Abstract:
A vapor plate for covering a manhole of a cargo transport tanker, the vapor plate including a plate member and one or more push rod assemblies. Each push rod assembly includes a guide tube extending through said plate member and a push rod extending through the guide member. A rod of the push rod moves linearly and rotationally within said guide tube. An adjustable collar of a resistance mechanism may be fixed to the rod so that the collar engages a spring allowing a user to generate a resistive clamping force by pushing downward on the push rod. A user may clamp the rim of a manhole between a lower handle of the push rod and the plate member with the resistive force by positioning the lower handle underneath the rim after generating the resistance force. The push rod assembly is sealed to prevent vapor leakage.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    None. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention is in the field of vapor plates used to cover manholes of transport tankers, such as an over-the-road tank trailer and tank railcars. 
         [0004]    2. Description of Related Art 
         [0005]    Vapor plates are utilized to cover the manhole of a tanker trailer or railcar when filling the tanker with the desired cargo. Commonly transported liquid cargo may be volatile and/or hazardous, such as liquid propane, gasoline, oil, liquefied natural gas, asphalt, industrial chemicals or acids. Other liquid cargo may not be hazardous, but may require maintaining sanitary conditions, such as milk, vegetable oils, other food oils, juices, or other items. Further, many dry goods which are commonly transported in such tankers may create a fine dust which may cause respiratory problems for workers when filling the tanks up with the dry cargo. A vapor plate plays an important role in keeping the volatile or hazardous gases in the tank or, alternatively, the un-sanitized airborne contaminants out. 
         [0006]    Particularly, as used in the petroleum and chemical industries, the vapor plate keeps the gasoline or chemical vapors within the tank and may also prevent the build-up of excess vapor by allowing vapor removal using a vapor recovery system. Keeping the vapor from escaping the tank through the vapor plate is important for at least the following reasons: (1) the health of the operator, (2) environmental protection, (3) general safety (for example preventing build-up of flammable gases), and (4) satisfying industrial or governmental regulations. In other industries, vapor plates may also be important for protecting the safety of the food supply. 
         [0007]    However, given the importance of keeping vapors in or contaminants out of the tanker in view of the harmful effects listed above, existing vapor plates have continually been found to perform insufficiently over their functioning lives. Existing vapor plates can generally comprise a plate having threaded rods extending through which are threadably engaged to the plate. The threaded rods generally have an appendage at the bottom of the threaded rod that can be raised and lowered to engage and release the appendage against the bottom of a rim of a manhole on a tank trailer or railcar. The appendage is raised and lowered by a user generally turning a handle at the top of the threaded rod and adjusting a threaded collar. 
         [0008]    Threaded rods can be made of softer steel than many other steel components in order to economically manufacture a tooled threaded rod. The softer material can result in the threaded rod bending at some point during its functional life, particularly early on. Any bending of the threaded rod negatively impacts the function and performance of the vapor plate. The threaded push rod also has other shortcomings. As the threaded rod repeatedly passes through the threads in the existing vapor plate, any protective coating on the material wears off resulting in corrosion of the threads which results in the loss of material. In addition, if the collar is even a slightly different steel grade than the threaded rod, with either a higher or lower strength, the threads in the collar or on the threaded rod can wear down, again resulting in a loss of material. Further, the bending of the rod alters the thread distance at the bend. These frequently occurring losses of material or changes in the thread distance can create a passageway for vapors or gas to leak through the threads and vapor plate out of, or into, the tank. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention is directed to a vapor plate for covering a manhole of a cargo transport tanker while the tank is being filled. The vapor plate comprises a plate member and a plurality of push rod assemblies operably connected to the plate member. The plate member may have a sealing member adhered to a portion thereof Each of said plurality of push rod assemblies includes a guide tube extending through said plate member and coupled thereto, a push rod journaled for linear and rotational travel within said guide tube, and a resistance mechanism coupled to the push rod. Each push rod includes handles coupled to a respective end of a rod of said push rod. The resistance mechanism includes a spring and a collar. The guide tube includes a tube, an upper ring plate at one end of the tube and a lower ring plate at another end of the tube. 
         [0010]    The spring is positioned between said collar and said upper ring plate. A position of said collar is adjustable along a length of said rod of said push rod. The collar is fixed along the rod to a selected position such that the spring resists linear travel of said push rod relative to said guide tube. O-rings are positioned within said upper and lower ring plates of said guide tube to engage said rod thereby forming a substantially gas-resistant seal between said guide tube and said rod of said push rod. 
         [0011]    In use, the vapor plate is used to seal a manhole of a cargo tanker while filling the tanker carrying liquid or dry cargo. In one embodiment, to install the vapor plate on the manhole, top handles of the push rods are rotated so the handle extends radially inward. Since the lower handle is timed with said top handle, rotating the top handle results in both handles facing radially inward. The vapor plate may be then placed on top of a rim of the manhole of the tanker because the lower handles are turned inward and will not catch on the top of the manhole rim. Next the top handle of the push rod is rotated so that the top and lower handles extend radially outward so that the lower handle extends radially further outward than the bottom edge of the manhole rim. Next, the top handle is pulled upward until the lower handle locates and contacts with the bottom edge of the manhole rim. Next, the top handle is again rotated so that the lower handle points radially inward and is no longer is in contact with the bottom edge of the manhole rim. The top handle is pulled slightly upward a distance to position the lower handle a distance above the bottom edge of the bottom edge of the manhole rim. Next, the collar is locked and fixed in position on the rod. The collar is fixed on the rod so that the collar bears against the spring. The spring also bears against the guide tube. The process is repeated for all push rod assemblies. 
         [0012]    A user then applies a substantially linearly downward force on the top handle of the push rod until the lower handle is below the bottom edge of the rim. The user again rotates the top handle so that the lower handle extends substantially radially outward and under the rim of the manhole. Once the lower handle is in place, the user gradually reduces the downward force applied on the top handle until said lower handle contacts said bottom edge of said rim. The user then stops applying the downward force resulting in the manhole rim being clamped between the plate and the lower handle of the vapor plate with the resistance force generated by the displacement of the collar against the spring. The process is repeated for all push rod assemblies 
         [0013]    Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments and the accompanying drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0014]    The accompanying drawings form a part of the specification and are to be read in conjunction therewith. 
           [0015]      FIG. 1  is a schematic perspective view of one embodiment of a vapor plate in accordance with the teachings of the present invention installed on a manhole of a tanker; 
           [0016]      FIG. 2   a  is a side view of one embodiment of the vapor plate shown in  FIG. 1  taken along view lines A-A in accordance with the teachings of the present invention; in contrast to  FIG. 1 , the handles of the push rods are shown as rotated inward which is where they are located when the vapor plate is initially set on the manhole but prior to being installed; set screws intentionally omitted from  FIG. 1  are shown in  FIG. 2   a  to further illustrate the invention; the manhole and tanker shown in  FIG. 1  have been intentionally omitted from  FIG. 2   a;    
           [0017]      FIG. 2   b  is a close up of an alternative of a type of upper handle used with a rod of a push rod of the present invention: 
           [0018]      FIG. 3  is a cross-sectional view of the guide tube and push rod assembly of the embodiment of the present vapor plate of  FIG. 2   a  along the line  3 - 3 ; 
           [0019]      FIG. 4  is a cross-sectional view of the embodiment of the present vapor plate of  FIG. 1  taken along a view line similar to view line A-A; the view line has been modified to section through the guide tubes and resistance mechanisms shown in  FIG. 1  which are the same as those shown in  FIG. 2   a  accept the set screws are intentionally omitted from the section; the handles of the push rods, like in  FIG. 2   a  are shown as rotated inward which is where they are located when the vapor plate is initially set on the manhole but prior to being installed; and 
           [0020]      FIG. 5  is the cross-sectional view shown in  FIG. 4  at another point during the installation process. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    The following detailed description of the present invention references the accompanying drawing figures that illustrate specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the present invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the spirit and scope of the present invention. The present invention is defined by the appended claims and, therefore, the description is not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled. 
         [0022]    As illustrated in  FIG. 1 , the present invention is directed toward a vapor plate  10  having an improved mechanism for coupling vapor plate  10  to a manhole  202  of a fluid or dry goods transport tanker  200  such as an over-the-road or railroad tanker to transport liquid or dry cargo. Examples of liquid cargo include gasoline, oil, asphalt, chemicals, acids, milk, other food products, or any other liquid now known or hereafter known to be conveyed using bulk transport tankers. Examples of dry cargo includes grain, grain flour, chemical granules, powdered milk, or any other dry cargo now known or hereafter known to be conveyed using bulk transport tankers. Vapor plate  10  includes a plate  24 , guide tubes  12 , push rods  14  passing through said plate  24 , resistance mechanisms  52  coupled to push rods  14 , at least one handle  16  coupled to plate  24 , and a cargo passage  18  through said plate  24 . A portion  22 ′ of a loading arm, which can also be called a supply pipe, passes through the hole  18 . Also a portion of the loading arm  22 ″ is above plate  24  and includes a flange or coupling, in the form of a flange or collar  22 ′″. The loading arm portion, by way of the flange  22 ′″, is fixedly coupled to a part of the plate  24  adjacent the wall  24 ′ forming the passage  18 . The portions of the loading arm  22 ′,  22 ″, and  22 ′″ can be called a loading arm coupling or supply pipe coupling. The loading arm coupling can be continuous with and an integral part of the loading arm portion upstream of the loading aim coupling. It can also be a separate piece which couples to another upstream portion of the loading arm. When the vapor plate  10  is installed on the tank  200 , the cargo is discharged from the loading arm portion  22 ′ extending through the plate  24  and into tank  200 . The cargo passes through hole  18 . Flange  22 ′″ may be welded to plate  24 . Alternatively, flange bolts (not shown) may be welded to the top of plate  24  and the flange may be connected to plate  24  by these bolts. These alternatives are used so that there are no mounting holes through plate  24  which provide the opportunity for vapor to escape. However, any method of coupling a loading arm, which can also be called a supply pipe, to vapor plate now known or hereafter developed may be utilized. Vapor plate  10  may also include a vapor recovery opening  20  through plate  24 . A vapor recovery assembly to remove any harmful vapor build-up in the tanker while filling the tanker  200  could then be connected to the plate  24  at opening  20 . 
         [0023]      FIG. 2   a  illustrates a side sectional view of vapor plate  10 . Vapor plate  10  has plate  24  and sealing member  26 . Sealing member  26  can be considered a component of plate  24 . Plate  24  may be any thickness known in the art. However, plate  24  is preferably in a range depending on the application. For instance, between one-eighth and one inch (⅛″-1″), for some applications is acceptable. Plate  24  may be steel, aluminum, or any other material now known or hereafter developed. Handle  16  is coupled to plate  24  using any method now known or hereafter developed. However, handle  16  is preferably welded so as to not introduce any additional holes through plate  24 . Sealing member  26  is adhered to a bottom surface of plate  24  and may be elastic or a viscoelastic material such as neoprene, closed cell foam, rubber, polymer, or any other material now known or hereafter developed. 
         [0024]      FIG. 2   a  further shows guide tubes  12 . Each guide tube  12  comprises pipe or tube sections  28 , upper ring plates  30 , and lower ring plates  32 , wherein the upper and lower ring plates  30  and  32  of each tube  12  may be coupled to each tube&#39;s respective pipe section  28 . The pipe section can also be called a tube section or tube or pipe  28 . Any mechanical or chemical coupling method now known or hereafter developed may be utilized, including threaded connection, welding, adhesives, or a mechanical fastener to couple each tube  28  to its respective upper  30  and lower  32  ring plates. The guide tubes  12  are each the same. 
         [0025]      FIG. 3  is a sectional view through one of the guide tubes  12  that illustrates lower ring plate  32  and upper ring plate  30 . The lower ring plate  32  includes a bushing  34  housed in a hollow portion of the plate. The bushing can be made of metal such as steel or brass. The bushing  34  includes grooves  37  each which house an O-ring  38 . As further shown in  FIG. 3 , upper ring plate  30  comprises a bushing  36  housed in a hollow portion of the ring plate  30 . The bushing includes grooves  37 ′, each housing at least one O-ring  38 ′. The constructions of ring plates  30 ,  32  seal out vapors from entering or escaping through guide tubes  12 . The bushings  34 ,  36  may be sleeve bearings with grooves  37 ,  37 ′ and O-rings  38 ,  38 ′. Further, guide tube  12  may include a wiper  40  disposed in one or more of ring plate  30  and  32  as shown in  FIG. 3 . The wiper  40  can be considered a component of its respective ring plate  30 ,  32 . Guide tube  12  and its components may be any material including steel, aluminum, brass, carbon fiber, polymer, any combination thereof, or any other now known or hereafter developed. Each tube  12  extends through a respective hole of the plate  24  and is fixed and connected to a respective portion of plate  24 . In more detail, the pipes  28  of guide tubes  12  each extend through one of the respective holes of plate  12 . Each pipe  28  is fixed to the plate. A weld normally fixes each pipe  28  to the plate  24 . 
         [0026]    In  FIG. 2   a , push rods  14  are shown.  FIG. 2   a  shows two push rods  14 . Each push rod  14  includes a rod  42 , a top handle  44 , and a lower handle  46 . Rod  42  may be any length which provides the necessary adjustment to be used in a variety of manholes. For example, manhole  202  may have a rim  204  of various heights or axial lengths. Accordingly, a push rod  14  may have a length of rod  42  for use with one particular height of rim  204  if one certain type of tank is continually used. However, vapor plate  10  will have the widest application if rod  42  has a length that can accommodate rims  204  of varying and commonly experienced heights. Each end of rod  42  is coupled to handle  44  and  46 , respectively, using any coupling method known in the art wherein the handles  44  and  46  are timed. Having timed handles means that the handles  44 ,  46  coupled to a rod  42  face in the same direction, preferably the exact same direction, at all times as shown. Each handle  44  and  46  may be secured in this “timed” position using a pin  48 . In one embodiment, each end of rod  42  is threaded to respective handles  44  and  46 . Each handle has a threaded socket to receive the respective end of rod  42  for coupling handles  44  and  46  to rod  42 . 
         [0027]    Handles  44  and  46  may extend in one direction away from rod  42 . Alternatively, one embodiment of top handle  44   a  shown in  FIG. 2   b  includes a “T” handle, wherein handle  44   a  would include an indicator  50 , such as the arrow shown, to indicate to a user the direction in which the timed lower handle  46  points. Lower handle  46  may include a friction-increasing material (not shown), such as rubber or a viscoelastic polymer, disposed on the face that engages rim  204 . 
         [0028]    As shown in  FIG. 2   a , resistance mechanisms  52 ,  52 ′ provide a resistance and clamping force. The mechanisms  52 ,  52 ′ resist the linear translation of push rod  14  relative to guide tube  12  when resistance mechanisms  52 ,  52 ′ are fixed at a position along the length of the rods  42 . One embodiment of resistance mechanism  52  shown with rod  14  on the left of the page includes a bearing collar  54 , a spring  56 , a handle nut  58 , a first collar  60 , and a second collar  62  wherein first collar  60  and second collar  62  may be secured to rod  42  at a position along its length using a set screw  64 . Bearing collar  54  can also have a set screw  64 . An alternative resistance mechanism  52 ′ is shown in  FIG. 2   a  on the right of the page with rod  14 . The mechanism  52 ′ includes a clamp  66  in place of the first and second collars  60 ,  62 . Clamp  66  may be any pipe clamp now known or hereafter developed including a slide clamp, a cam clamp, a quick-release pipe clamp, or any other known pipe clamp. In the embodiment shown, the clamp  66  operates by pulling an upper portion  68  away from a lower portion  70  which disengages the circumferential clamping force applied to the rod and allows the position of clamp  66  to be adjusted along the length of rod  42 . Clamp  66  may include a contact material configured to contact the surface of rod  42  to increase the frictional force provided to resist movement of clamp  66  relative to rod  42  as known in the art. 
         [0029]    Push rods  14  and their components may be constructed from any material including steel, aluminum, brass, carbon fiber, or polymer or any other material now known or hereafter developed. One embodiment includes rod  42  being 1144 carbon steel that is chromed for surface protection and/or reduction of friction. 
         [0030]    Spring  56  of mechanisms  52 ,  52 ′ is operable to exert an upward  100  force on rod  42  when collars  60  and  62  or clamp  66  are fixed to rod  42  and a user applies a downward  102  force on push rod  14  compressing spring  56  against guide tube  12 . Spring  56  may be any type of spring now known or hereafter developed including viscoelastic or elastic bands or bushings or any other compression resistance spring now known or hereafter developed. Upward is in a direction  100  away from and out the manhole  202 . Downward  102  is in a direction into the manhole  202  of tank  200 . 
         [0031]    One beneficial feature of the present vapor plate  10  is that it is configured to significantly reduce the amount of vapor that escapes through the openings in plate  24  that accommodate the passage of push rods  14  and guide tubes  12 . This beneficial configuration of the push rods  14  and guide tubes  12  in the present vapor plate  10  is best illustrated in  FIG. 3 .  FIG. 3  shows a push rod  14 . As shown, rod  42  of push rod  14  passes through upper ring plate  30 , pipe section  28 , and lower ring plate  32  of guide tube  12 . Rod  42  passes through upper wiper  40  housed in upper ring plate  30  wherein wiper  40  is an elastic rubber or polymer ring which constricts slightly around rod  42  to prevent debris from entering into guide tube  12  and interfering with the movement of rod  42  relative to guide tube  12 . Wiper  40  does not impede rod  42  from rotating or linearly translating within guide tube  12 . Upper ring plate  30  may also include bushing  36  which includes one or more grooves  37 ′ housing one or more O-rings  38 ′ as shown. O-rings  38 ′ are generally rubber or another smooth viscoelastic polymer which again allow rod  42  to rotate or linearly translate within guide tube  12 , but create a substantially liquid and/or gas-resistant seal between rod  42  and guide tube  12  thereby substantially preventing vapor from passing through guide tube  12  into or out of tank  200 . 
         [0032]    The space between rod  42  and pipe section  28  may be empty or may be packed with grease or other lubricant to facilitate the movement of rod  42  therewithin. Rod  42  also passes through a bottom end of pipe section  28  and lower ring plate  32 . Lower ring plate  32  may include bushing  34  inserted therein. Wherein rod  42  is inserted through bushing  34  such that bushing  34  allows linear and rotational displacement of rod  42  in relation to lower ring plate  32 . Bushing  34  may also be configured to provide a liquid or gas-resistant seal as known in the art such as grooves  37  and O-rings  38  which are the same or different from grooves  37 ′ and O-rings  38 ′. As further shown in  FIG. 3 , rod  42  extends through a lower wiper  40  which is the same as upper wiper  40  and also helps prevent debris from entering the guide tube  12  and interfering with the movement of rod  42  therein. 
         [0033]    In the embodiment illustrated in  FIG. 1 , vapor plate  10  includes four guide tubes  12  and push rods  14  to secure it to a manhole  202 . The resistance mechanisms  52 ,  52 ′ could all have the same construction. Alternatively some of the mechanisms can have the construction of mechanism  52  and some the construction of mechanism  52 ′. A guide tube  12  combined with a push rod  14  and a resistance mechanism  52 ,  52 ′ can be called a push rod assembly. Depending upon the size of the manhole  202 , vapor plate  10  may include any number of guide tubes  12  and push rods  14  as necessary to secure vapor plate  10  to rim  204  of manhole  202  and provide the adequate clamping force to hold vapor pate  10  in place on rim  204 . Further, the spacing of guide tubes  12  and push rods  14  should be sufficient such that plate  24  of a known thickness does not bend between the supports provided by the guide tubes  12  and push rods  14 . The determination of the necessary spacing is well known to a person of skill in the art. 
         [0034]    In use, an embodiment of vapor plate  10  is inserted into manhole  202  of tank  200  such that plate  24  of vapor plate  10  bears on a top edge  208  of manhole rim  204 . The portion of plate  24  that bears upon rim  205  is seal  26 . As shown in  FIG. 4 , to facilitate inserting the components of vapor plate  10  into the manhole  202 , top handle  44  and lower handle  46  of push rods  14  are turned inwardly. Inwardly is relative to the central axis or portion  106  of plate  24 . Inward is more toward the central portion  106  than away from the central portion. When moved inwardly, the push rods  14  can be generally in a linear position below plate  24  such that lower handle  46  will be below a bottom edge  206  of rim  204 . As shown, sealing member  26  generally deforms under the weight of vapor plate  10  when plate  24  is set upon top edge  208  rim  204  of manhole  202 . The deformation of sealing member  26  may create a substantially liquid or gas-tight seal between manhole rim  204  and plate  24 . After the inward handles are below bottom edge  206 , a user next rotates each top handle  44  until it points substantially radially outward from a center or axis  106  of plate  24 . A user then pulls a handle  44  upwardly in direction  100  so that rod  42  linearly translates, along its longitudinal axis, with respect to guide tube  12  and thereby draws lower handle  46  into contact with bottom edge  206  of rim  204  as shown in dashed lines in  FIG. 5 . This step allows a user to locate bottom edge  206  of rim  204 . Outwardly is relative to the central axis or portion  106  of plate  24 . Outward is more away from the central portion  106  than toward the central portion. A user may have to release collars  60  and  62  or clamp  66  during one or more of the above rotating or sliding steps above as needed to allow rod  42  to slide relative thereto depending upon the type of collars or clamps being used. 
         [0035]    Now further referring to  FIG. 5 , illustrations of the next step of installation are provided. Once the user has located bottom edge  206  of rim  204 , the user again turns top handle  44  of the rod  14  so that lower handle  46  of rod  14  is pointed inwardly toward center portion  106 . The user displaces push rod  14  upward in direction  100  a distance A by moving top handle  44  of rod in an upward direction  100 . Once a rod  14  is at this point, the user fixes the position of first and second collars  60  and  62  with respect to rod  42  of push rod  14 , if mechanism  52  is involved, by tightening set screws  64 . If mechanism  52 ′ is involved, the user fixes the position of clamp  66  relative to rod  42  of push rod  14  by clamping clamp  66  in a fixed position. The collars or clamps are thus fixed with respect to rod  142  so the rod does not move relative to its respective collar or clamp. The collars  60  and  62  or clamp  66  should be resting against their respective spring  56  when fixed in position on rod  42 . If a handle nut  58  or the like is used than they should be resting against member  58  which in turn rests against spring  56 . Thus, any displacement of the push rod  14  downward in direction  102  encounters a resistance force in direction  100  from spring  56  of resistance mechanism  52 ,  52 ′. For example, applying a downward force to handle  44  would engage collars  60  and  62  against spring  56  and any displacement of spring  56  downward in direction  102  results in the spring applying an upward resistance force in direction  100 . In one embodiment, spring  56  of resistance element  52  provides a resistance force of around seventy pounds per inch of displacement. The above procedure is repeated for every push rod assembly so the lower handles  46  of each rod  14  are set to the distance above the bottom edge  206  of rim  204 . 
         [0036]    Having set collars  60 ,  62  or clamp  66  of the push rods  14 , next, as shown in  FIG. 5 , the user will push down on a handle  44  against the resistance of a spring  56  of resistance mechanisms  52 ,  52 ′ such that lower handle  46  of a rod  14  is again below bottom edge  206  of rim  204 . At this time, the user rotates top handle  44  while maintaining the downward force applied thereto so that handle  44  again points substantially radially outward from center  106 . This motion also orients lower handle  46  to also point substantially radially outward. The user then releases the downward force on handle  44 . As a result of the release, resistance element  52 ,  52 ′ by way of spring  56 , pushes and moves push rod  14  upwardly such that lower handle  46  engages bottom edge  206  of rim  204  as shown. The engagement applies a compressive force between lower handle  46  and sealing member  26  of plate  24 . The above process is repeated for all push rod assemblies coupled to the plate  24 . The plate  24  is compressed against top edge  208  of rim  204  thereby securing vapor plate  10  to manhole  202 . The clamping force applied may result in additional displacement of sealing member  26  adding to or perfecting the vapor-resistant seal. 
         [0037]    The clamping force applied is substantially equal to the resistance force multiplied by the displacement distance Δ. For example if Δ equals two inches and the resistance force equals seventy pounds per inch, then the force applied to displace push rod  14  such that the lower handle  46  is below rim  204  is at least one-hundred forty (140) pounds. Similarly, the clamping force applied by the resistance mechanism  52  which effectively clamps the rim between plate  24  and handle  46  is also one-hundred forty (140) pounds. Thus, the clamping force applied can be easily adjusted by a user by increasing or decreasing Δ, and/or using springs  56  with a higher or lower spring resistance force. 
         [0038]    Vapor plate  10  can be removed simply by pushing down on each push rod  14 . Pushing down on the rods disengages the lower handles  46  from rim  204 . The handle  44  is then turned radially inward toward axis  106 . Further, the removal process may be shortened in some embodiments by simply disengaging the resistance mechanism  52  by untightening the set screws  64  of collars  60  and  62 , or releasing clamp  66  from rod  42  so that the resistance mechanism  52 ′ no longer exerts any force upon push rod  14 . 
         [0039]    As is evident from the foregoing description, certain aspects of the present invention are not limited to the particular details of the examples illustrated herein. It is therefore contemplated that other modifications and applications using other similar or related features or techniques will occur to those skilled in the art. It is accordingly intended that all such modifications, variations, and other uses and applications which do not depart from the spirit and scope of the present invention are deemed to be covered by the present invention. 
         [0040]    Other aspects, objects, and advantages of the present invention can be obtained from a study of the drawings, the disclosures, and the appended claims.