Abstract:
A head for use in a combination float and maximum liquid level gauge. The head has a receptacle for receiving the support member of a float gauge and contains a passageway one end of which is positioned so that it will be exposed to the interior of a LP gas vessel and the other end of a passageway is external of the LP gas container. The exterior end is closed by a valve. The head may be used in conjunction with a dip tube, a float gauge, or a float gauge which has been modified to function as a dip tube to provide a combination fixed liquid level and float gauge.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to the gauges and in particular gauges for measuring the liquid level of liquefied petroleum gases. 
     BACKGROUND OF THE INVENTION 
     As used herein, liquefied petroleum gas (LP gas) refers to either the liquid or vapor state. LP gas is pressurized and stored in a pressure container. The more specific terms of “liquid LP gas” will refer to the pressurized gases in the liquid state and the term “vapor LP gas” will refer to the vapor phase of such gases. Because the volume of the liquefied gas varies with atmospheric temperature, it is important that the volume of the liquefied gas not be equal to the volume of the storage container otherwise there is a risk of bursting the storage container. Thus a filled container represents a maximum safe volume of liquid LP gas over which is a pressurized vapor LP gas. The liquid level of the liquid LP gas is measured typically by a float gauge. The level of liquid LP gas in the container can also be measured with a fixed liquid level gauge. A fixed liquid level gauge uses a dip tube and a relatively small positive shutoff valve and is designed to indicate when the liquid level in the container being filled reaches a point at which the dip tube communicates with the interior of the container. More typically a fixed maximum liquid level gauge is employed which it is set by proper dip tube length to the liquid level at which a container is filled to its maximum permitted filling limit under applicable safety guidelines. The fixed liquid level gauge allows pressurized vapor LP gas to be expelled through the gauge while the liquid level is below the dip tube as the tank is being filled. When the liquid level reaches the lower end of the dip tube, liquid begins to be expelled from the gauge, and the condensation of water vapor in the air can be seen enunciating that liquid has risen to the height indicated by the fixed liquid gauge. 
     Float gauges typically are constructed such that a float is positioned inside the container which rests on the liquid surface and the position of the float is transmitted through a lever mechanism and linkages to a pointer and dial outside the container. The motion of the float is conveyed to the gauge typically by magnetic linkage through a non-magnetic plate so that no LP gas is released to the atmosphere. The filling operation and the limit of fill is controlled by the weight of liquid LP gas or some prefer to utilize the fixed maximum liquid level gauge in order to ensure that the maximum safe permissible volume is not exceeded when the container is filled. Employment of both a float actuated contents gauge or the fixed liquid level gauge in the past required two openings in the container. There has been a need to minimize the number of openings required in a container and to simplify design and manufacturing costs, the present invention has the advantages requiring only one opening in the container for both gauges, simplifies construction and reduces the number of parts required while still providing both a float contents gauge and a fixed maximum liquid level gauge. 
     SUMMARY OF THE INVENTION 
     One object of the invention is to provide a gauge head configured to serve both as a head for a float gauge and for a fixed liquid level gauge. In one aspect, the invention is a body having a top and bottom with a passageway passing through the body having a first end and a second end and the body defines a receptacle to receive the end of a float support member. In the preferred embodiment the first end of said passageway is adapted to receive a dip tube for the maximum liquid level gauge and a valve is positioned at the second end of said passageway. In a preferred embodiment the body also includes a recess on the top surface to receive a dial assembly adapted to magnetically link with the magnet on a float arm assembly. In the preferred embodiment, the gauge is designed to be mounted on the top of the pressure vessel. 
     Another object of the invention is to provide for a simplified construction in which a separate dip tube for the maximum liquid level gauge is not required. In this embodiment, the invention has a gauge head for a float and fixed liquid level gauge comprising of body having a top and bottom, the body defines a receptacle for receiving a float support member of a float arm assembly and also defines a passageway having a first and second end, said first end communicating with the receptacle for the tubular member of the float arm assembly. The second end of the passageway is adapted to receive a valve. 
     In another aspect, the present invention is a combined float and fixed maximum liquid level gauge head comprising a body having a top and bottom and defining a receptacle for the float support and defining a passageway having a first and second end said first end communicating with the receptacle for the float support member and said second end adapted to receive a valve. The float support member defines a passageway and when attached to the receptacle extends from the bottom of the head, said support member&#39;s passageway communicates with the passageway in said head to form an extended passageway by joining the passageways. In another embodiment the support member is the length of a maximum filled dip tube. In another embodiment the support member is supplied with an orifice at a distance from the head where a maximum filled dip tube would be. 
     In another aspect, the present invention relates to a complete gauge having both a fixed liquid level and float gauge. The gauge is formed from one of the heads described above with the attachment of a dip tube and float gauge components having a top and bottom with a bushing at the top and a bushing at the bottom to hold rotatably a shaft having a magnet there. The shaft has a top and bottom. The top being equipped with a magnet and the bottom with a gear to engage a gear assembly attached to the float arm. 
     Movement of the float causes the float arm to move, rotating the shaft and the attached magnet. The magnet on the shaft is magnetically linked with a magnet in the dial assembly. Rotation of the magnet on the shaft rotates the magnets in the dial assembly causing the pointer to move. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further objects and advantages of the invention will become more apparent from the following description in claims and from the accompanying drawings wherein: 
     FIG. 1 is a cross sectional view of one embodiment head of the present invention. 
     FIG. 2 is a cross sectional view of a dip tube to be attached to the apparatus of FIG.  1 . 
     FIG. 3 is a partial cross sectional view of the head, of figure to be used to produce another embodiment of the invention. 
     FIG. 4 is a top view of the dial assembly. 
     FIG. 5 is another embodiment of the present invention in partial cross section. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference now to the figures, and in particular to FIG. 1 a head  10  useful for a combination float and fixed liquid level gauge is shown. Head  10  is formed by a body  12  which has a top  14  and a top portion generally indicated by T and a bottom  16  and a bottom portion generally indicated by B. In the illustrated embodiment the head  10  is shown attached to a vessel  18  shown in phantom. The top portion of the gauge refers to that portion which extends outside of the vessel and the bottom portion is that portion which engages the vessel and which may extend into the vessel as illustrated. In the illustrated embodiment, the bottom surface has threads  20  to engage corresponding threads on the vessel  18 . Other means to attach the gauge to the vessel may be used. The body  12  defines a passageway  22  which has a first end  24  and a second end  26 . The first end  24  is used to communicate with the vessel through the bottom of the body and the second end  26  extends to the outside of the vessel. As illustrated in the FIG. 1, a valve  28  is located at the second end  26  of the passageway  22 . Any suitable valve may be used, however, as illustrated a needle valve  28  can be employed. The needle valve  28  comprises a threaded plug with a valve passageway  30  therethrough and has a tip  32  which engages a reduced diameter portion of the passageway  22  to close the passageway  22 . When the valve  28  is fully screwed in the tip  32  seals the passageway  22  preventing the escape of LP gas. The valve  28  is opened by turning the valve such that the seal by the tip  32  and mating surface is broken and hereby allows LP gas to fill the space  34  between the valve tip  32  and the passageway  22  allowing LP gas to escape through valve passageway  30 . The body  12  also defines a receptacle  36  for receiving float support member (not shown in FIG.  1 ). In the illustrated embodiment the receptacle  36  is a cylindrical opening which at its closed end  38  has a tapering surface  40  reducing the diameter of the opening  42 . The float support member may be press fitted into the opening. Other means of attaching the float support member to the head  10  such as threads can be utilized. However, press fitting has been found to be durable, easy to manufacture and economical. In a preferred embodiment, the top surface also defines a dial recess assembly  44 . Recess  44  allows for the proper orientation of the dial assembly with the other components of the gauge. In this embodiment, the length of the bottom portion which extends into the tank may be predetermined length of a fixed maximum liquid level gauge. Alternatively, as shown in FIG. 2 a dip tube  50  may be attached to the head  10  by any suitable means such as threads  52  or by pressed fitting. In the illustrated embodiment the dip tube  50  can be screwed into threads  54  at the first end  24  of passageway  22 . This is a preferred construction because the length of dip tube  50  can be changed for different styles and sizes of vessels as is known in the art to provide a fixed maximum level gauge for a variety of vessels while using the same head  10 . 
     FIG. 3 is a partial cross sectional view of a combination gauge  60  using body  12 , having dip tube  50  attached, a dial assembly  62  located in recess  44 , and a float support member  64  positioned in receptacle  36 . Like numbers in the drawings refer to like items. 
     The float support member  62  has a bushing  66  which holds shaft  68  in place such that it may rotate. Shaft  68  is linked to the float, now shown. The end of the shaft  68  carries a magnet  69 . Magnet  69  in combination with magnet  70  in the dial assembly magnetically couples the movement of shaft  68  with the dial pointer  72 . The pointer  72  is pivotally mounted in pivot pin  74  extending from the base  76  of the dial assembly  62 . The pointer  72  moves over dial face  77  which has indicia  78  as shown in FIG. 4 indicating fluid level. 
     A fixed maximum liquid gauge indicates a liquid level at which the vessel is filled to its maximum permitted limit. In operation of these maximum level gauges, the valve is opened while the vessel is being filled. The discharge from the maximum liquid level gauge at the valve is invisible if vapor LP gas is being emitted. As a level of the liquid LP gas reaches the bottom of the dip tube the discharge from the valve fogs by the condensation of water vapor in the air created by refrigeration when the vaporizing liquid is discharged through the valve. The length of the dip tube is determined by means and methods known in the art. The length of the dip tube may vary depending upon the type of gas, the volume of the vessel and the configuration of the container. When a fog is created by the discharge from the maximum liquid level gauge, the operator knows to discontinue filling of the vessel. 
     In another embodiment of the present invention, the need for a dip tube or to have the body extend into the tank the length of a dip tube is eliminated by using the float support member, in a manner in which it functions as the dip tube as described below. 
     FIG. 5 shows a head  80  comprised of a body  82  having a top portion T and a bottom portion B and defining a receptacle  84  for a float support member  86 . The support member  86  can be of any particular useful shape however a tubular member is preferred. The body  82  also defines a passageway  88  having a first end  90  and second end  92 . The first end  90  communicates with the receptacle  84  for the support member  86  and the second end  92  communicates with the outer surface of the top portion of the body  82 . As in the other embodiment, the second end  92  of the passageway  88  has a valve  94  attached thereto. The valve  94  can be of any suitable construction such as the needle valve  28  described with reference to FIGS. 5 and 1. The valve  94  is a nut having a passageway  96  and operated in the manner as described about in reference to FIGS. 1-3. In the preferred embodiment, the body  82  also includes a recess  98  for a proper placement of the dial assembly (not shown). The support member  86  defines a passageway  87 . 
     The float assembly structured  100  includes a support member  86  that extends from the head  82  and into the vessel  102  shown in phantom. An arm  104  is mounted at a pivot  106  along its length for a pivotal motion about axis  108 . A gear  110  is mounted on the arm  104  for movement with the arm  104 . The first end of the arm  104  mounts a float  112  which is so configured to float at the surface  114  of the liquid in the vessel. A counter weight  116  can be mounted at the opposite end of the arm  104 . The gear  110  meshes with gear  118  mounted on the bottom end  120  of a shaft  122  extending within support member  86  attached to the head  82 . Shaft  122  can be rotatably held by bushings  140  and  144  or other suitable structures at the top and bottom of support member  86  such that shaft  122  may rotate. Within the recess  98  of the head a dial assembly can be mounted (not shown). The end top  124  of shaft  86  carries a magnet  126  which is positioned proximate to the dial assembly. In operation the pivot arm  104  pivots about axis  108  as float  112  follows the level  114  of the fluid. The pivotal motion of the arm  104  causes gear  110  to rotate gear  118  and thereby causing shaft  122  to rotate magnet  126  about an axis  108 . Magnet  126  serves as a coupler to transmit movement of the float  112  to the dial assembly. For ease of reference, the dial assembly can operate in the same fashion as discussed above in reference to FIG.  3 . The dial assembly  62  has a base  76  which is provided with pivot pin  74 . The pointer  72  pivots or rotates about the axis of the pivot pin  74 . On the bottom of the pointer  72  is a magnet  70 . The magnet  70  is secured to the pointer  72  and serves as a coupler by interacting with magnet  126  so that the position the pointer  72  about the axis correlates directly with the position of float  112  and thus the surface  114  of the fluid. 
     The face plate  76 , provides a surface which includes indicia  78  to give a read out of level of fluid in the vessel. A transparent cover  79  is provided on the top of the pointer assembly  62 . Such pointer assemblies are well known in the art, and variations of such pointers are also well known in the art and can be utilized, further the pointer assembly can also be of the type that produces a digital readout. 
     The operation of the float gauge aspect of the combined gauge has been described. The operation of the fixed maximum liquid level gauge in this embodiment will now be described. Shaft  122  rotates within bushings  140  and  144 . The space between the bushings and the shaft can allow the passage of LP gas between the shaft and the bushing. Also, if desired, orifices  146  and  148  may be provided in the bushings to facilitate passage of LP gas within the support member  86 . Thus, the construction of the gauge allows the support member  86  to be utilized as the dip tube as well as the support member for the float mechanism. In one embodiment, the float support member  86  can be made of the length of an appropriate dip tube for the vessel in question. Thus, vapor LP gas can enter the open end of  150  of support  86  and flow into passageway  87 , pass the bushings  144  and  140 , flow into the first end  90  of the passageway  88  and then be discharged through passageway  96  of valve  94  when the valve  94  is opened. In the same manner, orifices  148  and  146  may be used to permit free flow of LP gas through passageway  87  of the support member  86 . Thus, passageway  88  and the passageway of support  86  form the maximum liquid level gauge. As described up above, when the liquid reaches the opening  150  it will result in liquid LP gas exiting the valve and condensation at the valve will indicate the liquid has reached the maximum fill position. Alternatively, an aperture  152  can be provided in support member  86  which communicates with passageway  87 . The aperture  152  is positioned along support member  86  at the length that a fixed dip tube would extend. When the aperture is placed above opening  150  the aperture will be placed at the location of the maximum fill level and the portion of the support  86  extending from the body to the aperture will serve as a dip tube. The condensate will not be admitted at valve  92  until the liquid LP gas level reaches aperture  152 . This embodiment allows a single support member to be used for a number of different vessels because aperture  152  can be drilled in support  86  at a location corresponding to the maximum liquid level of different styles and sizes of vessels. 
     The head for the gauge is preferably made out of zinc or other non-magnetic materials so as not to interfere with a magnetic coupling of the float arm magnet with the dial assembly magnet. Other materials of construction as known in the art. Other materials as is known in the art may be employed. 
     While certain embodiments of the present invention have been illustrated in the drawings, and described in the foregoing detailed description, it will be understood that the invention is not limited to the embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions of parts and elements without departing from the scope and spirit of the invention.