Abstract:
A pressure vessel in accordance with the present invention comprises a cover, movable between an open position and a closed position, and a clamp for releasably clamping the cover in its closed position. The clamp includes a handle for manually operating the clamp. The handle is movable between a first position, in which the clamp releasably holds the cover in its closed position, and a second position, in which the cover is free to be moved to its open position. The pressure vessel further comprises locking means, including a latch pin for releasably locking the handle in its first position upon actuation of the latch pin, and actuating means, including a flexible diaphragm which is responsive to an increase in pressure within the pressure vessel, for actuating the latch pin when the pressure within the vessel has reached a predetermined level.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is a § 111(a) application relating to provisional U.S. Application Ser. No. 60/220,055, filed Jul. 21, 2000. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to safety devices for fluid handling apparatus. More particularly, the safety device of the present invention is intended for use with fluid handling apparatus that operate under high pressure to prevent the intentional or unintentional opening of such fluid handling apparatus when the pressure accumulated therein exceeds a predetermined level. 
     BACKGROUND OF THE INVENTION 
     Fluid handling apparatus, generally, are well known and are used in various industries, such as pharmaceutical or other chemical manufacturing, to perform component operations, such as filtration and straining, within larger processes. Fluid handling apparatus may also, however, be used in a process that consists primarily of a filtration or straining operation. From time to time, fluid handling apparatus must be opened for cleaning, declogging or other maintenance or repair. It is often the case that the pressure inside the fluid handling apparatus builds up during operation to unsafe levels. On such occasions, unless the pressure is first released through valves typically provided for this purpose, the operator opening the fluid handling apparatus, or anyone in the vicinity thereof, is at risk of physical injury. Under these conditions, as soon as the cover/clamp of the fluid handling apparatus is disengaged, the internal pressure within the fluid handling apparatus can cause the cover to be flung open with enough force to physically injure the operator or any bystander in the vicinity of the apparatus. In the past, the internal pressure has actually been high enough to cause the cover to be ejected from the fluid handling apparatus, thereby increasing the safety hazard to the operator and bystanders. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the disadvantages and shortcomings of the prior art discussed above by providing a fluid handling apparatus with a safety device designed to keep the cover of the fluid handling apparatus secured in its closed position, such that it cannot be either intentionally or unintentionally opened, for so long as the fluid pressure inside the fluid handling apparatus exceeds a predetermined safe level. The fluid handling apparatus typically includes a securing mechanism with a handle that, when in its engaged position, securely holds the apparatus cover in its closed position. The safety device is designed to lock or latch the handle into its engaged position when the fluid pressure inside exceeds the predetermined safe level. 
     More particularly, a pressure vessel in accordance with the present invention comprises a cover that is movable between an open position and a closed position and a clamp for releasably clamping the cover in its closed position. The clamp includes a handle for manually operating the clamp. The handle is movable between a first position, in which the clamp releasably holds the cover in its closed position, and a second position, in which the cover is free to be moved to its open position. The pressure vessel further comprises locking means, including a latch pin for releasably locking the handle in its first position upon actuation of the latch pin, and actuating means, which is responsive to an increase in pressure within the pressure vessel, for actuating the latch pin when the pressure within the vessel has reached a predetermined level. 
     Other features and aspects of the present invention will become more fully apparent from the following detailed description of the exemplary embodiments, the appended claims and the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the present invention, reference is made to the following detailed description of an exemplary embodiment, considered in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a side elevational view of a liquid filtration apparatus adapted for use with a safety device constructed in accordance with the present invention; 
     FIG. 2 is a cross-sectional view, taken along section line A—A of FIG.  1  and looking in the direction of the arrows, of the liquid filtration apparatus shown in FIG. 1; 
     FIG. 3 is an enlarged view showing a portion of the liquid filtration apparatus and an associated safety device, whose location is shown schematically for reasons of clarity; 
     FIG. 4 is a partially exploded perspective view of one exemplary embodiment of a safety device constructed in accordance with the present invention; 
     FIG. 5 is a fully exploded perspective view of the safety device shown in FIG. 4; 
     FIG. 6 is another fully exploded perspective view of the safety device shown in FIG. 4; 
     FIG. 7 is a fully exploded elevational view of the safety device shown in FIG. 4; 
     FIG. 8 is top plan view of the safety device shown in an assembled state; 
     FIG. 9 is a cross-sectional view, taken along section line F—F of FIG.  8  and looking in the direction of the arrows, of the safety device in its deactivated position; 
     FIG. 10 is a cross-sectional view similar to that of FIG. 9, except that the safety device is shown in its activated position; 
     FIG. 11 is a perspective view showing the interconnection between the safety device of FIGS. 4-10 and the liquid filtration apparatus of FIGS. 1 and 2; 
     FIG. 12 is a front elevational view of the safety device shown in an assembled state; and 
     FIG. 13 is a cross-sectional view, taken along section line H—H of FIG.  12  and looking in the direction of the arrows, of the safety device. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A clear description of the purpose and operation of the safety device of the present invention requires a brief description of the general structure and operation of a typical fluid handling apparatus with which the safety device is intended to be used. Furthermore, while the safety device can be used with many different kinds of fluid handling apparatus, it is especially suitable for use with fluid handling apparatus that are designed for system operating pressures up to 300 pounds per square inch (“psi”) and also especially for use with a liquid filtration or straining apparatus of such design. Accordingly, the following description is of a generic liquid filtration apparatus, the structure and operation of which is generally well known and it being understood that the safety device may also be used with a liquid straining apparatus, as well as with air or gas handling apparatus. 
     With reference now to FIGS. 1 through 3, in general, and FIG. 1, in particular, a typical liquid filtration apparatus  10  includes a vessel body  12  having an interior space  14 , wherein liquid undergoes filtration, and an exterior surface  16 . The liquid filtration apparatus  10  also includes a hatch, such as the vessel cover  18  shown in FIG. 1, that is pivotably connected to the vessel body  12  with a hinge  20  or similar mechanism. With particular reference still to FIG. 1, the vessel cover  18  is moveable in the direction shown by arrow B, between a closed position (shown in solid lines) and an open position (shown in dotted lines). The vessel cover  18  is provided with a vent connection  22  having a pressure-relief valve  26  for a purpose to be described hereinafter. It should be noted that it is not uncommon for the hatch to be flat or to be connected on the side of the vessel body  12 , or both, rather than the lid-like, dish-shaped vessel cover  18  described herein. 
     The vessel body  12  further includes an inlet  30  which allows unfiltered liquid to enter the interior space  14  from the direction shown by arrow C in FIGS. 1-3. As shown in FIG. 3, the inlet  30  is provided with a side opening  32  having a connector fitting  34 . One end  36  of a conduit  38  is connected to the side opening  32  at the connector  34  and the other end  40  of the conduit  38  is connected to a safety device (not shown) in a manner and for a purpose which will both be described hereinafter. The conduit  38  can be made of metal pipe, flexible tubing or any material capable of conducting fluid from the liquid filtration apparatus  10  to the safety device. 
     The vessel body  12  also includes an outlet  42  located on a side opposite the inlet  30 . The outlet  42  provides a means of egress for filtered liquid to exit from the interior space  14  of the vessel body  12  in the direction shown by arrow D in FIGS. 1 and 2. It should be noted that the conduit  38  may be connected to a side opening in the outlet  42 , or at both the inlet  30  and the outlet  42 , rather than only at the inlet  30  as discussed above. 
     The liquid filtration apparatus  10  further includes a restraining mechanism, such as the toggle clamp  44  shown in FIGS. 1-3, for sealably securing the vessel cover  18  in its closed position (see solid lines in FIG. 1) during operation of the liquid filtration apparatus  10 . The toggle clamp  44  has a clamp handle  46  that engages and disengages the toggle clamp  44 . The clamp handle  46  can be pivotably moved, as shown by arrow E in FIGS. 2 and 3, between an engaged position (shown in solid lines), in which the toggle clamp  44  holds the vessel cover  18  sealably and securely onto the vessel body  12 , and a disengaged position (shown in dotted lines), in which the toggle clamp  44  releases the vessel cover  18 . A mounting bracket  48  is affixed to the exterior surface  16  of the vessel body  12  proximate to the clamp handle  46  to provide a location  50  for attaching the safety device (not shown) to the vessel body  12  as will be described hereinafter. 
     The structure of an exemplary embodiment of a safety device constructed in accordance with the present invention will now be described. It should be understood that the use herein of relative spatial terms such as, upper, lower, downwardly, top and bottom, are used to simplify the following description and are not intended to limit the orientation in which the safety device can be designed or used. For instance, the safety device can be mounted and operated sideways or inverted, relative to the orientation that is described herein in connection with the preferred embodiment. 
     Referring to FIGS. 4-7, the safety device  54  includes a body  56 , having a lower body flange  58 , and a separate bottom cover flange  60  (see FIGS. 5-7) having an inlet opening  62  and a threaded connector  64 . The lower body flange  58  and the bottom cover flange  60  are sized and shaped to cooperate with one another to form a diaphragm chamber  66  therebetween with which the inlet opening  62  communicates. The end  40  of the conduit  38  of the liquid filtration apparatus  10  is connected to the inlet opening  62 , using the threaded connector  64 , and delivers a portion of the liquid in the liquid filtration apparatus  10  into the diaphragm chamber  66  for a purpose to be described hereinafter. 
     The safety device  54  also includes a flexible diaphragm  68  that is sized and shaped to fit within the diaphragm chamber  66  and align with the lower body flange  58  and the bottom cover flange  60 . The diaphragm  68  is made of elastomeric material, such as silicone or TEFLON™, and has a first side  70  that faces the lower body flange  58  and an opposite second side  72  that faces the bottom cover flange  60  and the inlet opening  62 . An annular groove  74  is provided on the lower body flange  58  and aligns with a corresponding annular groove  76  provided on the bottom cover flange  60 . A securing mechanism, such as the V-band clamp  78  shown most clearly in FIGS. 4-6, holds the lower body flange  58  and bottom cover flange  60  together, with the diaphragm  68  securely held therebetween. It should be noted that the securing mechanism does not have to be a V-band clamp, but rather, it may be any conventional type of device, such other types of clamps or even bolts, that will hold the lower body flange  58 , diaphragm  68  and bottom cover flange  60  together securely in air-tight fashion. The diaphragm  68  deforms slightly into the grooves  74 ,  76  of the lower body and bottom cover flanges  58 ,  60 , respectively, and is thereby prevented from slipping or sliding out from between the flanges. The diaphragm  68  is moveable between a deactivated position (see FIG. 9) and an activated position (see FIG. 10) for purposes to be discussed hereinafter. 
     The body  56  of the safety device  54  further includes an upper body  80 , having a lower chamber  82  and an upper chamber  84 , and a latch pin guide tube  86  that connects the lower body flange  58  to the upper body  80 . The latch pin guide tube  86  has a through bore  88  with one opening  90  (see FIG. 6) in communication with the diaphragm chamber  66  and another opening  92  (see FIGS. 4 and 5) in communication with the lower chamber  82  of the upper body  80 . The upper body  80  is also provided with a pair of mounting ears  94 ,  96  having holes  98 ,  100 , respectively, each of which is sized and shaped to receive a bolt for attaching the body  56  of the safety device  54  to the vessel body  12  of the liquid filtration apparatus  10  at the location  50  using the mounting bracket  48 . It should be noted that any conventional means for securely mounting the body  56  of the safety device  54  to the vessel body  12 , such as clamping, welding or clipping, would be acceptable and, therefore, the mounting ears  94 ,  96  may be substituted or eliminated without affecting the utility or function of the present invention. 
     The safety device  54  further includes a latch pin  102  that is slideably mounted for reciprocating movement between a retracted position (see FIG. 9) and an extended position (see FIG.  10 ). The latch pin  102  has a small diameter portion  104 , a large diameter portion  106  and an annular shoulder  108  therebetween. A large diameter bushing  110  is positioned securely within the bore  88  at the opening  90  and is sized and shaped to slideably receive the large diameter portion  106  of the latch pin  102 . A small diameter bushing  112  is positioned securely within the bore  88  at the other opening  92  thereof and slideably receives the small diameter portion  104  of the latch pin  102 . A coil spring  114  is housed within the bore  88 . More particularly, one end  116  of the coil spring  114  abuts the small diameter bushing  112  and the other end  118  abuts the annular shoulder  108  of the latch pin  102 , with the small diameter portion  104  of the latch pin  102  passing therethrough. It is possible to eliminate the bushings  110 ,  112  altogether from the safety device  54 , thereby reducing the number of components necessary to assemble the safety device  54 . Also, it is not required that the latch pin  102  have a small diameter portion  104 , a large diameter portion  106 , an annular shoulder  108 , or any of the foregoing, as long as it can reciprocate between an extended position and a retracted position, for reasons which will be made clear hereinafter. Furthermore, alternative constructions of the body  56  are possible where, for example, the latch pin guide tube  86  includes a window or opening through which the latch pin  102  and coil spring  114  are visible. 
     Referring specifically to FIG. 9, the coil spring  114  urges the latch pin  102  toward its retracted position, in which it projects downwardly from the opening  90  and into the diaphragm chamber  66 . More particularly, as can be seen in FIG. 9, when the latch pin  102  is in its retracted position, its large diameter portion  106  extends into the diaphragm chamber  66  and pushes against the first side  70  of the diaphragm  68 , thereby moving the diaphragm  68  into its deactivated position. When in its deactivated position, the diaphragm  68  assumes a concave shape relative to the large diameter portion  106  of the latch pin  102  such that its second side  72  conforms to the inner surface of the bottom cover flange  60 . 
     With reference particularly to FIGS. 4-5 and  11 - 12 , the safety device  54  further includes an L-shaped latch plate  120  having a first leg  122  with a rectangular hole  124  and an upper arcuate portion  126 . The upper arcuate portion  126  is sized and shaped to conform to the outer surface of the clamp handle  46  of the toggle clamp  44  of the liquid filtration apparatus  10 . As can be seen in FIG. 11, the latch plate  120  is securely affixed to the clamp handle  46 , by conventional means such as welding, bolting or soldering, such that the arcuate portion  126  contacts the clamp handle  46 . 
     With continued reference to FIGS. 4-5 only, the latch plate  120  also has a second leg  128  that is sized and shaped to be removeably received within the lower chamber  82  of the upper body  80 . In addition, the second leg  128  has a latch pin hole  130  that is sized and shaped to receive the small diameter portion  104  of the latch pin  102 . When the second leg  128  is fully received within the lower chamber  82 , the latch pin hole  130  aligns with the small diameter bushing  112  positioned at the opening  92  of the bore  88 . 
     With reference now to FIGS. 4-8 and  13 , the safety device  54  also includes a latch lever  132  that moves, as shown by arrow G in FIGS. 8 and 13, between a rest or home position (see FIGS. 8 and 13) and a deflected position (not shown). The latch lever  132  has an end portion  134  that is sized and shaped to be received within the upper chamber  84  of the upper body  80  and has a pivot pin hole  136 . There is also a pivot pin hole  138  in the top wall  140  of the upper chamber  84  that aligns with the pivot pin hole  136  in the end portion  134  of the latch lever  132  when the end portion  134  is fully inserted into the upper chamber  84 . A pivot pin  142  is inserted through the aligned pivot pin holes  136 ,  138  thereby pivotably attaching the latch lever  132  to the safety device  54 . 
     The latch lever  132  also has a tapered portion  144  that extends outwardly from the upper chamber  84  and is sized and shaped to be received through the rectangular hole  124  of the first leg  122  of the latch plate  120 . The tapered portion  144  has a camming side  146  that terminates at a notch  148  which forms a latching shoulder  150  on one side of the latch lever  132 . A spring guide notch  152  is provided on the opposite side of the latch lever  132  proximate to the end portion  134 . One end  154  of a second coil spring  156  rests in the spring guide notch  152  and the other end  158  of the coil spring  156  is received within a recess  160  provided in a side wall  162  of the upper chamber  84  (see, particularly, FIGS.  5  and  13 ). The coil spring  156  urges the latch lever  132  towards its rest or home position (see FIGS.  8  and  13 ), in which a side portion  164  of the latch lever  132  abuts an opposite side wall  166  of the upper chamber  84 . The tapered end  144  of the latch lever  132  also has a lock-out hole  168  that is sized and shaped to receive a conventional pad lock for a purpose to be discussed hereinafter. 
     Prior to, and during, operation of the liquid filtration apparatus  10 , the vessel cover  18  must be secured in its closed position (see solid lines in FIG. 1) on the vessel body  12 . Thus, prior to commencing filtration, the clamp handle  46  is manually moved into its engaged position, thereby engaging the toggle clamp  44  to securely hold the vessel cover  18  in its closed position. With the vessel cover  18  thus held closed, filtration of the liquid proceeds in the interior space  14  of the vessel body  12 . The liquid to be filtered enters the interior space  14  of the vessel body  12  through the inlet  30 , from the direction shown by arrow C in FIGS. 1-3. After being filtered, the liquid exits from the interior space  14  through the outlet  42 , in the direction shown by arrow D in FIGS. 1 and 2. 
     During filtration, there is typically a pocket of air trapped in the interior space  14  of the vessel body  12  between the surface of the liquid undergoing filtration and the underside of the vessel cover  18 . It is normal that as the pressure increases in the interior space  14 , the pocket of air becomes increasingly compressed. When the toggle clamp  44  is disengaged, if the fluid pressure in the interior space  14  has not been reduced to a safe level, the compressed air will instantaneously expand within the interior space  14  and force the vessel cover  18  out of its closed position quickly, forcefully and uncontrollably. This can potentially result in physical injury to the person who disengages the toggle clamp  44 . 
     To reduce the risk of such injury, when the fluid pressure inside the vessel body  12  reaches unsafe levels, prior to disengaging the toggle clamp  44 , the fluid pressure must be reduced by opening the pressure-relief valve  26  of the vent connection  22  on the vessel cover  18 , which will allow the compressed air and some of the pressurized fluid to escape therethrough. Until enough pressurized air and fluid escapes through the pressure relief valve  26  to reduce the fluid pressure to a safe level, disengagement of the toggle clamp  44 , either intentional or unintentional, must be prevented. This can be achieved if the clamp handle  46  is locked in its engaged position for so long as the fluid pressure inside the liquid filtration apparatus  10  remains above a predetermined safe level. The safety device  54  of the present invention is capable of preventing both intentional and unintentional movement of the clamp handle  46  out of its engaged position as will be described hereinafter. 
     The latch plate  120  of the safety device  54  is securely affixed to the clamp handle  46  so that the second leg  128  extends toward the upper body  80  of the safety device  54  which is mounted at the location  50  on the exterior surface  16  of the vessel body  12  of the liquid filtration apparatus  10 . As the clamp handle  46 , with the latch plate  120  affixed thereto, is moved into its engaged position, the latch plate  120  approaches the upper body  80  of the safety device  54  and the rectangular hole  124  of the first leg  122  receives the tapered portion  144  of the latch lever  132 . The camming side  146  of the tapered portion  144  rides along a side edge  170  of the rectangular hole  124 , thereby deflecting the latch lever  132  away from its rest position until the latching shoulder  150  reaches the side edge  170 . When the latching shoulder  150  reaches the side edge  170 , the latch lever  132  snaps back into its rest position (due to the force exerted by the coil spring  156 ), the side portion  164  of the latch lever  132  meets the opposite side wall  166  of the upper chamber  84  and the latching shoulder  150  grips the side edge  170  of the rectangular hole  124  (see, e.g., FIGS.  8  and  12 ). Simultaneously with the foregoing chain of events, the second leg  128  of the latch plate  120  is inserted into the lower chamber  82  of the upper body  80  of the safety device  54  and the latch pin hole  130  aligns with the small diameter bushing  112  and opening  92  of the bore  88  of the latch pin guide tube  86 . 
     The foregoing arrangement prevents unintentional movement of the clamp handle  46  and affixed latch plate  120  away from the safety device  54  and, thus, locks the clamp handle  46  in its engaged position. The latch lever  132  can be manually deflected from its rest position, and the latch plate  120  and clamp handle  46  thereby released, by exerting pressure on the camming side  146  thereof which will deflect the latch lever  132  away from the opposite side wall  166  of the upper chamber  84  and release the grip of the latching shoulder  150  on the side edge  170  of the rectangular hole  124 . The clamp handle  46  can then be moved away from the safety device  54  and vessel body  12  to its disengaged position (shown in dotted lines in FIG.  2 ). 
     With reference to FIGS. 9 and 10, once the filtration process begins and liquid is entering the vessel body  12  through the inlet  30 , pressurized fluid will be diverted through the conduit  38  and the inlet opening  62  of the lower cover flange  60  of the safety device  54  into the diaphragm chamber  66  as shown by arrows G. The pressurized fluid that enters the inlet opening  62  and diaphragm chamber  66  will be a small stream of the inlet liquid that is to be filtered, or sometimes air from the aforementioned and ever-present air pocket. At times, both liquid and air will enter the diaphragm chamber  66  through the conduit  38  and the inlet opening  62 . When the pressurized fluid enters the diaphragm chamber  66 , it exerts a force, in the direction shown by arrows G, against the second side  72  of the diaphragm  68 . As long as the pressure inside the in the interior space  14  of the vessel body  12  remains at a safe level, the force exerted by the pressurized fluid on the second side  72  of the diaphragm  68  will not be sufficient to move the diaphragm  68  from its deactivated position (FIG. 9) against the force of the coil spring  114 . 
     The safety device  54  operates as follows to prevent intentional movement of the clamp handle  46  to its disengaged position while the pressure in the interior space  14  of the vessel body  12  remains at an unsafe level. Referring specifically to FIG. 10, when the fluid pressure inside the vessel body  12  reaches a dangerous level, i.e., about 3 psi or greater, the pressurized fluid that enters the diaphragm chamber  66  will exert sufficient pressure, in the direction indicated by arrows G, to move the diaphragm  68  to its activated position, against the force exerted by the coil spring  114 . In its activated position, the first side  70  of the diaphragm  68  is urged against and conforms to the inner surface of the lower body flange  58 . Furthermore, when the diaphragm  68  moves to its activated position, it will overcome the countervailing force of the coil spring  114  and urge the latch pin  102  into its extended position, which will cause the small diameter portion  104  of the latch pin  102  to extend out from the upper opening  92  of the bore hole  88  of the latch pin guide tube  86  and through the latch pin hole  130  of the second leg  128  of the latch plate  120 . Once the small diameter portion  104  of the latch pin  102  is received through the latch pin hole  130  of the second leg  128 , the second leg  128  cannot be withdrawn from the lower chamber  82  of the upper body  80  of the safety device  54 , which, in turn, prevents the latch plate  120  from being moved away from the safety device  54  and the clamp handle  46  from being moved away from the vessel body  12  to its disengaged position (see dotted lines in FIG.  2 ). The coil spring  114  will be able to overcome the force of the pressurized fluid when the fluid pressure drops to about 2 psi or less, and will then urge the latch pin  102  back into its retracted position (see FIG.  9 ). As the latch pin  102  moves into its retracted position, the large diameter portion  106  of the latch pin  102  will deflect the diaphragm  68  back into its deactivated position. 
     Thus, when the fluid pressure inside the vessel body  12  is high enough (i.e., 3 psi or greater) to move the diaphragm  68  to its activated position (FIG.  10 ), the clamp handle  46  is locked in its engaged position (shown in solid lines in FIGS.  2  and  3 ), thereby preventing disengagement of the clamp  44  and opening of the vessel cover  18 . Furthermore, because the latch pin  102  operates independently of the latch lever  132 , when the latch pin  102  extends to latch the second leg  128  of the latch plate  120  as described above, the clamp handle  46  is locked into its enagaged position regardless of whether the latch lever  132  is manually deflected to release its grip on the latch plate  120 . Thus, even intentional disengagement of the clamp  44  and opening of the vessel cover  18  is prevented when dangerously high fluid pressures exist inside the liquid filtration apparatus  10 . Lastly, both intentional and unintentional movement of the clamp handle  46  to its disengaged position can be prevented by use of a conventional pad lock inserted through the lock-out hole  168  of the latch lever  132 . Such use of a conventional lock and the lock-out hole  168  will prevent withdrawal of the tapered portion  144  of the latch lever  132  from the rectangular hole  124  of the first leg  122  of the latch plate  120 , regardless of the fluid pressure inside the liquid filtration apparatus  10 , and will also prevent movement of the latch plate  120  and the clamp handle  46  away from the safety device  54 , regardless of whether the latch pin  102  is extended. 
     It will be understood that the embodiment described herein is merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the present invention. For instance, as already stated, the safety device  54  of the present invention may be used with different types of fluid handling apparatus besides the liquid filtration apparatus described above, including liquid straining apparatus and air or gas filtration apparatus as well as fluid handling apparatus designed for system operating pressures other than 300 psi. In addition, where it is determined that a fluid pressure other than 3 psi is indicative of dangerous system operating pressures inside the fluid handling apparatus, which will depend upon the particular fluid handling apparatus and fluid system therein, the safety device  54  can be designed such that it will activate at different fluid pressures. The safety device  54  can be altered to activate at a different fluid pressure by utilizing a diaphragm  68  made of another flexible, resilient material requiring a different amount of force to be moved to its activated and deactivated positions. Alternatively, another coil spring  114  can be used that has a different spring force that is appropriate for the particular operating conditions. Further, both a different diaphragm  68  and a different coil spring  114  can be used in the safety device  54  to alter the force necessary to extend the latch pin  102  and thereby latch the strike plate  120  to the safety device  54  and lock the clamp handle  46  in its activated position. All such variations and modifications as are described above, including those discussed within the detailed description of the preferred embodiment, are intended to be included within the scope of the present invention.