Retractable monolithic sensor assembly, controller, and methods of making and installing same

Abstract

Telescopic monolithic sensor assemblies, controllers, and methods of making and installing the same are disclosed. The sensor assembly includes a sensor head sized to completely traverse the diameter of the tube such that its electrodes sample a voltage indicative of the entire tube flow across the diameter of the tube flow. An improved rod design is included that reduces the insertion force and increases the lateral stability of the sensor head. Improved insertion devices that provide independent axial insertion and rotation are disclosed. An improved core that minimizes interference of a magnetic field and reduces manufacturing costs is disclosed. An improved controller with improved sensitivity is disclosed.

Description

[0001] This application is a divisional application of the patent application for invention with the international filing date of December 27, 2018, national application number 201880089234.4, and invention title "Retractable Monolithic Sensor Assembly, Controller, and Methods of Making and Installing the Same".

[0002] Related Applications

[0003] This application claims the priority of U.S. Provisional Application 62 / 611,251, filed on December 28, 2017, the entire disclosure of which is incorporated herein by reference. Background Art

[0004] The disclosed embodiments generally relate to electromagnetic flow meters.

[0005] Current insertion flow meters sample a small area of the flow through the pipe. Even those designed for large pipes only sample a few small cross-sections. Then, they average these readings in an attempt to obtain an accurate flow measurement. All averaging has some weighting; the most common is to give each reading equal weight. Unfortunately, if the flow varies with respect to the flow used to calibrate the meter, then even if positioned such that each sensor has an equal annular area and is given an equal rating, it does not result in an accurate measurement. Giving unequal weights can result in accurate readings, but detailed information about the flow pattern is required to assign these weights. If the flow changes, the meter will be inaccurate. Separate cores require multiple preamplifiers. This results in a bulky and expensive meter.

[0006] Current insertion flow meters also utilize threaded joints in the body of the meter. There is a risk of the threaded joint rotating and backing out after installation. Using the threaded joint as part of the electromagnetic sensor head is challenging because the sensor must remain aligned and not be allowed to rotate after installation. Snap fits prevent axial movement but not rotation. They are not secure when bent.

[0007] In addition, traditional insertion meters trade off two factors in the rod design: insertion force and flexural strength. The smaller the rod, the less force required to install the meter. However, thin rods are subject to unwanted flexure, vibration, fatigue, and breakage.

[0008] Furthermore, the electrode wires in current insertion meters need to be shielded from the electromagnetic fields of their cores. Typical cores achieve this by routing the electrode wires along the non-field-producing middle of the core. This can make the machine expensive, difficult to install, and increase the complexity of coil winding.

[0009] An insertion flow meter is installed into a flow tube using a thermal tap adapter mounted to a ball valve. As a result, after installation, a conventional thermal tap adapter anchors the meter at the top of the adapter. This is the point farthest from the force of the flow and the longest moment arm. This causes excessive flexure and vibration that negatively affect the accuracy of the meter.

[0010] Manually insertable thermal separable tap insertion flow meters often have their alignment detached from their installation. That is, the meter can be screwed onto a valve fitting and then aligned later. However, mechanically assisted thermal separable tap flow meters are typically locked in the orientation in which they are installed. Screwing the meter onto the valve fitting determines the angle of the meter with respect to the flow. This means that installers must often trade off between the correct installation torque of the fitting and the correct angle of the meter with respect to the flow.

[0011] The accuracy of insertion flow meters also depends on how consistently they are installed. Any difference in the installation angle between the location where the meter is calibrated and the location where the meter is installed will degrade the accuracy of the meter.

[0012] Current insertion flow meter controllers must compensate for DC bias on the electrodes, which may be caused, for example, by the electrochemical interaction of the electrodes. This reduces the accuracy of the meter. Additionally, other insertion flow meters require precise timing and switching circuitry to read the signal, increasing the overall complexity and cost of the meter. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A perspective view of an example sensor assembly in accordance with the disclosed embodiments is shown;

[0014] Figure 2 shown in accordance with the disclosed embodiments Figure 1 of the sensor assembly as viewed in the direction of system flow.

[0015] Figure 3 shown in accordance with the disclosed embodiments Figure 2 of the cross-sectional view along section line III-III.

[0016] Figure 4 shown in accordance with the disclosed embodiments Figure 3 of the cross-sectional view along section line IV-IV.

[0017] Figure 5 shown in accordance with the disclosed embodiments Figure 4 of the cross-sectional view along section line V-V.

[0018] Figure 6 shown in accordance with the disclosed embodiments Figure 4 of the detailed view of detail 6.

[0019] Figure 7 Shows a detailed view of detail 7 according to the disclosed embodiments. Figure 4 of detail 7.

[0020] Figure 8 Shows a perspective view of an example sensor head according to the disclosed embodiments without an example sensor head tube.

[0021] Figure 9 Shows a side view of an example sensor head according to the disclosed embodiments without an example sensor head tube.

[0022] Figure 10 Shows a front view of an example sensor head according to the disclosed embodiments without an example sensor head tube.

[0023] Figure 11 Shows a detailed view of detail 11 according to the disclosed embodiments. Figure 8 of detail 11.

[0024] Figure 12 Shows a schematic view of an example sensor head and rod during assembly according to the disclosed embodiments.

[0025] Figure 13 Is a cross-sectional view along section line XII-XII of Figure 12 according to the disclosed embodiments.

[0026] Figure 14 Is a schematic view of a sensor head tube and rod according to the disclosed embodiments.

[0027] Figure 15 Shows a schematic view of an example sensor head and rod after connecting an example sensor head and rod together according to the disclosed embodiments.

[0028] Figure 16 Is a cross-sectional view along section line XVI-XVI of Figure 17 according to the disclosed embodiments.

[0029] Figure 17 Shows a schematic view of an example anchor before inserting an example sensor head according to the disclosed embodiments.

[0030] Figure 18 Is a cross-sectional view along section line XVIII-XVIII of Figure 17 according to the disclosed embodiments.

[0031] Figure 19 Is a cross-sectional view along section line XIX-XIX of Figure 19 according to the disclosed embodiments.

[0032] Figure 20 and Figure 21 illustrates an example sensor assembly in two stages of installation according to the disclosed embodiments.

[0033] Figure 22 illustrates a perspective view of an example mechanical insertion device 260 according to the disclosed embodiments.

[0034] Figure 23 illustrates a front schematic view of an example mechanical insertion device 260 according to the disclosed embodiments.

[0035] Figure 24 illustrates a front schematic view of an example mechanical insertion device according to the disclosed embodiments.

[0036] Figure 25 illustrates a schematic perspective view of an example controller and a line emission light source according to the disclosed embodiments.

[0037] Figure 26 illustrates according to the disclosed embodiments Figure 25 schematic top view of.

[0038] Figure 27 illustrates according to the disclosed embodiments Figure 25 schematic front view of.

[0039] Figure 28 illustrates a magnetic field density map of an example coil and an example core according to the disclosed embodiments.

[0040] Figure 29A and Figure 29B illustrates an electrical schematic block diagram of a controller and a sensor head according to the disclosed embodiments.

[0041] Figure 30 illustrates a method according to the disclosed embodiments; and;

[0042] Figure 31 illustrates according to the disclosed embodiments when viewed in the system flow direction Figure 1 sensor assembly of Figure 24 together with the mechanical insertion device of. DETAILED DESCRIPTION

[0043] Figure 1FIG. illustrates an overall perspective view of an example sensor assembly 101 mounted above and within a flow tube 170. It should be noted that only a portion of the flow tube 170 is shown in its entirety. For clarity, other portions of the flow tube 170 are shown in dashed lines. The flow tube 170 is a section of a system, typically a commercial or industrial system, in which the system designer or customer desires to measure the system flow 172 (rate or volume or mass flow) therein. The flow tube 170 can be a tube of any size diameter. The sensor assembly 101 will be appropriately scaled to the size of the tube such that the sensor head 100 and associated components (discussed below) span the entire inner diameter of the tube. Typical industrial use is generally for tubes having diameters between one inch and 24 inches, although the disclosed embodiments are equally applicable to tubes up to 80 inches and larger. Many industrial and commercial systems utilize 6 - 12 inch tubes that are equally compatible with the sensor assembly 101. The example sensor assembly 101 is particularly advantageous for tubes having a size greater than six inches, in which prior sensors were more reliant on assumptions about the fluid flow within the tube.

[0044] Example systems include, but are not limited to, coolers, HVAC (heating, ventilation, and air conditioning), food processing, water treatment, water, water distribution, gas, agriculture, chemical refining and processing, and liquid, slurry, petrochemical, and pharmaceutical systems. For the remainder of this specification, we will refer to "fluid" as meaning any fluid or fluid-like material that is capable of inducing an electric current when flowing through a magnetic field. The sensor assembly 101 can be used with other fluids and systems provided the fluid has sufficient conductivity to induce an electric current when flowing through a magnetic field. Most water-based fluids possess this property. The system flow 172 within the flow tube 170 is generally parallel to the tube and perpendicular to the longitudinal path of the sensor assembly. As described below, the relative motion between the system flow 172 and the stationary sensor assembly 101 generates an electrical signal that is then converted into flow velocity or volume or mass flow.

[0045] The sensor assembly includes a sensor head 100 that generates a magnetic field and measures the electric potential (voltage or "V") generated by the flow velocity at at least one top electrode and at least one bottom electrode, which will be discussed below. The voltage is electrically carried to a controller 300 mounted on the outside of the flow tube 170. The internal construction and function of the sensor head 100 will be discussed in more detail below.

[0046] Typically, upon installation of the system, valve 120 is attached to flow tube 170. Valve 120 and flow tube 170 may have a short section 171 of intermediate tubing, which may be part of or attached to flow tube 170. However, such a section 171 will only affect the overall length required for the disclosed sensor assembly 101, which can be readily telescoped depending on the application. As such, this section will not be discussed further. Valve 120 (typically a ball valve) has a sufficient direct path through its center when open to allow sensor head 100 to be inserted through valve 120 during installation of the sensor assembly. Valve 120 has an axis 114 at the center of valve 120, and this axis 114 is perpendicular to flow tube 170 and system flow 172. The accuracy of sensor head 100 and the resulting flow velocity depend on the extent to which the longitudinal axis of sensor head 100 is perpendicular to system flow 172. Also, since sensor head 100 is inserted through valve 120 during installation (discussed below), the longitudinal axis of sensor head 100 should coincide with axis 114 when aligned. As will be discussed below, the alignment features in exemplary sensor assembly 101 have improvements over previously known sensors.

[0047] Prior to installation, sensor head 100 is retracted within thermal tap adapter 130. At installation, thermal tap adapter 130 is connected to valve 120. Thermal tap adapter 130 can be removably connected, such as by a threaded connection between valve 120 and thermal tap adapter 130, or alternatively, fixedly connected via pressing, welding, etc. Sensor head 100 is attached to a rod, discussed further below, which extends through thermal tap adapter 130 to mechanical insertion device 260, also discussed further below. After thermal tap adapter 130 is connected to valve 120, valve 120 is opened and the sensor head is inserted into flow tube 170 until the sensor head bottoms out. Further details regarding installation will be discussed below.

[0048] Figure 2 is shown Figure 1The sensor assembly when viewed in the direction of system flow 172. There are holes in the top, bottom, and middle regions of the sensor head 100, in which the electrodes 105, 106, 107, 108, 109, 110 slightly protrude to contact the fluid flow in the flow tube 170. As shown, there are a left top electrode 105, a right top electrode 106, a left bottom electrode 107, a right bottom electrode 108, a left center electrode 109, and a right center electrode 110. The center electrodes 109, 110 are used as ground or reference electrodes. When performing flow measurement, a potential measurement (voltage) is made between the corresponding top and bottom electrodes. For example, to measure the left part of the sensor head 100, a voltage measurement is made across the left top electrode 105 and the left bottom electrode 107. To measure the right part of the sensor head, a voltage measurement is made across the right top electrode 106 and the right bottom electrode 108. In another configuration, the top electrodes 105, 106 and the bottom electrodes 107, 108 are each electrically connected separately, so that separate measurements are made, i.e., between the top and bottom electrodes.

[0049] This arrangement of the electrodes results in only two measurement depths at the top and bottom of the sensor head 100, i.e., close to or adjacent to the inner surface 173 of the flow 170 (on the opposite sides of the flow tube 170). It should be noted that the top electrodes 105, 106 and the bottom electrodes 107, 108 span the diameter of the flow tube 170. That is, the top electrodes 105, 106 and the bottom electrodes 107, 108 are adjacent to the radially opposite inner surfaces 173 of the flow tube 170. Measuring the potential between the two measurement depths across the diameter of the flow tube 170 results in improved accuracy compared to making multiple cross-sections of the measurement tube in the previous sensors and then averaging the measurement results together. The increased distance between the extended electrodes also increases the voltage potential and improves the meter performance. All the fluid in the sensing region will be included in the voltage potential integration and will contribute to the reading of the meter. The larger the region, the more fluid is included and the more accurate the meter. The previously known sensors use less than 10% of the large tube diameter. The inclusion of a large sampling region in the example sensor head 100 allows for high performance in regions of varying flow patterns. Although the high-speed and low-speed regions may shift, because they are all included in a single integration, they will still contribute to the overall voltage regardless of their position. Since there are only two measurement depths, the sensor head 100 can be easily scaled to tubes of any size without having to re-adjust the electrode spacing and remove the wired connection between the electrodes and the signal conditioning circuitry, compared to other sensors that have to average several voltage measurement results across the tube diameter.

[0050] Figure 3 is shown Figure 2Cross-sectional view along section line III-III. Note that although section line III-III appears in the center, i.e., along axis 114, it is offset such that Figure 3 only certain components in the section are shown, as will be clear from the remainder of the disclosure. The sensor head 100 is attached to the large-diameter rod 132 at the rod cap 136. The large-diameter rod transitions to the small-diameter rod 134. The rod (including the large-diameter rod 132 and the small-diameter rod 134) can be formed as a single workpiece or can be formed as several workpieces and then joined together using known machining methods. The rod can be formed of, for example, stainless steel or other types of steel or steel alloys (e.g., 316 stainless steel). However, any material having sufficient strength for mounting and under the system operating conditions is suitable. Supporting the large-diameter rod 132 and the small-diameter rod 134 is the anchor 140, which will be discussed further below.

[0051] The small-diameter rod 134 protrudes from the top of the thermal tap adapter 130 and passes through the top seal cap 252. The top seal cap 252 seals the system pressure against escape to the atmosphere and seals the small-diameter rod 134 with an O-ring or seal 254. The top seal cap 252 can be fastened by threading, pressing, welding, or other mechanical means sufficient to withstand the system pressure of the thermal tap adapter 130. The small-diameter rod 134 also protrudes through the collar 150, one or more springs 152, and the upper adjustment plate 154, each of which will be discussed further below. The bottom of the sensor head tube is sealed with the bottom seal cap 192.

[0052] Figure 4 Shows Figure 3 Cross-sectional view along section line IVI-IV. The sensor head 100 includes one or more field coils 180, for example made of copper wire, wound around the core 104. Other conductive materials sufficient to conduct the field coil current can also be used for the field coils 180. The field coils 180 are wound to be consistent with the system flow 172 ( Figure 1 ), that is, the area inside the field coils is generally parallel to the system flow 172. As Figure 4 shown, the cross-section of the field coils 180 shows lines going into and out of the page at the top and bottom of the core 104. The field coils 180 and the core 104 are within the sensor head tube 102 for protecting the internal components. The sensor head tube 102 can be made of any easily machinable material (including plastics and metals) that can withstand the system temperature and pressure. In one example, the sensor head tube includes acetal polymer. The head tube 102 can also be overmolded onto the coils 180 and the electrodes 105, 106, 107, 108, 109, 110. When the field coils 180 are excited with an alternating current (AC), an alternating magnetic field is generated (see, for example, Figure 28)。The conductive fluid flows through the magnetic field in the direction of system flow 172( Figure 1 ) According to Faraday's law, a conductor (i.e., the conductive fluid) passing through the magnetic field induces an electric potential and current indicative of the flow velocity. Voltages are measured between the top electrodes 105, 106 and the bottom electrodes 107, 108 respectively to determine the flow rate of the liquid.

[0053] Figure 5 Shows Figure 4 A cross-sectional view along section line V-V. As shown, the field coils are wound around and along the longitudinal axis 114 of the core 104. The reference electrodes 109, 110 project through the sensor head tube 102. The sensor head tube 102 can be sealed around the electrodes 109, 110 with O-rings / seals 111. The electrodes can be friction-fitted into the holes of the sensor head tube 102 or can be fixed using fasteners, adhesives or other known methods. The electrode wires 112 extend from the top of the sensor head 100 inside the sensor head tube 102 to each of the electrodes 109, 110 respectively. It should be noted that for simplicity, the electrode wires 112 are shown as a single cable. However, it should be noted that a single cable can include separate insulated conductors within the cable or the cable can be replaced by individual insulated conductors. The top electrodes 105, 106 and the bottom electrodes 107, 108 have the same configuration as the electrodes 109, 110, can also be sealed with O-rings / seals 111, and also have electrode wires 112. The electrode wires 112 run in the channel 350, which will be discussed below with reference to Figure 28 The electrode wires 112 can be held close to the center of the core 104 with spacers 116. The spacers can be any material having sufficient rigidity to hold the electrode wires 112 in place. Preferably, the spacers 116 are made of an insulating material such as plastic like ABS (acrylonitrile butadiene styrene) or nylon. The electrode wires 112 extend through the spacers 116 and are electrically connected to the electrodes 105, 106, 107, 108, 109, 110, which is not shown for simplicity. The electrode wires 112 can extend through the holes in the spacers 116 or through the gaps 118 between the cross-sections of the spacers 116 or through the formed channels. In another example, individual wires are replaced by circuit traces on a printed circuit board (PCB) or any other known method of electrically connecting the electrodes, which are placed and / or fastened to the core together with the channel 350. The electrode wires 112, together with the electrical connections (not shown) for the field coils 180, extend upward through the large diameter rod 132 and the small diameter rod 134 to the controller 300( Figure 1 ).

[0054] Figure 6 Shows Figure 4Detailed view of detail 6. In this view, a detailed view of the top electrodes 105, 106, O-ring / seal 111, spacer 116, and gap 118 is shown. Also shown is the rod cap 136 attached to the lower portion of the large-diameter rod 132. The rod cap 136 forms a threaded and snap-fit 200 connection with the sensor head tube 102, which will be discussed further below.

[0055] Figure 7 Shows Figure 4 Detailed view of detail 7. The bottom of the sensor head tube 102 is sealed with a bottom seal cap 192 and an O-ring / seal 255. Elastic feet 190 are on the bottom of the bottom seal cap 192, and the elastic feet 190 and the bottom seal cap 192 are fastened together by screws 194. Washers (not shown) may also be included to distribute the force. The elastic feet provide a surface that increases friction to better secure the sensor head 100 to the inner surface 173 of the flow tube 170 (e.g., to prevent rotation), and can also provide protection to the sensor head 100 and the flow tube 170 during installation and adjustment. Also shown are the bottom electrodes 107, 108, O-ring / seal 111, and spacer 116.

[0056] Figures 8 - 10 Perspective, side, and front views of the sensor head 100 without the sensor head tube 102 are shown. Figure 11 Shows Figure 8 Detailed view of detail 11. The field coils are wound to be consistent with the system flow 172, while the electrodes 105, 106, 107, 108, 109, 110 project perpendicular to the system flow 172.

[0057] Now referring to Figures 12 - 16 , the connection between the large-diameter rod 132 and the sensor head tube 102 will be discussed. Figure 13 Is Figure 12 Cross-sectional view of Figure 16 Is Figure 15 Cross-sectional view of Figures 12 - 16 along section line XIII-XIII, and

[0058] The end of the large-diameter rod 132 has both an axial threaded portion 202, lugs 204, and an O-ring / seal. It should be noted that Figures 12 - 16 and other figures show the axial threaded portion 202 and the lugs 204 on a separate mating end or rod cap 136, and the rod cap 136 is welded or otherwise attached to the end of the large-diameter rod 132. However, in an alternative, the connection features are formed directly on the large-diameter rod 132, i.e., there is no separate rod cap 136. For example, the end of the large-diameter rod 132 can be directly threaded or machined to provide the axial threaded portion 202 and the lugs 204.

[0058] On the inner wall of the sensor head tube 102, a head tube thread portion 208 is formed, and the head tube thread portion 208 mates with the thread of the shaft thread portion 202. Between the head tube thread portion 208 and the connection end of the sensor head tube 102, a lip 210 is formed. The size of the lip 210 is such that when the large diameter rod 132 and the sensor head tube 102 are fastened together by hand and cause a snap fit 200( Figure 16 ), the sensor head tube 102 and the lip 210 can deform sufficiently enough to be pressed against the lug 204. An O-ring 212 can be used to improve the snap fit. In particular, the joint includes both a thread and a snap fit, such that when the joint is being twisted, the thread helps to press the lip 210 against the lug 204. It should be noted that although the illustrated embodiment has a snap fit feature, other embodiments may not include a snap fit feature.

[0059] Threaded joints have a risk of rotating and backing out after installation. Using a threaded joint alone as part of an electromagnetic sensor head is challenging because the sensor must remain aligned after installation. Rotation after installation reduces accuracy and may result in accidental disassembly. Snap fits prevent axial movement but not rotation. They are also weaker in bending. Combining a snap fit with a threaded feature allows the meter to be assembled by hand rather than using a press; the joint only has to be rotated and the parts will pull themselves together. It also prevents flexure and increases the amount of torque required to remove the rod, thus helping to prevent accidental disassembly. However, as stated, a snap fit feature is not necessary to prevent disassembly or prevent rotation.

[0060] The threaded feature combined with the snap fit feature locks the sensor head 100 to the large diameter rod 132 by preventing backing out (i.e., reverse rotation). The threaded features (shaft thread portion 202 and head tube thread portion 208) pull the sensor head 100 onto the rod cap (large diameter rod 132). As the parts are pulled together, the snap fit 200 feature is engaged. Once the snap fit 200 has been engaged, it is not possible to easily disassemble the sensor head 100. Because the threaded forcing rotational movement also has axial movement, once the axial movement is locked down, the sensor head 100 cannot rotate without additional torque. This prevents the joint from backing out and separating during service, and also prevents rotation and misalignment of the sensor head 100 with respect to the rod. Once the snap fit 200 has been formed, a flat 220 or other mechanical key can be added to the top of the small diameter rod 134 that aligns with the electrodes 105, 107, 109, such that the direction of rotation of the sensor assembly 101 is known after insertion into the flow tube 170.

[0061] While individual threaded joints have advantages over snap-fit joints, such as reduced bending and load distribution over a greater area, a more rigid design and a more robust sensor head are generally achieved by combining threaded features with snap-fit joints. In one example, both snap features and threaded features can be produced on a lathe. This reduces machining costs by eliminating the need for a mill (as with other anti-rotation features).

[0062] Figure 17 A view is shown of the anchor 140, large diameter rod 132, and small diameter rod 134 in an unmounted position within the thermal tap adapter 130. The large diameter rod 132 transitions to the small diameter rod 134 at a rod transition 133. The rod transition 133 is shown tapering from the large diameter rod 132 to the small diameter rod 134. However, other transitions with sufficient strength can also be used. The anchor 140 is attached to both the large diameter rod 132 and the small diameter rod 134. The anchor 140 has a sufficient diameter to fit tightly within the thermal tap adapter 130. However, in one example, the anchor includes one or more holes within the anchor or a gap 142 around the anchor between it and the thermal tap adapter 130 to balance the pressure from the system flow 172 to the upper region 144. In one example, the gap 142 is advantageous because if the system flow 172 pressure is not equal to the upper region 144, then the entire system pressure must be overcome to insert the rod. However, if the system pressure is allowed to be balanced, then less force is required. The size of the gap 142 should be suitable to allow pressure balancing during standard installation maintenance. The gap size can vary depending on the system design pressure. For example, for the same balancing time, a larger gap may be required for a higher pressure system. As shown, the total area of the gap 142 ranges from about 0.180 in 2 to about 0.136 in 2 , which is about 16% of the total internal cross-sectional area of the exemplary thermal tap adapter 130. The anchor 140 can include friction-reducing workpieces, coatings, or inserts to reduce the sliding friction of the anchor 140 relative to the inner wall of the thermal tap adapter 130. For example, in an alternative embodiment, the anchor can include or acetal plastic sliders. However, other friction-reducing coatings that do not contaminate the system can also be used. The thermal tap adapter 130 and the upper region 144 are blocked from the atmosphere by a top seal cap 252 having an O-ring / seal 254.

[0063] Figure 18 is Figure 17Cross-sectional view along section line XVIII-XVIII. The large-diameter rod 132 and the anchor 140 are shown. The anchor 140 has a generally square profile with rounded corners 143. The rounded corners 143 ensure a tight fit with little room for lateral displacement, the importance of which will be discussed below. Although space is shown at the rounded corners 143 between the anchor 140 and the hot tap adapter 130, it is desirable to have no gap. However, due to tolerances in machining, a gap of approximately 0.0015 inches is provided to allow insertion. A gap 142 is provided to allow pressure equalization.

[0064] Figure 19 is Figure 17 Cross-sectional view along section line XIX-XIX. The small-diameter rod 134 and the anchor 140 are shown. Figure 19 Illustrates the hydromechanical benefit obtained by using an installation force for the small-diameter rod 134, which is opposite to the system pressure on the anchor 140 and the large-diameter rod 132. Each of the anchor 140 and the large-diameter rod 132 has a larger surface area than the small-diameter rod 134, that is, the anchor 140 has a larger cross-sectional surface area than the small-diameter rod 134 across each of their respective longitudinal axes. Due to the change in area from the small-diameter rod 134 where the installation force is applied to the anchor 140 and the large-diameter rod 132, an increase in mechanical benefit is achieved according to Pascal's law (or Pascal's principle). This mechanical benefit reduces the force required to insert the sensor head tube and thus also reduces the complexity and cost of the insertion mechanism, which will be further discussed below. Traditional plug-in sensors (hot tap sensors) trade off two factors in rod design: insertion force and flexural strength. The smaller the rod, the less force required to install the sensor. However, thin rods are affected by unwanted flexure, vibration, fatigue, and fracture. However, the example disclosed embodiments allow for the high strength (and low flexure) of a large rod, along with the low insertion force of a small rod.

[0065] Figure 20 and Figure 21 Shows an example sensor assembly in two stages of installation. First, with the valve 120 closed, the end of the hot tap adapter is connected to the valve 120 at the joint 131. The joint 131 can be any known mechanical device to engage a tube sufficient to withstand the pressure and mechanical stress at the joint, including but not limited to a threaded connection. Then, as referred to Figures 17 to 18As discussed, valve 120 is opened and the system pressure is balanced across the anchor 140. Before, after, or during pressure balancing, the rotation direction is initially checked and adjusted by rotating the small-diameter rod 134, which will be further discussed below. After balancing, the small-diameter rod 134 is pushed toward the flow tube 170, which pushes the anchor 140, the large-diameter rod 132, and the sensor head 100 into the flow tube 170. Following insertion, the rotation direction can be further verified and adjusted.

[0066] In prior art hot tap sensors, either the rod has a fixed diameter that is smaller than the inner diameter of its associated hot tap adapter. That is, it is not tightly mounted within its hot tap adapter, allowing mechanical flexure. Or, the rod has the length of the large-diameter hot tap adapter. In the small adapter configuration, all of the force of the system flow 172 acting perpendicular to the valve axis 114 is transferred from the entire length 146 of the axis to the top seal cap and results in a large moment arm, which increases the torque on the rod and the top seal cap. These prior small rod configurations not only result in excessive stress on the rod and top seal cap, but also a higher likelihood of inaccurate measurement results due to flexure of the sensor. In the exemplary sensor assembly 101 of the current application, the inner diameter of the hot tap adapter 130 is closely fitted to the anchor 140. During installation, the anchor 140 is inserted toward the flow tube 170 with the large-diameter rod 132, causing the anchor point or moment arm to dynamically shift toward the bottom of the flow tube 170. The anchor 140 has an insertion position closer to the tube 170 compared to prior sensors. Compared to prior sensors, the anchor 140 serves as the fulcrum for a reduced moment arm 148 at this time, which reduces the mechanical flexure of the sensor head 100. Additionally, as discussed above, the exemplary sensor assembly also has a reduced insertion force compared to a fixed large rod configuration.

[0067] Figure 22 and Figure 23 A perspective view and a front schematic view of an exemplary mechanical insertion device 260 are shown. The mechanical insertion device 260 can be used to manually insert the sensor head 100 into the bottom of the flow tube 170 and compress the spring 152. The mechanical insertion device 260 can be used for both gripping and inserting the small-diameter rod 134 and also for securing the rod against retraction after insertion. The mechanical insertion device 260 is shown as including an upper adjustment plate 154, which aids in axially aligning the small-diameter rod 134. The upper adjustment plate 154 is connected to the top seal cap 252 by means of threaded fasteners (e.g., bolts 264 that pass through 154 and are fixed by threads cut in the top seal cap 252). In an alternative, the bolts 264 can also be other threaded fasteners, such as a threaded rod and a wing nut or a combination of other types of nuts. Alignment of the upper adjustment plate 154 can be assisted by an alignment rod 266, which can also serve as a stop to prevent over-insertion.

[0068] When tightened, the upper adjustment plate 154 applies a force to the spring 152 which in turn applies a force to the collar 150 that is releasably tightened to the small diameter rod 134. This causes the rod to advance towards the flow tube 170. When the resilient feet 190 contact the bottom of the flow tube 170, the spring 152 will compress to prevent damage to the sensor head 100 while also applying a continuous pressure. Once fully seated and aligned, the nut 156 can be tightened to secure the small diameter rod 134 in place. The nut 156 can be a compression nut and can include a pressure sleeve as known in the art. The mechanical insertion device has the additional advantage over prior sensor assemblies in that the axial movement along the shaft 114 is independent of the rotational movement about the shaft 114. Thus, if the sensor head 100 is not properly radially aligned, then the rod 134 can be rotated, for example using the handle 268 ( Figure 25 ) during or after insertion. This allows for proper sealing of the mechanical assist thermal 130 independent of the sensor head alignment.

[0069] Figure 24 An alternative mechanical insertion device 500 is shown which can replace the mechanical insertion device 260 in all of the above-discussed embodiments, such as as Figure 31 shown. Returning reference Figure 24 , the mechanical insertion device 500 utilizes a threaded preload nut 504 as a single compression / rotation point which, in certain situations, can improve the alignment of the retaining rod 134 perpendicular to the flow tube 170 ( Figure 1 ). The preload nut 504 is releasably engaged with the thermal tap housing 506 which is used to protect the components inside the mechanical insertion device 500. The thermal tap housing 506 is also used to have threads 505 on which the preload nut 504 advances or retracts and is also used to provide a hard stop surface 514 which will be discussed below. A preload nut fixing screw 508 can be provided to prevent movement between the preload nut 504 and the thermal tap housing 506. A seal 516 is provided which can be, for example, an O-ring and is similar in design and function to the seal 254 ( Figure 17 ).

[0070] The mechanical insertion device 500 includes a main spring 510 having a spring constant between about 1000 in / lbs and about 1500 in / lbs (e.g., about 1375 in / lbs), such as, for example, a high tension spring. The main spring 510 provides a similar function to the spring 152 ( Figure 23 ). That is, the main spring 510 applies a continuous pressure downward when compressed so that the sensor head 100 ( Figure 1)Does not shift under high flow conditions or when the flow rate changes suddenly. The force of the main spring 510 is dispersed through the washer 512. A collar 520 located between the preload nut 504 and the thermal tap housing 506 or otherwise within the chamber defined by the preload nut 504 and the thermal tap housing 506 is releasably connected to the rod 134 and is used to transfer force between the main spring 510 and the rod 134. In one example, as shown, the collar 520 is releasably connected to the rod 134 using a collar screw 522 that is tightened around the rod 134. The collar screw 522 can be any suitable fastener such as a hex cut fastener. A positioning spring 518 is included for holding the position of the collar 520 while securing the collar screw 522. The ferrule 503 and the chuck nut 502 can be used to secure the rod 134.

[0071] As shown in Figures 25 - 27 , the rotational alignment about the axis 114 is assisted by a line-emitting light source (e.g., laser 310). The laser 310 is shown as being held in a laser mount 314 that is mounted on the small-diameter rod 134 and emits a light plane 316 that appears as a line on the flow tube 170 ( Figure 26 ). The line extends a certain distance from the axis 114, which allows the installer to be more precise in the axial rotation of the rod 134 compared to a person of ordinary skill in the art who aligns the rod 134 using previously known devices. For example, at a distance of two feet, a one-degree rotational error corresponds to a deflection of approximately half an inch. Thus, if the light plane 316 extends as a line that is about four to five feet away from the valve 120, a one-degree rotational error will be even more apparent. In one example, the line will be several feet long (e.g., 18 - 36 inches), but will vary depending on the height of the sensor and the particular laser. The longer the line, the more precise the alignment can be. Small differences in angle will be multiplied by the length of the line to easily identify and correct by rotating the small-diameter rod until the line is straight. Aligning the straight line along the center mark of the tube can further improve the accuracy. Then, the small-diameter rod 134 will be rotated until the laser line directly overlaps the marked line. This will further ensure precise alignment.

[0072] The laser 310 can be powered and controlled by the sensor assembly controller 300 via electrical and control lines (not shown), or it can be battery-operated and manually controlled. Prior to installation, the laser 310 and the laser mount 314 can each be rotationally aligned with the sensor head 100. To assist in the rotational alignment between the sensor head tube 102, the large-diameter rod 132, the small-diameter rod 134, the laser mount 314, and the laser 310, keys such as flats, notches, etc. can be machined in each individual component prior to assembling the sensor assembly. For example, the flat 220 ( Figure 15)。And in one example, the laser 310 and the laser mount 314 are permanently mounted to the small diameter rod 134.

[0073] The controller 300 is mounted on top of the small diameter rod 134. Each of the wires from the sensor head 100 travels upward inside the large diameter rod 132 and the small diameter rod 134 and is electrically connected to the controller 300 inside the housing 302. The controller 300 may also be adapted to control other sensor components. In such a configuration, the wire assemblies from other sensor components will also enter the housing 302. In an alternative embodiment, the controller 300 is mounted in another in-situ location and the wires are connected between the small diameter rod 134 and the controller 300.

[0074] Figure 28 A magnetic field density map is shown looking down on the core 104 such that the axis 114 is out of the plane of the paper. Note that the darker regions of the figure represent higher magnetic field intensities. In previous sensor designs, the electrode wires were shielded from the strong magnetic field generated by the coil by drilling a hole in the center of the core (along the axis 114) where the magnetic field was lowest and routing the wires through the hole. Shielding is beneficial so that the magnetic field does not induce stray currents in the electrode wires. However, this practice is expensive for the machine and time-consuming to install, especially in larger-sized cores. In the present exemplary embodiment, the core 104 has channels 350 machined in the sides where no coils are wound on them. The design of the channels 350 and the core 104 results in low magnetic field regions 352. Alternatively, the electrode wires 112 can be routed along the channels 350 within the low magnetic field regions 352. Spacers 116 ( Figure 7 ) can be added to help hold the electrode wires 112 within the low magnetic field regions 352. Fabricating the core is cheaper and easier to assemble in this regard compared to previous sensors.

[0075] Figure 29A and Figure 29BAn electrical schematic of the controller 300 and the sensor head 100 is shown. A power supply (PSU 450 supplies power to the coil drive circuit 462 and the microcontroller unit (MCU) 455. The MCU 455 includes outputs electrically connected to the user input / output (I / O) 430 and the user interface control and configuration module 440, which may include buttons, selector switches, displays, indicators, digital and / or analog interfaces, and alarms. The MCU includes an oscillator 460 (OSC) electrically connected to the coil drive circuit 462. Inside the coil driver circuit 462, there is an H-bridge 463 and a current regulator 464 to protect the field coil 180. If an additional sensor assembly is being controlled by the controller 300, additional H-bridges and current regulators may be included, if not already present within the selected H-bridge package. The H-bridge 463 energizes the field coil 180. The H-bridge 463 alternates the current output at the field coil 180 based on the OSC. Using alternating current (AC) prevents the permanent magnetization of the core 104 and also allows for the minimization of electrochemical and other effects at the electrodes by filtering out the DC voltage component, as discussed below.

[0076] Periodically, the electric potential (voltage) is read at the electrodes 105, 107, and the voltage generated according to Faraday's law indicates the velocity of the conducting fluid (e.g., water) passing through the magnetic field generated by the field coil 180. The electrodes 105, 107 may be electrically connected to the electrodes 106, 108 respectively, or may be independent. If they are separate, then additional input channels may be included in the controller 300 up to the analog-to-digital converter (ADC) 415, which may also have a multi-channel multiplexer feature. The voltage read at the electrodes 105, 107 is amplified at the amplifier 410.

[0077] When configuring the measurement amplifier 410, the gain directly affects how much DC error can be removed from the input signal. The gain should be selected such that the amplifier 410 operates within its linear region, but not so high as to reduce the input range to a narrow margin.

[0078] Integrator 412 provides negative feedback at 414 to AC-couple the signal. The resulting analog signal is then pre-filtered by a low-pass filter (LPF) 416 to filter out high-frequency noise and provide greater gain. Then, for final gain and proper biasing, the signal is sent to BIAS 418 to maximize the input resolution of the digital processing at ADC 415. The gain and filter stage LPF 416 are designed such that its bandwidth is significantly lower than the bandwidth of digital filter 417, ensuring that no aliasing of higher frequency signals will interfere with the output of digital filter 417. Further, the gain is adjusted to provide sufficient amplification to maximize the input range of the ADC. To avoid "clamping" of noise spikes that produce harmonic distortion of the signal, the output of the filter is biased to the half-supply point before being digitized.

[0079] The use of AC through the active circuitry eliminates the need to remove various stray DC potentials (e.g., electrochemical potentials at the electrodes). Instead of manually averaging several small points in the flow as done in prior sensors, the analog integration of the voltage across the entire tube diameter allows for infinite resolution sensing of the induced voltage without the weighting of various readings. Reading a single voltage by controller 300 greatly reduces the controller and sensor complexity and cost. The example embodiments also provide improved performance after elbows or perturbations, which contributes to a requirement for shorter straight runs. For example, in a straight tube, the velocity profile of the fluid flowing within the tube is generally parabolic, and the depth of the average velocity vector is approximately 1 / 8 of the inner diameter. Thus, prior sensors typically only measure the flow velocity at the 1 / 8 depth and assume that this flow velocity represents the velocity at other depths. However, changes in the straightness of the tube, such as elbows or other connections, disrupt the parabolic velocity profile and thus reduce the accuracy of those prior meters (depending on its position in the tube, the readings are either too high or too low). In contrast, the example flow sensors of the present application measure the induced voltage across almost the entire inner diameter such that those disturbances are sampled and included in the measurement result, and thus there is no strict requirement for straight tube runs. Overall, this reduces system complexity and increases measurement accuracy.

[0080] Most previously known electromagnetic flow meters use a DC-coupled amplifier as a pre-stage, which results in the need for complex switching circuit systems and precise timing techniques to process the input signal. This increases non-linear behavior and errors. This embodiment uses an AC-coupled pre-amplifier that allows for a linear intermediate amplifier and eliminates the need for complex switching circuit systems and precise timing techniques. AC coupling is achieved by applying negative feedback that integrates the input signal after the input stage of the measuring amplifier. The negative feedback eliminates DC offset while still providing high input impedance and high common-mode rejection. The AC-coupled signal, while retaining the common-mode rejection and high input impedance required for precisely sensing the signal of the electromagnetic flow meter. This AC-coupling scheme ensures that the signal leaving the first stage and pre-filtered (for anti-aliasing) and amplified will have a minimum amount of error contained in the signal, which increases the signal-to-noise ratio of the entire amplifier.

[0081] After amplification, the signal will be digitally rectified. Rectification and final filtering are implemented digitally with a custom algorithm that is designed to provide a very stable output that still responds quickly to the input, thereby increasing accuracy and performance, and filtered with an adaptive filtering algorithm, resulting in a more linear, precise, and accurate electromagnetic flow meter. The controller 455 precisely rectifies the signal and converts the square wave (generated by the alternating magnetic field) into a DC value proportional to the flow rate. The controller 455 is configured to "jump" if the input changes, thereby providing the benefits of a tight filter (stable output) and a loose filter (faster response). Further, the controller 455 auto-zeros itself by looking at two subsequent and opposite coil pulses, thus eliminating fabrication and installation steps and improving installation efficiency.

[0082] Once the signal has been converted from an analog signal to a digital signal at the ADC 415, the controller 455 auto-zeros the signal, converts the AC signal into a DC level proportional to the flow rate, and applies final filtering. To accomplish this function, the controller 455 monitors the input and output of the signal and looks at the input change equal to the current percentage. If the input "jumps", then the output follows, which in turn increases the responsiveness of the device. That is, the controller 455 looks at two consecutive pulses of opposite signs and uses this information to rectify the signal, largely filtering out the noise and adapting to large input changes.

[0083] Then, depending on the configuration at 420, the signal is output by the MCU as the resulting flow velocity, volume, or mass flow rate.

[0084] Referring Figure 30 , the installation of the sensor assembly 101 ([[]] Figure 24 ) including the mechanical insertion device 500 ([[]] Figure 1)Method 600. At step 602, apply a counterclockwise half turn or more to the chuck nut 502, collar screw 522, and set screw 508 to ensure that the rod 134, preload nut 504, and collar 520 can move freely. It should be noted that depending on the thread configuration and thread direction, the specific configuration may require more or fewer turns. At step 604, slide the sensor head 101 out a few inches from the thermal tap adapter 130 to ensure that it can move freely. If not, make additional adjustments to the chuck nut 502 and collar screw 522 to ensure that they are not tightened, and then retry. At step 606, the sensor head 101 is fully retracted into the thermal tap adapter 130. At step 608, the pipe threads of the thermal tap adapter 130 are covered with an appropriate pipe sealant, such as pipe tape. At step 608, with the holding valve 120 closed, the threaded end of the thermal tap adapter 130 is inserted into the valve 120 and secured, for example, by turning clockwise with an appropriate tool. At step 610, open the valve 120 and check for leaks at the threaded joint. If any leaks are present, then close the valve 120 and apply additional torque to the thermal tap adapter 130, and then open and check for leaks again.

[0085] At step 612, fully insert the preload nut 504 into the thermal tap housing 506 by rotating the preload nut 504 all the way clockwise (assuming right-hand threads). In one configuration, the lip 522 of the preload nut 504 should be flush with the top of the thermal tap housing 506 and no visible threads, and the preload nut 504 should not be turned any further. At step 614, turn on the laser 310 ( Figure 25 )(if included), and align the sensor assembly 101 with the flow tube 170, where the laser is pointed at the center of the tube in the expected downstream direction. At step 616, turn the preload nut 504 counterclockwise 1 1 / 4 turns out, and check the preload collar to ensure that it can move inside the housing. At step 618, use the handle 268 ( Figure 25 ) to slowly insert the sensor head 100 into the tube. At this step, if the rod 134 is pushed in, it should bounce gently on its positioning spring. At step 620, additional checks can be performed with a calibration for laser alignment if necessary. At step 622, while maintaining a downward force on the handle 268, use the window 530 ( Figure 31) or a fastener accessed through an opening in the hot tap housing 506 to fasten the collar screw 522. If necessary during this step, the collar 520 may need to be rotated within the hot tap housing 506 to obtain access to the head of the collar screw 522. At step 624, the preload nut 504 is rotated (clockwise if right hand threads are assumed) into the hot tap housing 506 until it bottoms out against the hard stop 514. This action preloads the main spring 510. The lip 524 of the preload nut 504 should be flush with the top of the housing 506 with no visible threads, and the preload nut 504 should not be rotated any further. At step 626, the chuck nut 502 is tightened. While tightening the chuck nut 502, alignment should be maintained by using the handle 268 as an aid to counteract torque. At step 628, the laser 310 is turned off and the set screw 508 on the side of the hot tap housing 506 is tightened. At step 630, proceed to the electrical connection to the controller 300( Figure 29A ).

[0086] It should be understood that the above description is merely illustrative of the present invention. Those skilled in the art can envision various substitutions and modifications without departing from the present invention. Accordingly, the present invention is intended to cover all such alternatives, modifications, and variations that fall within the scope of the appended claims.

Claims

1. A sensor assembly, the sensor assembly comprising: a rod; an elongated sensor head connected to the rod, the sensor head having a longitudinal axis, the sensor head including at least one top electrode and at least one bottom electrode, wherein the top electrode and the bottom electrode generally span the diameter of the flow tube; and a field coil configured to emit an alternating magnetic field when excited with an alternating current, wherein the field coil is wound around an axis antiparallel to the longitudinal axis of the sensor head; wherein the at least one top electrode and the at least one bottom electrode are configured to measure the voltage potential between the top electrode and the bottom electrode when the sensor head is inserted into the flow tube having an inner peripheral surface, wherein when the sensor assembly is inserted into the flow tube, the at least one top electrode is close to a first portion of the inner peripheral surface of the flow tube, and when the sensor assembly is inserted into the flow tube, the at least one bottom electrode is close to a second portion of the inner peripheral surface of the flow tube, and the first portion and the second portion are diametrically opposed.

2. The sensor assembly according to claim 1, wherein, The sensor head is attached to the rod via a threaded connection.

3. The sensor assembly according to claim 1, wherein, The sensor head is attached to the rod, and the rod has a large diameter portion and a small diameter portion, the large diameter portion being closer to the sensor head than the small diameter portion.

4. The sensor assembly according to claim 3, wherein, The rod includes an anchor fixed to the large diameter portion and the small diameter portion, the anchor having a greater cross-sectional area across its respective longitudinal axis compared to the cross-sectional area of the small diameter portion across its respective longitudinal axis.

5. The sensor assembly according to claim 4, wherein, The anchor having a greater cross-sectional area than the small diameter portion provides a hydromechanical benefit against forces applied to the small diameter portion.

6. The sensor assembly according to claim 4, wherein, The sensor assembly further includes a thermal tap adapter, and the outer diameter of the anchor is less than the inner diameter of the thermal tap adapter.

7. The sensor assembly according to claim 6, the sensor assembly further including a gap between the anchor and the thermal tap adapter to allow pressure equalization across the anchor.

8. The sensor assembly according to claim 6, wherein, The dimensions of the anchor assembly are such that the anchor assembly fits tightly within the thermal tap adapter to minimize lateral flexure of the sensor head when installed in the flow tube.

9. The sensor assembly according to claim 1, wherein, The field coil is wound around a first side and a second side of the core.

10. The sensor assembly according to claim 9, wherein, The core includes channels along a third side and a fourth side of the core, and the channels are parallel to the central longitudinal axis of the core.

11. The sensor assembly according to claim 9, wherein, The sensor head is molded and / or overmolded on the core and / or the electrodes.

12. The sensor assembly according to claim 10, wherein, The sensor head includes at least one electrode wire within the channel.

13. The sensor assembly according to claim 10, wherein, When the field coil is excited, a portion of the channel is in a lower magnetic field region.

14. The sensor assembly according to claim 12, wherein, The sensor head includes at least one spacer within the channel such that the electrode wire is between the spacer and the central longitudinal axis of the core.

15. The sensor assembly according to claim 1, the sensor assembly further including a mechanical insertion device, the mechanical insertion device including a top seal cap, an upper adjustment plate.

16. The sensor assembly according to claim 15, wherein, The rod passes through the top sealing cap and the upper adjusting plate, and the sensor assembly further includes a spring and a collar, and the spring and the collar each circumferentially surround the rod at least partially between the top sealing cap and the upper adjusting plate.

17. The sensor assembly according to claim 13, wherein, The rod can rotate before, during, and after inserting the sensor head into the flow tube and independently of a properly sealed hot tap adapter.

18. The sensor assembly according to claim 13, the sensor assembly further including a line emission light source attached to the rod and configured to emit a line onto the outer surface of the tube during and / or after inserting the sensor assembly into the tube.

19. The sensor assembly according to claim 1, wherein the sensor assembly further includes a controller, The controller is adapted to generate and an alternating current field coil current source, measure the voltage across the at least one top electrode and the at least one bottom electrode, and amplify and filter the resulting signal.

20. The sensor assembly according to claim 19, wherein The controller is further configured to monitor the input and output of the signal, and view two consecutive pulses with opposite signs, and use this information to rectify the signal, filter out noise, and accommodate large input variations.

21. The sensor assembly according to claim 1, the sensor assembly further including a mechanical insertion device including a pre-tightening nut and a hot tap housing.

22. The sensor assembly according to claim 21, the sensor assembly further including a collar and a positioning spring.

23. The sensor assembly according to claim 21, the sensor assembly further including a main spring.

24. The sensor assembly according to claim 1, wherein, The sensor head is sized such that when the sensor assembly is inserted into the flow tube, the sensor head contacts the second portion of the inner circumferential surface of the flow tube.

25. The sensor assembly according to claim 1, wherein, The field coil is wound such that a cross-section taken along its winding axis inside the field coil is generally parallel to the system flow.

26. The sensor assembly according to claim 1, wherein, The axis around which the field coil is wound is orthogonal to the longitudinal axis of the sensor head.

27. A method of inserting a sensor assembly into a flow tube, the method comprising: Fixing a pre-tightening nut into a hot tap housing; Applying a force to at least one handle connected to the rod to insert the sensor assembly into the flow tube; Fixing a collar to the rod, wherein the collar is between the pre-tightening nut and the hot tap housing; Tightening the pre-tightening nut into the hot tap housing until the pre-tightening nut bottoms out at a hard stop, wherein tightening the pre-tightening nut applies a force to the collar and the rod in the direction of the flow tube.

28. The method according to claim 27, wherein, Tightening the pre-tightening nut into the hot tap housing until the pre-tightening nut bottoms out at the hard stop of the hot tap housing further includes compressing a main spring, wherein the main spring transfers force from the pre-tightening nut to the collar.

29. The method according to claim 27, wherein, Fixing the collar to the rod further includes using a positioning spring to hold the collar in place.

30. The method according to claim 27, wherein The hard stop is part of the hot tap housing.

31. The method according to claim 27, the method further including tightening a chuck nut around the rod.

32. The method according to claim 27, the method further including aligning the sensor assembly with the flow tube using a line emission light source.

33. The method according to claim 27, wherein, The sensor assembly includes: A sensor head connected to the rod, the sensor head including at least one top electrode and at least one bottom electrode; and A field coil configured to emit an alternating magnetic field when excited with an alternating current; Wherein the at least one top electrode and the at least one bottom electrode are configured to measure the voltage potential of a conductive fluid when the sensor head is inserted into the flow tube, the flow tube having an inner peripheral surface.

34. The method according to claim 33, wherein, After tightening the preload nut, the at least one top electrode approaches a first portion of the inner peripheral surface of the flow tube, and after tightening the preload nut, the at least one bottom electrode approaches a second portion of the inner peripheral surface of the flow tube, and the first portion and the second portion are diametrically opposed.

35. The method according to claim 33, wherein, The sensor head is attached to the rod via a threaded connection.

36. The method according to claim 33, wherein, The sensor head is attached to the rod, and the rod has a large diameter portion and a small diameter portion, the large diameter portion being closer to the sensor head than the small diameter portion, and the large diameter portion being larger than the small diameter portion.

37. The method according to claim 36, wherein, The rod includes an anchor fixedly connected to the large diameter portion and the small diameter portion, and the anchor has a larger cross-sectional area across its respective longitudinal axis compared to the cross-sectional area of the small diameter portion across its respective longitudinal axis.

38. The method according to claim 37, wherein, The anchor having a larger cross-sectional area than the small diameter portion provides a hydromechanical benefit against forces applied to the small diameter portion.

39. The method according to claim 37, wherein, The sensor assembly further includes a thermal tap adapter, and the outer diameter of the anchor is less than the inner diameter of the thermal tap adapter.

40. The method according to claim 39, further comprising a gap between the anchor and the thermal tap adapter to allow pressure equalization across the anchor.

41. The method according to claim 39, wherein, The size of the anchor is such that the anchor fits tightly within the thermal tap adapter to minimize lateral flexure of the sensor head when installed in the flow tube.

42. The method according to claim 33, wherein, The sensor head includes a core, and the field coil is wound around a first side and a second side of the core.

43. The method according to claim 42, wherein The core includes channels along a third side and a fourth side of the core, and the channels are parallel to the central longitudinal axis of the core.

44. The method according to claim 42, wherein, The sensor head is molded and / or overmolded on the core and / or the electrodes.

45. The method according to claim 43, wherein The sensor head includes at least one electrode wire within the channels.

46. The method according to claim 43, wherein When the field coil is excited, a portion of the channel is in a lower magnetic field region.

47. The method according to claim 45, wherein, The sensor head includes at least one spacer within the channel such that the electrode wire is between the spacer and the central longitudinal axis of the core.

48. The method according to claim 33, further comprising a mechanical insertion device including a top seal cap, an upper adjustment plate.

49. The method according to claim 48, wherein, The rod passes through the top seal cap and the upper adjustment plate, and the sensor assembly further includes a spring and a collar, the spring and the collar each at least partially circumferentially around the rod between the top seal cap and the upper adjustment plate.

50. The method according to claim 40, wherein, The rod is rotatable before, during, and after inserting the sensor head into the flow tube and independently of a properly sealed thermal tap adapter.

51. The method according to claim 40 further comprises emitting a wire onto an outer surface of the tube during and / or after inserting the sensor assembly into the tube.

52. The method according to claim 33 further comprises generating an alternating magnetic field, measuring a voltage across the at least one top electrode and the at least one bottom electrode, and amplifying and filtering the resulting signal.

53. The method according to claim 52 further comprises monitoring inputs and outputs of the resulting signal, looking for two consecutive pulses with opposite signs, and using this information to rectify the signal and filter out noise.

54. The method according to claim 33 further comprises a mechanical insertion device, the mechanical insertion device comprising the pre-tightening nut and the thermal tap housing.

55. A method of inserting a sensor assembly into a flow tube, the method comprising: fixing a pre-tightening nut into a thermal tap housing; applying a force to at least one handle connected to a rod to insert the sensor assembly into the flow tube; fixing a collar to the rod, wherein the collar is between the pre-tightening nut and the thermal tap housing; tightening the pre-tightening nut into the thermal tap housing until the pre-tightening nut bottoms out at a hard stop; wherein fixing the collar to the rod further comprises using a positioning spring to hold the collar in place.

56. A method of inserting a sensor assembly into a flow tube, the method comprising: fixing a pre-tightening nut into a thermal tap housing; applying a force to at least one handle connected to a rod to insert the sensor assembly into the flow tube; fixing a collar to the rod, wherein the collar is between the pre-tightening nut and the thermal tap housing; tightening the pre-tightening nut into the thermal tap housing until the pre-tightening nut bottoms out at a hard stop; wherein the hard stop is part of the thermal tap housing.

57. A sensor assembly comprising: a sensor head including at least two electrodes, the sensor head being adapted to be inserted into a thermal tap adapter; a movable rod connected to the sensor head, the rod including a large-diameter portion and a small-diameter portion, the large-diameter portion being closer to the sensor head than the small-diameter portion; an anchor fixedly connected to the large-diameter portion and the small-diameter portion, the anchor having a larger cross-sectional area across its corresponding longitudinal axis compared to a cross-sectional area of the small-diameter portion across its corresponding longitudinal axis, and the anchor being sized to fit within the thermal tap adapter.

58. A sensor assembly comprising: a sensor head including at least two electrodes; a rod connected to the sensor head, the rod including a large-diameter portion and a small-diameter portion, the large-diameter portion being closer to the sensor head than the small-diameter portion; an anchor fixedly connected to the large-diameter portion and the small-diameter portion, the anchor having a larger cross-sectional area across its corresponding longitudinal axis compared to a cross-sectional area of the small-diameter portion across its corresponding longitudinal axis.

59. The sensor assembly according to claim 58, wherein, The anchor has a greater cross-sectional area across its respective longitudinal axis as compared to the cross-sectional area of the large-diameter portion across its respective longitudinal axis.

60. The sensor assembly according to claim 58, wherein, The dimensions of the anchor are such that the anchor fits securely within a hot tap adapter that is connected to the flow tube.

61. The sensor assembly according to claim 58, the sensor assembly further comprising a hot tap adapter connected to the flow tube.

62. The sensor assembly according to claim 61, wherein, The dimensions of the anchor are such that the anchor fits securely within the hot tap adapter.

63. The sensor assembly according to claim 61, wherein, The inner diameter of the hot tap adapter is approximately equal to the outer diameter of the anchor.

64. The sensor assembly according to claim 61, wherein, The inner diameter of the hot tap adapter is greater than the outer diameter of the anchor.

65. The sensor assembly according to claim 61, wherein, The inner diameter of the hot tap adapter defines a chamber therein, the chamber having a cross-sectional area across the longitudinal axis of the hot tap adapter, and the cross-sectional area of the anchor is less than the cross-sectional area of the chamber.

66. The sensor assembly according to claim 65, wherein, The cross-sectional area of the anchor is greater than or equal to approximately 84% of the cross-sectional area of the chamber.

67. The sensor assembly according to claim 61, wherein, The outer surface of the anchor includes at least one curved surface that conforms to the inner surface of the hot tap adapter.

68. The sensor assembly according to claim 58, wherein, The anchor comprises a plastic material.

69. The sensor assembly according to claim 58, wherein, The sensor head is attached to the rod via a threaded connection.

70. The sensor assembly according to claim 58, wherein, The anchor having a greater cross-sectional area than the small-diameter portion provides a hydromechanical benefit against forces applied to the small-diameter portion.

71. The sensor assembly according to claim 61, the sensor assembly further comprising a gap between the anchor and the hot tap adapter, the gap dimensioned to allow pressure equalization across the anchor.

72. The sensor assembly according to claim 60, wherein, The dimensions of the anchor assembly are such that the anchor assembly fits tightly within the hot tap adapter to minimize lateral flexure of the sensor head when installed in the flow tube.

73. A method of inserting a sensor assembly into a flow tube, the method comprising: Connecting a hot tap adapter to a valve that is connected to the flow tube; Opening the valve; Inserting a sensor head connected to a rod through the hot tap adapter and into the flow tube, wherein the rod includes a large-diameter portion and a small-diameter portion, the large-diameter portion being closer to the sensor head than the small-diameter portion; And Inserting an anchor into the hot tap adapter, wherein the anchor is fixedly connected to the large-diameter portion and the small-diameter portion, and the anchor has a greater cross-sectional area across its respective longitudinal axis as compared to the cross-sectional area of the small-diameter portion across its respective longitudinal axis.

74. The method according to claim 73, wherein, The anchor has a greater cross-sectional area across its respective longitudinal axis as compared to the cross-sectional area of the large-diameter portion across its respective longitudinal axis.

75. The method according to claim 73, wherein, The dimensions of the anchor are such that the anchor fits securely within the hot tap adapter.

76. The method according to claim 73, wherein, The inner diameter of the hot tap adapter is approximately equal to the outer diameter of the anchor.

77. The method according to claim 73, wherein, The inner diameter of the hot tap adapter is greater than the outer diameter of the anchor.

78. The method according to claim 73, wherein, The inner diameter of the hot tap adapter defines a chamber therein, the chamber having a cross-sectional area across the longitudinal axis of the hot tap adapter, and the cross-sectional area of the anchor is less than the cross-sectional area of the chamber.

79. The method according to claim 78, wherein, The cross-sectional area of the anchor is greater than or equal to approximately 84% of the cross-sectional area of the internal space.

80. The method according to claim 73, wherein, The short section is connected between the valve and the flow tube, and at least a portion of the anchor is retained within at least one of the thermal tap adapter, the valve, and / or the short section when the sensor assembly is in the fully inserted position.

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