Abstract:
Wireless flow monitoring devices are described. In one example, a device to wirelessly monitor a flow of material is described that includes a housing having a first surface and a second surface opposite the first surface, the second surface having an aperture, a lever secured within the housing to move in response to the flow of material, and a paddle arm forming at least a portion of a first arm of the lever, where an end of the paddle arm extends out the aperture of the second surface of the housing, and where a paddle is affixed to the paddle arm to be positioned within the flow of material. The device includes a magnet that is actuated by a second arm of the lever to move an amount proportional to the first arm of the lever, a portion of the magnet extending beyond the first surface of the housing so that a motion path of the portion of the magnet extending beyond the first surface of the housing is disposed within a channel of a wireless position monitor mounted to the first surface of the housing, where the channel serves as a sensor to detect movement of the magnet.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    This patent relates generally to flow control devices and, more particularly, to wireless flow monitoring devices. 
       BACKGROUND 
       [0002]    The flow of material (e.g., fluids, solids, etc.) in pipelines or other conduits is an important function in modern industrial and commercial processes. In many settings, it is important to monitor and detect whether material is flowing in a pipeline or other conduit and to respond in accordance with an overall control strategy. In many applications, one or more flow switches may be used for this purpose. 
         [0003]    Many known flow switches function to complete (make) or interrupt (break) an electrical circuit when a flow or a no-flow condition is detected within a pipeline. Cables wired to the electrical circuit may electrically couple the flow switch to a process controller, a motor or pump, and/or any other device within a process control system to provide or assert a signal when flow stops, remove or shut off a signal when flow is adequate, start a motor in response to detecting a flow, stop a motor in response to a no-flow condition, or implement any other appropriate action. 
       SUMMARY 
       [0004]    Wireless flow monitoring devices are described. In one example, a device to wirelessly monitor a flow of material is described that includes a housing having a first surface and a second surface opposite the first surface, the second surface having an aperture, a lever secured within the housing to move in response to the flow of material, and a paddle arm forming at least a portion of a first arm of the lever, where an end of the paddle arm extends out the aperture of the second surface of the housing, and where a paddle is affixed to the paddle arm to be positioned within the flow of material. The device includes a magnet that is actuated by a second arm of the lever to move an amount proportional to the first arm of the lever, a portion of the magnet extending beyond the first surface of the housing so that a motion path of the portion of the magnet extending beyond the first surface of the housing is disposed within a channel of a wireless position monitor mounted to the first surface of the housing, where the channel serves as a sensor to detect movement of the magnet. 
         [0005]    In another example, a wireless flow monitoring device includes an enclosure having a bottom surface and a top surface, a paddle arm coupled to the enclosure and extending out an opening in the bottom surface of the enclosure, and a paddle affixed to the paddle arm, the paddle and the paddle arm forming a first lever arm to rotate about a pivot point within the enclosure in response to material flowing within a pipe. The device also includes a second lever arm to rotate about the pivot point an amount proportional to the rotation of the first lever arm, a portion of the second lever arm extending beyond the top surface of the enclosure, the portion of the second lever arm having a magnetic array to be positioned within a sensor channel of a wireless position monitor to detect movement of the magnetic array. 
         [0006]    In yet another example, a flow monitoring device includes a housing having a cavity formed by a base and a cover, a hollow body affixed to the base about an opening in a first surface of the base, the hollow body enabling the device to be installed on a conduit through which material flows, the flow of the material being monitored by the device, and a paddle arm extending through the opening in the first surface of the base through the hollow body, the paddle arm being coupled to the housing to enable the paddle arm to rotate in response to the flow of the material within the conduit. The device further includes a paddle affixed to the paddle arm and positioned within the conduit and a magnet extending from the pivot joint in a direction substantially opposite the paddle arm to rotate an amount proportional to the rotation of the paddle arm, the magnet extending beyond a top surface of the housing to enable a position monitor to be mounted to the device to monitor the flow of the material by monitoring the rotation of the magnet. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1A  is an illustration of a known paddle type flow switch. 
           [0008]      FIG. 1B  is an exploded view of the known flow switch shown in  FIG. 1A . 
           [0009]      FIG. 2  is a perspective view of an example flow switch attached to a wireless position monitor in accordance with the teachings of this disclosure. 
           [0010]      FIG. 3  is another known paddle type flow switch shown in disassembled form. 
           [0011]      FIG. 4  is a perspective view of another example flow switch attached to the wireless position monitor of  FIG. 2  in accordance with the teachings of this disclosure. 
           [0012]      FIG. 5  is an illustration of an example fully-assembled flow switch according to the teachings of this disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    In accordance with many known approaches, a flow switch may be integrated within a process control system by physically wiring the flow switch into the control system. Such wiring can incur significant costs, both upfront during set up and installation, as well as during ongoing maintenance. These known approaches may require a lot of electrical wires/cables and/or may increase the amount and/or the size of conduits used to run the wires within the process control system as well as the sizes of cable trays. Also, wiring can be costly and/or impractical in locations that are difficult to access and install the wiring. Furthermore, additional wiring in a process control system may require expansion cards for a process controller to provide additional input points to connect each wire to the controller to enable all components to properly communicate, thereby incurring additional cost and/or inconvenience. Additionally, electrically wiring a flow switch may not be approved for use in hazardous (classified) areas where unsafe environments (e.g., class I—flammable gases or vapors, class II—combustible dust, etc.) pose a risk of explosion or other danger. 
         [0014]    The foregoing problems may be alleviated by communicating the flow monitored by flow switches via intrinsically safe wireless technology. By wirelessly communicating the flow measured by a flow switch, it is possible to eliminate the labor and expense of installing electrical cables, running the cables across a process space through conduits, and finding available input points to physically terminate the wires with connections to a controller and/or other device. Instead, a single gateway may receive wireless signals from multiple components and communicate each of those signals via Hart, OLE for Process Control (OPC), modbus Ethernet, serial  485 , or any other communication protocol without the need for discrete input cards to receive separate wires from each additional component. Furthermore, monitoring flow without hardwired flow switches enables the monitoring of material flow at locations that would be otherwise difficult and/or impractical to access via many known methods. 
         [0015]    Additionally, many known implementations of wireless technology include wireless devices designed to be intrinsically safe so as to be approved for use in hazardous (classified) environments. For example, it is known that an intrinsically safe wireless position monitor may be attached to a control valve to detect movement of the valve shaft or stem to determine the position of the valve and communicate the position back to a controller without the need to run physical wires in a process space. However, many of the known flow switches cannot be connected to wireless position monitors in a manner that enables the position monitors to obtain a reliable reading of the flow switch. As such, with these known approaches, the only recourse is to either physically wire a flow switch to a process control system (with all its related costs and limitations on the type of environment) or to forego measuring flow at that particular location within the process control system. 
         [0016]      FIGS. 1A and 1B  illustrate a known paddle type flow switch  100 . Specifically,  FIG. 1A  illustrates the flow switch  100  completely assembled with a cover  102  and  FIG. 1B  illustrates an exploded view of the flow switch  100  without the cover  102  to show the internal components of the flow switch  100 . The flow switch  100  is similar in some respects to the flow switch described by Shafique et al. in U.S. Pat. No. 6,563,064, which is hereby incorporated herein by reference in its entirety. While a complete description can be obtained from Shafique et al., in summary, the flow switch  100  includes a paddle  104  attached to a paddle arm  106  that extends through a pipe adapter  108  and through an opening  110  of a bracket, base, or housing  112  of the flow switch  100 . In use, the flow switch  100  is coupled to a pipe (pipe used herein includes pipe or any other conduit) with the paddle  104  extending into the pipe to interact with material in the pipe. The paddle  104  and paddle arm  106  are configured to act as a first lever arm  114  that is moved or displaced by a change in the flow of material in the pipe to actuate a second lever arm  116  that engages or actuates an electrical switch  118  (e.g., a snap switch). Once engaged, the electrical switch  118  may provide a signal (e.g., a contact closure) to a component in a process control system that has been physically wired to the flow switch  100 . 
         [0017]      FIG. 2  is a perspective view of an example flow switch  200  attached to a wireless position monitor  206  in accordance with the teachings of this disclosure. The example flow switch  200  may be similar in some respects to the flow switch  100  shown in  FIGS. 1A and 1B . However, the example flow switch  200  has been modified as discussed below. 
         [0018]    Attached to a second lever arm  201  is an array of magnets  202  (which may be referred to as a target array) configured to extend beyond the top of the base  112 . By coupling, either directly or indirectly, the target array  202  to the second lever arm  201 , the target array  202  acts as an extension of the second lever arm  201  and moves about a fulcrum of the lever an amount proportional to the movement of the paddle  104  when flow conditions within a pipe change. The target array  202 , which extends beyond the top of the base  112 , is configured to be positioned within a channel  204  of a wireless position monitor  206  such that when the target array  202  moves along the channel  204 , the position monitor  206  can measure that movement to indicate the material flow conditions within a pipe. While the position monitor  206  may detect smaller movements, the target array  202  may span at least ¼″ along the channel  204 . To ensure accurate and reliable measurements, the position monitor  206  may be securely mounted to the flow switch  200  via, for example, a bracket  208 . Once movement of the paddle  104  has been detected via the position monitor  206  detecting movement of the target array  202 , the position monitor  206  may wirelessly transmit the collected data to a process controller and/or other device for analysis and/or other response. 
         [0019]      FIG. 3  depicts another known paddle type flow switch  300  shown in disassembled form. The flow switch  300  of  FIG. 3  is similar to the flow switches described by Garvey in U.S. App. Pub. No. 2008/0258088, which is hereby incorporated herein by reference in its entirety. While a complete description can be obtained from Garvey, in summary, the flow switch  300  includes a paddle  302  attached to a paddle arm  304  that extends inside a pipe adapter  308  and connects to a pivot pin or rod  306  that extends across the pipe adapter  308  through an aperture  310 . A lever arm  312  is coupled to an end of the pivot rod  306  to rotate about the pivot rod  306  an amount proportional to the rotation of the paddle arm  304  when a change in flow of material in a pipe causes the paddle  302  to move. The movement of the lever arm  312  is configured to actuate an electrical switch  314  (e.g., a snap switch), which may be physically wired to communicate with other components in a process control system. 
         [0020]      FIG. 4  is a perspective view of another example flow switch  400  attached to the wireless position monitor  206  of  FIG. 2  in accordance with the teachings of this disclosure. The example flow switch  400  is similar in some respects to the flow switch  300  shown in  FIG. 3 . However, the flow switch  400  has been modified as discussed below. A target array  402  is coupled either directly or indirectly to an end of the pivot rod  306  to rotate about the pivot rod  306  an amount proportional to the movement of the paddle  302 . The wireless position monitor  206  may be mounted to the flow switch  400  to securely position the target array  402  within the channel  204  of the position monitor  206 . To position the target array  402  within the channel  204  of the position monitor  206 , the target array  402  may be configured to extend beyond the top of a base  404  of the flow switch  400  as illustrated in  FIG. 4 . 
         [0021]    The wireless position monitor  206  shown in  FIGS. 2 and 4  may be a model 4310 Wireless position monitor made by TopWorx Inc., a subsidiary of Emerson Electric Company. However, the teachings of this disclosure may be implemented using any other wireless position monitor. Use of the wireless position monitor  206  enables the use of flow switches (e.g., the example flow switches  200  and  400 ) in virtually any location without the need to run electric wires and/or conduit throughout a process control system. Not only may this provide significant cost savings in installation and maintenance, it also simplifies the linking of multiple devices to a controller because a single gateway can receive numerous wireless signals, whereas hardwiring multiple devices requires each device to have an independent input point. 
         [0022]    Additionally, wireless position monitors, such as the position monitor  206 , may be intrinsically safe. Thus, these wireless position monitors are approved for any environment (i.e., both hazardous and non-hazardous work conditions). More specifically, these wireless position monitors can be implemented with the disclosed example flow switches  200  and  400  in any environment because the flow switches  200 ,  400  are purely mechanical devices that do not require any electrical connections unlike many known flow switches. This is made possible by the linkage-less and/or non-contact detection of movement of the target arrays  202  and  402  by the position monitor  206 . Furthermore, not only may the position monitor  206  be intrinsically safe during operation, it may have intrinsically safe power modules (e.g., batteries). As a result, if allowed under standard operating procedures of the particular process system, a user may change the power modules in the field without the need for obtaining a hot work permit. Alternatively, the position monitor  206  may use local power to power its operation. While this implementation requires a power cord, it still avoids the use of wiring electrical cables up as with many other known flow switches. 
         [0023]      FIG. 5  depicts an example flow switch  500  according to the teachings of this disclosure. As with known flow switches, the example flow switch  500  includes a cover  502  that attaches to a base  504 . However, the cover  502  is adapted to provide space for a target array  506  to extend beyond the top of the flow switch  500  via a notch or slot  508 . This allows the target array  506  to pass through the channel  204  of the position monitor  206  (shown in  FIGS. 2 and 4 ) for reliable monitoring of the flow switch  500 . Furthermore, the cover  502  also includes holes  510  to enable the position monitor  206  to be secured to the flow switch  500 . Additionally, the cover  502  may be flat to facilitate the mounting of the position monitor  206 . 
         [0024]    The example cover  502  of the flow switch  500  may be applied to either of the example flow switches  200  or  400  described above. Furthermore, an alternative configuration (not shown) of the example cover  502  may include a hollow protrusion in which the target array  506  may sit. Such a protrusion may be dimensioned to fit within the channel  204  of the position monitor  206  to enable the internal mechanisms of the flow switch  500  to be completely enclosed. 
         [0025]    Similarly, the example flow switches  200 ,  400 , and  500  disclosed herein are provided by way of example only. Any other configuration of the base (e.g., the base  112  of  FIG. 2 ), the lever arms (e.g., the second lever arm  116  of  FIG. 2 ), the target array (e.g., the target array  202  of  FIG. 2 ), the cover (e.g., the cover  502  of  FIG. 5 ) and/or the method of mounting the position monitor  206  that is similar to that which is disclosed herein is contemplated by this disclosure. For example, while  FIGS. 2 and 4  show the flow switches  200  and  400  without an associated electrical switch (e.g., the switch  118  shown in  FIG. 1A ), the example flow switches  200  and  400  may be configured to include an electrical switch  118  as well as a target array (e.g., the target array  202 ) to enable hardwired and/or wireless implementations of the flow switches  200  and  400 . 
         [0026]    Furthermore, the example flow switches  200 ,  400 , and  500  described herein may be implemented in virtually any process control system. For instance, the example flow switches described herein may be applied to conditions of both vacuum and positive flow in either batch or continuous processes. Furthermore, the example flow switches described herein are suitable for detecting the flow of virtually any material including liquids, gases, and/or powder/dust.