Installation requirements for vortex flowmeters
The vortex flowmeter is a kind of flowmeter that has high requirements on the flow field of the pipeline. In order to ensure the accuracy of the flowmeter measurement, the following items must be paid attention to when installing the vortex flowmeter on the pipeline:
1. Applicable working conditions
Vortex flowmeters are suitable for measuring gas, steam and liquid flow.
Flowmeters are especially suitable for measuring
1.1 Low viscosity cleaning liquid (<10cP)
1.2 Low viscosity hydrocarbons (<10cP)
1.3 water
1.4 Low Corrosive Chemicals
1.5 Saturated steam, superheated steam, including CIP and SIP applications in the food industry
For accurate measurement of volumetric flow, the medium must be full and have an ideal flow regime.Any vibration will distort the measured value, so the necessary measures should be taken to avoid the vibration of the pipeline.
2. Selection of the installation location of the flowmeter
2.1 Ambient temperature: The working environment temperature of the flowmeter is not lower than -20°C and not higher than +70C.If it is subjected to heat radiation from production equipment, heat insulation and ventilation measures should be taken.
2.2 Ambient air: Avoid installing the flowmeter in an environment containing corrosive gases. If it can only be installed in an environment containing corrosive gases, adequate ventilation measures must be provided.
2.3 When the temperature of the measuring medium is higher than 150°C, the meter head can be installed horizontally or vertically downward (see Figure 1), or choose a split form (also suitable for high-altitude, underground and other harsh environments) (see Figure 2), the maximum The extension distance is 10 meters.
2.4 When the flowmeter is installed in a vertical or inclined pipeline, the flow direction of the medium should be from bottom to top (see Figure 3)
2.5 It is best to install the flowmeter indoors. If it must be installed outdoors, measures should be taken to prevent moisture and sun.Special Note: Rainwater cannot flow into the electrical connector along the cable to cause damage to the circuit, and the electrical connector must be tightened, as shown in the figure below.
2.6 Mechanical vibration and shock. The structure of the flowmeter is solid and will not be damaged by vibration, but vibration will generate interference signals. If the vibration and impact on the pipeline are strong and the flow rate of the medium is low, the interference signal may be greater than the flow rate. signal, resulting in indication error.Therefore, the flowmeter should be installed in a place with small vibration and impact as much as possible, and the installation position should be under the vibration frequency of (5~20) HZ, and the vibration acceleration should not be greater than 1g or vibration reduction measures should be taken.For example, install a fixed support frame on the pipeline where the vibration source comes from where the flowmeter is installed.
2.7 In order to facilitate debugging, disassembly, and on-site maintenance of the flowmeter, there must be sufficient space around the installation flow, and the clear space above the meter head should be at least 0.5 meters (see Figure 4). If it cannot be guaranteed, the installation angle should be adjusted.
2.8 The upstream of the flowmeter should try to avoid installing regulating valves and half-open valves. It can be installed after 5D downstream of the flowmeter according to the process requirements (see Figure 5). If it must be installed upstream of the flowmeter, the upstream straight pipe section of the flowmeter should not be less than 50D.
2.9 Water hammer phenomenon: When measuring steam flow on a horizontal pipeline, the installation position of the flowmeter must not be at the lower part of the pipeline, because the lower part of a section of pipeline must be the place where condensation accumulates, and water hammer phenomenon is likely to occur during operation. It will seriously affect the normal measurement of the flowmeter, and may cause damage to the probe in severe cases. The flowmeter should be installed at a high place in the pipeline, and a steam trap should be installed at the low place in the front pipeline.
2.10 The wiring position of the flowmeter should be away from electrical noise, such as high-power transformers, electric equipment, etc.
2.11 There should be no radio transceiver near the installation point of the flowmeter, otherwise high-frequency noise will interfere with the normal use of the flowmeter
2.12 Signal transmission distance: The maximum transmission distance of the current output signal is 500 meters, and the maximum transmission distance of the pulse output signal is 1000 meters.
3. Pipeline installation and requirements (machinery industry standard ', number] B/T9249-2015)
3.1 The upstream and downstream of the flowmeter should be equipped with a certain length of non-blocking straight pipe section.The installation requirements of the straight pipe section are shown in the figure below
Note: 'D' represents the inner diameter of the flowmeter.
For example: install a flowmeter with an inner diameter D=50mm on a DN50 pipeline, and install it with the same diameter pipe as shown in D. The flowmeter should keep the upstream side 20D and the downstream side 5D as straight pipe sections (with no elbow joints, etc.), upstream Side 20D=20x50mm=1000mm, downstream side 5D=5x50mm=250mm, the total length of the straight pipe section is 1250mm.(When the installation of straight pipe section cannot satisfy the first 20D and last 5D, at least and must meet the first 10D and last 5D)
3.2 The upstream and downstream sides of the vortex flowmeter should have a straight pipe section with the same inner diameter as the vortex flowmeter.The upstream and downstream lengths of the straight pipe section vary with the pipeline conditions.There should be no valves or bypass pipes in the upstream and downstream straight pipe sections of the vortex flowmeter, and no flow regulating valve should be installed on the upstream side of the vortex flowmeter.
3.3 The vortex flowmeter can be installed horizontally, vertically or inclined on the pipeline, but when measuring liquid, the pipeline must be filled with liquid.Therefore, when installing a vortex flowmeter on a vertical or inclined pipeline, the flow direction of the liquid should be from bottom to top.The piping installation requirements for measuring gas and liquid are shown in the figure below.
It is strictly forbidden to install the flowmeter at a position lower than the pipe elbow, where condensate will accumulate2, and the condensate will cause cavitation and inaccurate measurement.Under certain conditions, the flowmeter can be damaged and cause the measured medium to leak.
It is strictly forbidden to install the flowmeter at a position higher than the pipe elbow D, there is a risk Q of air bubbles accumulating, air bubbles will cause pressure fluctuations and inaccurate measurements.
It is strictly forbidden to install the flowmeter in the upstream Q of the pipe 3 or the outlet pipe that flows vertically downward, as there is a risk of the pipe not being filled and the measurement will be inaccurate.
4. Flowmeter installation steps
4.1 Under the premise of satisfying the straight pipe section, cut a straight pipe length L to be M- (20+4) mm.
4.2 Assemble the flowmeter, gasket, flange and bolts into a complete set, put them into the cutout, and pay attention to the direction and angle of the arrow on the body of the flowmeter.
4.3 Spot welding positioning at the joint between the pipe and the flange.
4.4 Remove the bolts, remove the flowmeter and gasket, and weld the flange
4.5 Install the sealing gasket, install the flowmeter, and tighten the bolts
5. Problems that should be paid attention to during installation
5.1 The flow direction of the measured medium must be consistent with the flow direction arrow mark on the flow meter flow body;
5.2 The detection amplifier and the flowmeter are matched according to the measuring range and nominal diameter, and cannot be interchanged.When installing the card-mounted flowmeter, the concentricity between the pipeline and the flowmeter body can be ensured through the special concave surface, and the gasket should not penetrate into the pipe; 5.3 The inner diameter of the pipeline where the flowmeter is installed must be consistent with the inner diameter of the flowmeter. Usually the inner diameter of the pipeline is the same as that of the vortex street. The error of the inner diameter of the flowmeter meter should be S2%, otherwise the piping should be re-piped:
5.4 The inner diameter of the sealing gasket on both sides of the vortex flowmeter must be consistent with the inner diameter of the flowmeter, and it is strictly forbidden to use gaskets smaller than the inner diameter of the flowmeter.When installing the flange connection type vortex flowmeter, prevent the gaskets on both sides from entering the pipeline, otherwise the flowmeter will not work normally;
5.5 When installing the flowmeter, it is forbidden to carry the flowmeter directly on-line full welding, otherwise the heat generated during full welding will damage the meter and electronic components of the flowmeter:
5.6 When measuring high-temperature media, do not wrap the sensor connecting rod with heat-insulating material;
5.7 Before installing the flowmeter, the debris in the pipeline should be strictly removed, such as: debris, welding slag, stones, dust, etc., to avoid blockage after flow through or debris hitting the sensor at high speed in the pipeline to cause failure;
5.8 When measuring steam, if the steam is used for the first time or the steam pipeline has been shut down for a long time, the valve must be opened slowly and slightly. After the valve, the temperature of the pipeline rises to the steam temperature, and after the condensed water in the pipeline is basically discharged, the pressure on both sides of the valve is basically the same. , and then slowly open them all.Otherwise, it is easy to cause the rapid expansion of the pipeline, damage the pipeline support and flow meter, and act at the same time as the water hammer, with serious consequences.
