Abstract:
A gas flowmeter and associated method of forming a glass flowmeter includes a body having a passage that communicates with an inlet and an outlet for receiving gas flow therethrough. A selectively variable valve controls a flow of gas to the outlet, and plural calibrated scales are operatively associated with the passage to represent a flow rate of gas through the passage. First and second floats having different material properties are received in the passage and are viewable in operative association with the calibrated scales.

Description:
[0001]    This application claims the priority benefit of U.S. provisional application Ser. No. 62/331,577, filed May 4, 2016, the entire disclosure of which is expressly incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    This invention relates to a flowmeter device capable of monitoring the flow of different compressed gases (e.g., two, three, or four gases) supplied from pressurized cylinders, pipelines, and other containers in the welding industry. 
         [0003]    Welding equipment, such as MIG and TIG welders, require a supply of shielding gas. Common shielding gases are carbon dioxide, argon, nitrogen, and helium. It is important to control the appropriate flow rate of these gases, depending on the application, to ensure an efficient and quality weld. The flow rate is controlled using a flowmeter that includes a variable orifice control valve. The resulting amount of flow is calculated using a variable area meter, commonly called a rotameter. The rotameter includes a float inside a transparent tapered tube and a scale. The height of the float on the scale displays the rate of gas flow. 
         [0004]    Typically, flowmeters have scales calibrated for one, or perhaps two different gases. When a welder needs to change the shielding gas, they need to either change flowmeters or calculate flow rate using a correction factor. Either method adds time and cost to the welding process. 
         [0005]    Flowmeters can be made to function in two different ways, namely pressure compensated and non-compensated. Pressure compensated flowmeters are calibrated based upon a set pressure (e.g., a user can select 50 PSI is the set pressure) with the flow being adjusted with a variable orifice, e.g., needle valve. In MIG or TIG welding, the operator uses either a MIG gun or a TIG torch. Both the MIG gun and the TIG torch use inert shielding gases such as the shielding gases noted above (carbon dioxide, argon, nitrogen, and helium) or mixtures thereof. The flow of these shielding gases is normally controlled by the operator via an electric solenoid. Therefore, anytime the shielding gases are not flowing, the pressure in the lines builds to the set pressure (e.g. 50 PSI). Each time the operator energizes the solenoid, shielding gas starts to flow with a large surge of pressure until the pressure drops to whatever is necessary (can be as low as 1 to 2 psi) for the shielding gas to flow through the orifice at the desired flow rate that has been initially set by the operator. The operator can stop and start the solenoid dozens and sometimes hundreds of times per day. This surge wastes huge quantities of gas. 
         [0006]    With non-compensated flowmeters, the shielding gas flows through a fixed orifice with the flow rate being adjusted by changing the regulator pressure. The result is that there is little or no surge. Some time ago, a small regulator was added to the outlet of the compensated flowmeter. With the small regulator added to the outlet, all the operator had to do was to open the needle valve to its maximum and set the flow rate by adjusting the small regulator pressure setting. By doing this, the customer could reduce inert shielding gas consumption by as much as 60%. 
         [0007]    To this day, pressure compensated designs are still the most popular. Most manufacturers, however, offer flowmeters with a reduced preset pressure so that the flowmeters are less wasteful. Unfortunately there are drawbacks to the non-compensated and lower pressure designs. For example, there can be gas flow issues with extra long welding cables, or when working outside in the elements. 
         [0008]    A need exists for an improved gas flowmeter that addresses one or more of the above-noted deficiencies in an economical, simple to use manner. 
       SUMMARY 
       [0009]    This invention improves on the prior art by incorporating different scales for multiple, common shielding gases in a single flowmeter. 
         [0010]    The flowmeter of the present application can be produced in either pressure compensated and non-compensated versions. Moreover, the flowmeters can be calibrated over a wide range of set pressures, e.g. from about 15 psi to 80 psi). 
         [0011]    The pressure compensated versions of the present disclosure can be made with calibrated scales with different units of measurement. For example, the scales could be calibrated in liters per minute for international use outside the US, while the more common scale use in the US is a calibrated scale measured in cubic feet per hour. 
         [0012]    Also be recognize that any custom calibrated scale can be provided for special mixed inert gases 
         [0013]    Benefits and advantages of the present disclosure will become more apparent from reading and understanding the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is an elevational view of a flowmeter assembly. 
           [0015]      FIG. 2  is a top plan view of the flowmeter assembly of  FIG. 1 . 
           [0016]      FIG. 3  is a cross-sectional view of the flowmeter assembly taken generally along the lines  3 - 3  of  FIG. 2 . 
           [0017]      FIG. 4  is a cross-sectional view of the flowmeter assembly taken along the lines  4 - 4  of  FIG. 2 . 
           [0018]      FIGS. 5A-5H  are top perspective, bottom perspective, front elevational, rear elevational, first and second ends, and first and second cross-sectional views, respectively, of a flow meter body of the assembly. 
           [0019]      FIGS. 6A-6F  are top perspective, bottom perspective, elevational, top, bottom, cross-sectional views, respectively, of a flow meter cap of the assembly. 
           [0020]      FIG. 7A-7C  are elevation, end, and cross-sectional views, respectively, of a flow meter mount tube of the assembly. 
           [0021]      FIGS. 8A and 8B  are side and end view, respectively, views of a flow meter outer tube of the assembly. 
           [0022]      FIGS. 9A-9C  include different views of a flow meter label of the assembly. 
           [0023]      FIG. 10  is a longitudinal cross-sectional view of another embodiment of the flowmeter. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    This invention shows a flowmeter assembly  100  ( FIGS. 1-4 ) that uses a downstream variable orifice control valve  110  to control gas flow. The control valve  110  is typically mounted to the side of a flowmeter body  120  prior to the gas exit of the flowmeter  130 . A clear or transparent tube  140  ( FIG. 3 ), acrylic or similar material, is fixed at a first end  142  to the flowmeter body  120 , for example, via cooperating threaded regions on a top portion  122  of the flowmeter body and the first end of the clear tube, respectively. A cap  150  is mounted to second end or top portion  144  of the clear tube  140 , and secured thereto, for example, by cooperating threaded regions  152 ,  144 A on the cap and top portion, respectively. The body  120 , clear tube  140 , and cap  150  form a pressure chamber  155  of the flow meter assembly  100 . In a center of the pressurized chamber  155  are two floats such as spherical floats  160 ,  170  inside a clear (transparent), tapered (shown as decreasing from top to bottom as seen in  FIGS. 3 and 4 ), inner hollow member or rotameter tube  180 . More particularly, the rotameter tube  180  forms a chamber  185  sealed at its first, lower end  182  to the flowmeter body  120  and connected at its second, upper end  184  to the cap  150 , specifically to a central portion  152  of the cap. The chamber  185  of the rotameter tube  180  receives the floats  160 ,  170  therein. The top float  160  is preferably a first colored (e.g., white) polytetrafluoroethylene, or similar material, and the bottom float  170  is preferably a stainless steel, or similar material (e.g., silver), i.e., the floats are different densities, and/or formed of different materials having different densities, and are distinct, different colors. The bottom float  170  is formed of a material having a greater density than the top float  160 . The rotameter tube  180  leads to and is in fluid communication with the gas inlet  190  ( FIGS. 1-2 ), which is also mounted to the side of the flowmeter body  120  and preferably the gas inlet is at a location spaced from the control valve  110 , shown here as being located at a circumferentially spaced location on the body from the control valve. The gas flows from the inlet into first end  182  of the inner hollow member/rotameter tube  180  where the flow lifts the floats  160 ,  170  depending on the gas flow rate through the rotameter tube. Since the upper float  160  is less dense, it will move more readily than the lower float  170 , and at increased flows both floats may be lifted to a certain height in the rotameter tube  180  above the illustrated initial position ( FIGS. 3-4 ) representative of no flow. Thus, the upper float  160  is more sensitive to low flow rates and less dense gases (e.g., helium) whereas the lower float  170  will move in response to higher flow rates and more dense gases (e.g., carbon dioxide, argon, or nitrogen). If the stainless steel lower float were used for helium, for example, the scale limits would be undesirable, and thus the reason that the upper float with the smaller specific gravity is used for less dense gases, and the second, lower float with the greater specific gravity is useful to measure gas flow for more dense gases such as carbon dioxide, argon, or nitrogen. 
         [0025]    The gas flow continues to an upper, second end  184  of the inner hollow member/rotameter tube  180  at the cap  150 , and the shielding gas flow proceeds toward or communicates with the interior of the transparent tube  140  which, in turn, communicates with the control valve  110  as the gas flow continues toward the outlet/exit  130 . 
         [0026]    Outside of the pressurized chamber  155  is a clear (transparent), free rotating unpressurized tube or outer cover  200  ( FIGS. 3-4 ). The cover  200  rotates relative to the cap  150  at its first, upper end  202  and likewise rotates relative to the body  120  at its second, lower end  204 . The cover  200  has multiple scales  210  ( FIGS. 3-4 and 9A ) associated therewith to accommodate more accurate calibration of the particular shielding gas used in the welding process. For example, the scales  210  may be located on an inside diameter of this unpressurized tube/cover  200 . By way of example, the printed scales  210  for multiple (e.g., four) gases ( FIG. 9A ) are provided. Therefore, since the scales  210  ( FIGS. 3-4, and 9A ) are secured or fixed to the inside diameter of the tube/cover  200 , the scales can be selectively rotated via rotation of the tube/cover relative to the body  120  and cap  150  whereby the desired scale faces the operator for the necessary gas type flow reading. The thick outer cover  200  also provides protection for the pressurized inner tube  140  and pressurized inner hollow member/rotameter tube  180 , as well as protecting the scale printing  210  from dirt and scratches. 
         [0027]    The scales  210  ( FIG. 9A ) are calibrated to read to the center of the floats  160 ,  170 . When reading the flow rate of carbon dioxide, argon, or nitrogen the operator uses the stainless steel ball  170 . When reading the flow rate of helium the operator uses the white ball  160 . Different balls  160 ,  170  formed from different density material (material with different specific gravities) or different materials having different densities are used because the density of helium is significantly less than the other shielding gases. If the stainless steel ball  170  were used for helium, the scale limits  210  would be undesirable relative to the scales associated with the other shielding gases or combinations of shielding gases (e.g., special mixed inert gases such as 75% argon/25% carbon dioxide or 70% argon/30% helium could be used, although still other mixtures could be used without departing from the scope and intent of the present disclosure). Using a float or ball  160  with a smaller specific gravity provides an optimal scale size  210  for reading helium gas flow rate in typical welding applications. In addition, the scales  210  are nonlinear (see  FIG. 9B ) for greater accuracy. Some prior art manufacturers use linear scales that, as a result, are not accurate over the whole flow range. These linear scale manufacturers target a middle of the flow range in an attempt to provide the most accurate spot on the scale, but as the float moves away from that position, the amount of error likewise builds in either direction (up or down). Since the hollow member or rotameter tube  180 , tube  140 , and the cover  200  are all transparent, the operator is able to view the position of the first and second floats  160 ,  170  and determine the shielding gas flow rate by comparing the positions of the floats relative to the specific scale  210  on the inner diameter of the cover  200  to determine the flow rate, and make appropriate adjustments to the flow via the control valve  110 . 
         [0028]    Two additional features are shown in  FIG. 10 . Specifically, a seal ring or o-ring  230  serves as a drag or friction member between the cover  200  and the flowmeter body  120 . This stabilizes and holds the desired rotational position of the cover relative to the body once the operator has oriented the cover with the specific scale  210  as desired. Vibration or bumping of the cover  200  will not inadvertently move the scale  210  relative to the desired orientation relative to the body  120 . Also in  FIG. 10 , the inlet may become a dual port inlet  240  in which suitable connection may be made with the shielding gas supply (not shown), and the second port  242  can receive a plug  244  since it will not be used. This allows the operator to locate the inlet at a desired location on the flowmeter  100 . 
         [0029]    This written description uses examples to describe the disclosure, including the best mode, and also to enable any person skilled in the art to make and use the disclosure. Other examples that occur to those skilled in the art are intended to be within the scope of the invention if they have structural elements that do not differ from the same concept, or if they include equivalent structural elements with insubstantial differences.