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A flow meter is an instrument that indicates the flow rate being measured and/or the total volume of fluid over a selected time interval; it is also an essential device for measuring the flow of liquids and gases. Surely, most people have come across many different types of flow meters in their daily lives. The correct installation method is very important for flow meters. Below, we will learn about the key installation points for eight common types of flow meters through this article. The history of flow measurement in flowmeters dates back to ancient hydraulic engineering and urban water supply systems. During the time of Caesar in ancient Rome, orifice plates were already used to measure the amount of drinking water available to the residents. Around 1000 BC, ancient Egypt used weirs to measure the flow rate of the Nile River. China’s famous Dujiangyan irrigation project makes use of water level observations and flow volume measurements at the Baopingkou site. In the 17th century, Torricelli laid the theoretical foundation for differential pressure flow meters, which was a milestone in flow measurement. Since then, the prototypes of many types of flow measurement instruments from the 18th and 19th centuries began to emerge, such as weirs, tracer methods, pitot tubes, Venturi tubes, volumetric, turbine, and target flow meters. In the 20th century, the sharp increase in the demand for flow measurement in process industries, energy metering, and urban utilities led to rapid development of measuring instruments. The significant advancements in microelectronics and computer technology greatly facilitated the upgrading of these instruments, resulting in the emergence of numerous new types of flow meters. To date, it is said that hundreds of flowmeters have been introduced to the market, and many difficult problems encountered in field use are expected to be solved. China started working on modern flow measurement technologies relatively late, and the flow meters required in the early stages were all imported from abroad. 01. Electromagnetic flowmeter: The measurement principle of an electromagnetic flowmeter does not depend on the characteristics of the flow rate; any turbulence or vortices that occur in areas outside the measurement zone have no impact on the measurement. Installation tips A: The installation location should not have any significant sources of vibration, and reinforcement measures should be taken to stabilize the pipes near the instrument ； B. It cannot be installed near devices that generate strong magnetic fields, such as large transformers, motors, and pumps, to avoid interference from electromagnetic fields ； C. When connecting the sensor to the pipeline, it is necessary to ensure full pipe operation; vertical installation is preferred ； D. The transmitter housing can be grounded by connecting it to the nearest grounding grid ； The shielded cable (separate type) is connected according to the instructions, while the signal cable (leading to the system) has its shielding layer grounded at one end ； The short-circuit ring that connects the measuring sensor to the pipeline needs to be grounded; the grounding resistance should be less than 10 ohms, and it cannot share the same grounding system as the electrical system ； E. There should also be a certain length of straight pipe upstream of the flowmeter sensor, generally ranging from 5D to 10D. The installation details are as follows: If there are steady-state eddies within the measurement area, it will affect the stability and accuracy of the measurements. In such cases, the length of the straight sections before and after the measurement area can be increased, a flow stabilizer can be used, or the cross-sectional area at the measurement point can be reduced to stabilize the flow velocity distribution. The flow meter can be installed horizontally or vertically, but care should be taken to prevent deposits and bubbles from affecting the measuring electrodes; it is advisable to keep the electrodes horizontal along their axis. When installed vertically, the fluid should flow from bottom to top. Sensors cannot be installed at the highest point of the pipeline, as bubbles tend to accumulate there. Ensure that the pipeline is filled with the fluid being measured at the time of testing by the flow sensor, and that there is no condition of an unfilled pipeline. If the pipeline is not fully filled or there is a vent at the outlet, the sensor should be installed on a siphon tube. The standard straight pipe section requirements for electromagnetic flowmeters are 10D in front and 5D behind; different requirements apply in the presence of bends or valves. Reason for grounding an electromagnetic flowmeter: The measuring electrodes inside an electromagnetic flowmeter are situated in a direct current or alternating current field; if their environment is not effectively shielded from interference, it can cause serious disturbances to the measurement. Whether the sensor housing is grounded or not has a direct impact on the accuracy and stability of measurements. The grounding wire must not transmit any interference voltages; therefore, electromagnetic flowmeters require a very reliable grounding system with proper grounding shielding, otherwise interference currents will be generated. Benefits of grounding an electromagnetic flowmeter: If the pipeline connected to the flowmeter is insulated (relative to the medium being measured), a grounding ring is required; its material should be selected based on the corrosiveness of the medium being measured. For measurement sensors with a PTFE lining, a grounding ring must be used to ensure their proper operation. 02. Ultrasonic flow meters: Ultrasonic flow meters are also quite common types of flow meters. Their installation is the simplest and most convenient among all flow meter installations – one only needs to select an appropriate measurement point, enter the pipeline parameters at that point into the flow meter, and then fix the probe to the pipeline. Installation tips: 1. Choose pipe sections that are made of materials with uniform density and are filled with fluid, and that facilitate ultrasonic transmission, such as vertical or horizontal pipe sections. 2. The installation location should be in a section of straight pipe with a length of more than 10 times the diameter of the straight pipe upstream, and more than 5 times that diameter downstream, and such a section should contain no valves, elbows, diameter changes, etc.; the installation point must be far enough away from sources of interference such as valves, pumps, high-voltage electricity, and frequency converters. 3. Avoid installing at the highest point of the piping system or on vertical pipes with a free outlet. 4. For pipes with openings or that are half-full, the flow meter should be installed at the U-shaped section. 03. Vortex flow meter: The main installation requirements for vortex flow meters relate to the requirements for straight pipe sections and pipeline vibration; there should be long straight pipe sections on both the upstream and downstream sides of the vortex flow sensor ； The pipeline must not vibrate; if vibration occurs, fixing devices need to be installed on both sides of the flow meter. Installation tips: For vortex flowmeters, when measuring gas flow, if the gas being measured contains a small amount of liquid, the flowmeter should be installed at a higher position in the pipeline. When measuring liquids, if the liquid being measured contains a small amount of gas, the flow meter should be installed at a lower point in the pipeline. Pressure and temperature measurement ports: When pressure measurement is required, the pressure measurement port should be placed 2 to 7D downstream of the flow meter. When temperature measurement is required, place the temperature sensor between 1 and 2D downstream of the pressure measurement point. Pipe support: Install the flow meter in a location where the vibration acceleration is less than 20 m/s2. When pipe vibration is excessive, the pipes should be installed with reinforcing supports. Sealing gasket: The sealing gasket must not protrude into the pipe, as this will lead to unacceptable errors. 04、Key installation points for turbine flowmeters: Turbine flowmeters can be installed horizontally or vertically; when installed vertically, the flow direction must be upward. The pipeline should be filled with liquid, without any bubbles. During installation, the flow direction of the liquid should be consistent with the arrow indicating the flow direction on the sensor housing. During installation, the fluid in the pipeline must fill it completely to ensure accurate measurement. There should be a straight pipe section of at least 10 times the nominal diameter length upstream of the flow meter, and at least 5 times the nominal diameter length downstream. Its inner wall must be smooth and clean, free from defects such as dents, deposits, or peeling. The axis of the sensor pipe should be aligned with that of the adjacent pipe, and the gaskets used for sealing the connection must not extend into the interior of the pipe. The requirements for straight pipe sections under different conditions are shown in the figure below. At the same time, during installation, bubbles inside the pipeline should be avoided, as this can affect the accuracy of the measurements. 05、VeriBa flow meter: The VeriBa flow sensor is a flow sensor designed based on the differential pressure principle and an insert-type installation method. Structural features: scientific cross-sectional shape, unique anti-clogging design, roughened sensor surface, and anti-sediment channels. Key installation points: Basic installation method for horizontal pipes. For horizontal pipes, it is recommended to install the device within an angle of 160 degrees above the pipe when measuring gases; this is especially true for gases containing a large amount of water vapor, as we only recommend such an installation method in such cases ； When measuring liquids, it is recommended to install it within a 160-degree range below the pipeline; this is especially true for liquids containing a large amount of gas, as we only recommend such an installation in such cases ； One thing to note, however, is that for those liquids that vaporize very easily, such as liquid olefin-based media, the insertion direction during installation should be in the same direction as the gas, above the pipeline. When measuring steam, it is recommended to install the sensor within 160 degrees below the pipeline, and to position it at the highest point of the entire measurement setup. The basic installation method for vertical pipes: Theoretically, vertical pipes can be installed within 360 degrees. For wet gases containing a large amount of moisture, it is recommended to tilt the sensor upward by 5 degrees during installation, as shown in the figure on the left. For liquids containing a large amount of gas, it is recommended to tilt the sensor downward by 5 degrees during installation, as shown in the figure on the right. For steam, it is recommended that the sensor be installed at a 5-degree downward angle, as shown in the figure on the right, and it should be positioned at the highest point in the entire measurement system. Minimum straight pipe length required for Veliba installation – 2D installation after the elbow is as shown in the figure. When the straight sections upstream and downstream of the pipe are not long enough, we recommend installing a Weiba at a distance of 2 times the inner diameter of the pipe behind the elbow, as the fluid profile behind the elbow is complex and it is necessary to make appropriate adjustments to the flow coefficient K. After adjusting the K coefficient, the measurement accuracy is ±3%, while the repeatability accuracy is ±0.3%. 06. Key installation points for rotameters: 1. Installation direction of the instrument – The vast majority of rotameters must be installed vertically in pipes free from vibration; there should be no significant tilt, with the fluid flowing through the instrument from bottom to top. The angle between the center line of the rotameter and the vertical line generally does not exceed 5 degrees; for instruments with high precision (grade 1.5 or higher), θ ≤ 20°. If θ=12°, an additional 1% error will occur. There is no strict requirement for the length of the straight upstream pipe section for the instrument, but some manufacturers require a length of (2-5)D; however, this is not really necessary. 2. For installation with dirty fluids, a filter should be installed upstream of the instrument. When a metal tube rotameter with magnetic coupling is used for fluids that may contain magnetically susceptible impurities, a magnetic filter should be installed in front of the instrument. It is necessary to keep the float and cone tube clean, especially in instruments with small diameters; the cleanliness of the float significantly affects the measurement values. 3. Installation of rotameters to expand their measurement range: If the required flow rate range is wide, with a range exceeding 10, two floats of different shapes and weights can be used in a single instrument. For low flow rates, the reading is taken using the lighter float; once the float reaches the top, the reading is taken using the heavier float. This allows the measurement range to be expanded to 50–100. 4. Installation of rotameters in pulsating flow: The pulsations in the flow itself, such as the presence of reciprocating pumps or control valves upstream of the location where the instrument is to be installed, or large load variations downstream, require that the measurement location be changed or that corrective measures be taken in the pipeline system, such as installing a buffer tank ； If the oscillation is caused by issues with the instrument itself, such as too low gas pressure during measurement, valves upstream of the instrument not being fully open, or the control valve not being installed downstream of the instrument, appropriate measures should be taken to address these problems, or an instrument equipped with a damping device should be used instead. 5. To drain the liquid from a rotameter, use the gas inside the instrument. For angular metal rotameters whose gas inlets and outlets are not aligned in a straight line, when using them with liquids, it is important to check whether there is any air remaining in the extension tube that affects the displacement of the float; this air must be completely drained ； If the liquid contains tiny bubbles, they tend to accumulate inside the casing during flow, so it is even more necessary to vent regularly. This is even more important for small-diameter instruments; otherwise, it has a significant impact on the flow reading. 6. The flow rate value of the rotameter requires necessary conversion. Unless the instrument is custom-made by the rotameter manufacturer based on parameters such as the density and viscosity of the medium, liquid-based instruments are usually calibrated using water, while gas-based instruments are calibrated using air, with the values set at standard engineering conditions. When the fluid density, gas pressure, and temperature under operating conditions do not match those used for calibration, necessary conversions must be made. The conversion formulas and methods are detailed in the manufacturer’s instructions for rotameters. 07. Installation requirements for orifice plate flow meters: 1. Before installation, the orifice plate should be checked to ensure that its serial number and dimensions meet the requirements of the pipeline installation location. 2. For a newly installed piping system, the orifice plate must be installed after the pipes have been flushed and cleaned. 3. Pay attention to the installation direction of the orifice plate: the “+” sign should face the flow direction. 4. The center of the orifice plate should coincide with the centerline of the pipeline, and the concentricity error must not exceed the value of 0.015(1/β – 1). 5. When installing the orifice plate in the pipeline, it is necessary to ensure that its end face is perpendicular to the pipeline axis, with the perpendicularity error not exceeding ±1°. 6. The gaskets used to clamp the orifice plate (including those between the annular chamber and the flange, and between the annular chamber and the orifice plate) must not protrude into the inner wall of the pipeline after clamping. 7. The installation site of the orifice plate must be airtight; no leakage is allowed. Therefore, the installation work must be carried out before pipeline pressure testing. 8. The pressure guide pipe shall be installed vertically or at an inclination, with the inclination ratio not being less than 1:12. For fluids with higher viscosity, the inclination should also be increased. When the distance over which the differential pressure signal is transmitted exceeds 3 meters, the pressure guide pipe should be inclined in segments, with gas collectors and settlers installed at each high point and low point respectively. 9. To avoid distortion in the transmission of differential pressure signals, the positive and negative pressure conduits should be laid as close to each other as possible; anti-freezing measures should also be taken in cold regions. Electric heating or steam insulation can be used, but care must be taken to prevent the medium under measurement from overheating and vaporizing, which could generate gas in the pressure guide tube and cause false pressure readings. 10. When the orifice plate is installed on a vertical main pipeline, the location of the pressure tapping point can be chosen arbitrarily within the plane of the pressure tapping device. The orifice plate is installed in a horizontal or inclined main pipeline, with the pressure tapping locations as shown in Figure 4. 11. The pressure guiding tube shall be manufactured from materials resistant to pressure and corrosion, selected according to the properties of the medium being measured; its inner diameter must not be less than 6 millimeters, and its length should preferably be within 16 meters. 08. Installation requirements for mass flow meters: 1. The installation location should be chosen to avoid electromagnetic interference. The installation locations of sensors and transmitters, as well as the routing of cables, should be kept as far away as possible from devices that generate strong electromagnetic fields, such as high-power motors, transformer installations, and frequency conversion equipment. 2. The mass flow sensor should be installed such that its flow direction indicator is in line with the flow direction of the fluid. And ensure that the arrow points in the same direction as the flow direction configured inside the transmitter. (Note: The mass flow meter can be used in both directions. If the installation direction is opposite to the actual flow direction, modify the flow direction configuration within the transmitter. ) 3. A mass flow meter is a flow measurement device that operates on the principle of vibration in the measuring tube; therefore, when installing the sensor, it is necessary to provide solid support near the flanges on both sides of the process pipelines (at a distance of about 2 to 10 times the diameter of the tube), in order to prevent vibrations from occurring in the meter and the associated pipelines. If intense pipeline vibration is unavoidable, it is recommended to isolate the pipeline system from the instrument sensors using flexible pipes. 4. Since the mass flow meter operates on the principle of the Coriolis force, gravity is taken into account to avoid its impact on measurement accuracy. Whether the measurement tube of a mass flow meter is installed vertically or horizontally, it should be kept as vertical or horizontal as possible with respect to the ground level. 5. During installation, the flange surfaces should be parallel to each other, and the centers of the two flanges should lie on the same axis to avoid the generation of additional stress. It is strictly prohibited to use sensors to force straighten the upstream and downstream process pipelines, as this will affect the measurements and even damage the sensors. 6. It is recommended to install stop valves and bypasses on the pipes upstream and downstream of the sensor to facilitate zero adjustment, routine maintenance, and to ensure that the sensor remains in a fully filled state even when it is not in use. Mass flow meters used in trade handover scenarios do not require a bypass. Use the control valve downstream of the flow meter for flow control. 7. The installation orientation of the sensor must ensure that the medium to be measured can completely fill the sensor. The liquid must not trap air. For gases, there should be no accumulation of liquid; for viscous, dirty, or high-viscosity media, it should be easy to empty them (low-point valves can also be installed on both sides as needed). 8. For newly installed pipelines or those that have not been in use for a long time and are just being put into operation, the entire pipeline must be purged before installing the mass flow meter (especially the upstream section of the pipeline), to ensure that no weld slag or debris remains inside it. 9. It is recommended to install a filter at the inlet of the mass flow meter during its installation. When measuring liquids, it is recommended to keep the measuring tube vertical downward (as shown in the figure below) ； When measuring gases, it is recommended to keep the measurement tube vertically upward (as shown in the figure below) ； When measuring particles, it is recommended to use a flag-style installation (as shown in the figure below). Through the introduction of the aforementioned flow meters, the installation methods for flow meters under common operating conditions are now fairly clear. For flow meter installation in complex operating conditions, it is necessary to analyze each situation on its own; accumulating extensive experience is the most important factor in solving such problems.