Patent Application
20160069729
Embodiments are generally related to level sensors, coaxial probes, and guided wave radars.
Coaxial probes have been used in fluid level sensors to measure fluid levels in closed tanks, open tanks, reservoirs, and other environments. Radio frequency (“RF”) electronics can be attached with the signal passing into the sensor's inner conductor while the outer conductor is connected to ground. These sensors are sometime referred to as guided wave radar level sensors or microwave level sensors. To measure a fluid level, the probe can be positioned vertically at a known height with one end immersed in a fluid. The fluid flows around and into the probe. Activating the RF electronics and reading the sensor output indicates the portion of the probe length that is immersed.
The coaxial probes have an inner rod, an outer shell, and a spacer that centers the rod within the shell. The spacers cannot be solid because solid spacers prevent the fluid from flowing up the inside of the probe between the inner rod and the outer shell. Currently used coaxial probes use specially shaped spacers such as stars or disks cut along a chord or two. Assembling coaxial probes with these specially shaped spacers requires that the spacer be slid down the length of the inner rod. Such assembly can be difficult, especially in the field. Systems and methods for more easily assembled coaxial probes are needed.
The following summary is provided to facilitate an understanding of some of the innovative features unique to the disclosed embodiments and is not intended to be a full description. A full appreciation of the various aspects of the embodiments disclosed herein can be gained by taking the entire specification, claims, drawings, and abstract as a whole.
It is, therefore, one aspect of the embodiments that U-shaped spacers are snapped onto the inner rod instead of being slid into position along the rods length. The U-shaped spacers can be held in position by friction or by snapping them onto turned down sections of the inner rod. The friction holding the U-shaped spacer in position can be far greater than that in systems wherein spacers are slid along the rod. The inner rod, with spacers attached, can be slid into the outer shell until it reaches its proper position. The inner rod can be locked in position by locking the U-shaped spacers into position.
Another aspect of some embodiments is that there is a flow channel between the inner rod and a portion of the U-shaped sensor. The flow channel can be a gap along the inner circumference of the spacer. The gap also provides a location where the U-shaped spacer can flex as it is snapped onto the inner rod.
Different embodiments can employ any of a number of ways to lock the U-shaped spacer in place within the outer shell. Fasteners such as pins, nails, staples, or screws can be driven through the outer shell and into the spacer. Note that such fasteners must be of a size or material as to not impact the fluid level measurements. Indentations or crimps in the outer shell can also lock the U-shaped spacer in place. Another way to lock the U-shaped spacer in place is to press a hinged cutout into the spacer. A hinged cutout can be pulled back out for disassembly of the probe.
The spacers must be nonconductive and substantially impervious to whatever fluid is being measured. PTFE is a good choice although some applications require more exotic materials like PEEK.
The inner rod and the outer shell must also be substantially impervious to whatever fluid is being measured. Stainless steel is often a good choice. Particularly harsh conditions may require a more exotic alloy such as a superalloy or a material similar to Monel. Monel alloys are certain nickel alloys having at least 62% nickel and 27% copper. Examples of superalloys are Hastelloy, Inconel (e.g., IN100, IN600, IN713), Waspaloy, Rene alloys (e.g., Rene 41, Rene 80, Rene 95, Rene N5), Haynes alloys, Incoloy, MP98T, TMS alloys, and CMSX (e.g., CMSX-4) single crystal alloys.
Some embodiments enhance fluid flow into the probe by having holes or perforations in the outer shell.
Further aspects of certain embodiments have threaded or flanged ends on the inner rod and the outer shell so that additional lengths of inner rod and outer shell can be attached end to end to produce a long probe from shorter parts. The U-shaped spacers can be snapped onto the inner rod lengths at any time during assembly up to the time when the outer shell blocks the spacer from being snapped on.
The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form a part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention.
The particular values and configurations discussed in these non-limiting examples can be varied and are cited merely to illustrate at least one embodiment and are not intended to limit the scope thereof.
The embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. The embodiments disclosed herein can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
The coaxial probe 601 of
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
