigtail pipe near a disconnect and a valve; 
     FIG. 2 is perspective view of the safety cover of the apparatus of FIG. 1; 
     FIG. 3A and FIG. 3B are, respectfully, top and cross-sectional side views of the safety cover of FIG. 2 with the view of FIG. 3B taken along the line 3B--3B of FIG. 2; and 
     FIG. 4A and FIG. 4B are, respectfully, front and side views of a pipe fixture plate of the apparatus of FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 is a perspective view of a safety apparatus according to the present invention and generally referred to by a numeral 10. The safety apparatus 10 comprises a covering means in the form of an elongated semicircular safety cover 12. The safety apparatus 10 further comprises an urging means to axially urge the safety cover 12 as illustrated by the arrow between a first position wherein it covers a tank-pipe disconnect 13 and a second position whereat the valve disconnect 13 is exposed. When in the first position, the disconnect 13 is covered and thereby precluding access by a wrench or other tool. However, when the cover 12 is in the second position, the disconnect 13 is exposed and vulnerable to access by a wrench or other tool. As illustrated herein the safety cover 12 covers only the tank-pipe disconnect 13. However, depending on the application, the safety cover 12 may cover both the disconnect 13 and a valve 14 of a cylinder 15. The urging means includes a pneumatic cylinder 16 connected to a pneumatic line 18, and a spring actuated extending arm 22 which is urged by a spring 23 in turn urging the safety cover 12 to cover the disconnect 13. The cover 12 does not retract unless a pneumatic air flows through the pneumatic line 18 causing the pneumatic cylinder 16 to overcome the force of the spring 23. The pneumatic cylinder 16 is controlled by a gas system controller 24 which controls and activates a pneumatic air to flow through the pneumatic line 18 and thereby sending pneumatic activating commands to the pneumatic cylinder 16. Therefore, disconnect 13 is covered by the safety cover 12 unless the controller 24 issues a pneumatic activating command to retract the safety cover 12. This assures that the safety cover 12 covers the disconnect 13 and/or the valve 14 in the time of a power outage or a pneumatic system failure. The safety apparatus 10 thus operates continuously in a &#34;fail safe&#34; mode without depending on the availability of an external power supply. 
     In the preferred embodiment, a Clippard stainless steel pneumatic cylinder Model SSR-05-01-1/8 manufactured by Clippared Instrument Laboratory, Inc. is used. The SSR-05-01-1/8 pneumatic cylinder has a threaded rod to fit a 3/8. inch bore, i.e. a bore 25 in FIGS. 2 and 3A, with the extending arm 22 allowing a maximum stroke of one and one-eighth inches. It uses a spring having an urging force of approximately thirteen pounds. The pneumatic flow in line 18 is controlled by controller 24. For those skilled in the art, the internal structure of a pneumatic cylinder, the functions of different components, and the applications to a gas management system are well known. A wide variety of pneumatic cylinders are available as disclosed in Catalog 784 &#34;Clippard Stainless Steel Cylinders&#34;, published by Clippard Instrument Laboratory. 
     The safety apparatus 10 further includes a pipe fixture plate 26 of which the upper portion is attached to the cylinder 16 and the lower portion is attached to a pigtail pipe 28. The pigtail pipe 28 is connected to the disconnect 13 and the valve 14. The pipe fixture plate 26 provides for securely attaching the safety apparatus 10 to a pipe near the disconnect 13 and the valve 14. Therefore, the installation of the safety apparatus 10 to an existing piping system does not require re-routing or configuration changes of the pipes or valves. The pipe fixture plate 26 may be conformed to fit the existing piping and valve arrangements and positions such that the safety apparatus 10 protects the associated disconnect 13 and/or the valve 14 from being tampered or inadvertently operated. 
     FIG. 2, FIGS. 3A and 3B further illustrate that the safety cover 12 which is semicircular with a hollow internal space 32 for receiving and covering the disconnect 13 and/or the valve 14 therein. The safety cover 12 has an open end 34 and an attachement end 36 opposite the open end 34. The attachment end 36 has the threaded bore 25 to engage and securely attach to the extending arm 22. The attachment end 36 further has a downward U-shaped opening 42 to fit around the pigtail pipe 28 thereby allowing free lateral movement of the safety cover 12 along the pigtail pipe 28. The safety cover has a rotational freedom around the extending arm 22 provided by the attachment between the attachment end 36 and the threaded bore 25. Depending on the application, the safety cover 12 can be rotated such that the U-shaped opening 42 is aligned horizontally whereby the position of the vale disconnect 13 and/or the valve 14 can be visually inspected. The open end 34 is disposed on the opposite end of the semicircular safety cover 12 which is a complete open end as shown. Depending on the application, the open end 34 can be expanded to comprise a larger semi-circular cover (not shown) to simultaneously cover the valve 14 when the spring extending means 22 is in its extended position such that both the disconnect 13 and the valve 14 are protected by the safety apparatus 10. 
     FIGS. 4A and 4B show a front view and a side view of the pipe fixture plate 26. The pipe fixture plate 26 has an upper plate segment 54 and a lower plate segment 56. The upper plate segment 54 has a passage-hole 58 for receiving and supporting the pneumatic cylinder 16. A nut 59 engages a threaded end of the pneumatic cylinder 16 to lock the cylinder 16 securely in place to the plate segment 54 (FIG. 1) A bottom edge 62 of the upper plate segment 54 includes a first semi-circular pipe fitting concave opening 64. The lower plate segment 56 has a pipe-fitting edge 68 with a second pipe-fitting semi-circular concave opening 72. The first and the second pipe-fitting concave openings 64 and 72 face each other to circumferentially surround the pigtail pipe 28. 
     A clamping means clamps the upper plate segment 54 to the lower plate segment 56 to securely attach the safety apparatus 10 to the pigtail pipe 28 near the disconnect 13. The clamping means includes a pair of threaded screws 76 and a pair of threaded bores 78 in the upper plate segment 54, and a pair of bores 80 in the lower plate segment 56. The pair of threaded screws 76 are positioned in the bores 80 and threaded in the bores 78 to secure the upper and lower plate segments 54 and 56 together around the pipe 28. 
     Although the present invention has been described in terms of the presently preferred embodiment, it is to be understood that such disclosure is not to be interpreted as limiting. Various alternations and modifications will no doubt become apparent to those skilled in the art after reading the above disclosure. Accordingly, it is intended that the appended claims be interpreted as covering all alternations and modifications as fall within the true spirit and scope of the invention.