Yokogawa electromagnetic flowmeter selection has been used precautions:
The selection of Yokogawa electromagnetic flowmeters is best carried out by technicians familiar with on-site process conditions, and the appropriate diameter is selected according to the measurable flow range table in the selection data. Material selection is best determined by end users who are familiar with on-site process conditions.
First, select the flowmeter type:
1. Integrated type and separate type
The integrated type and the separate type have their own advantages, and the basic principles of selection are as follows: the separate type is generally used for occasions requiring range selection, batch control, frequent or long-term soaking in water and other functions. It is also used in harsher applications such as high temperature fluids, where there are sources of vibration and in explosive environments. In most cases, the integrated type and the separate type can meet the requirements of use.
2. General type and explosion-proof type
The user decides to choose the general type or the explosion-proof type according to the usage environment of the flowmeter.
Second, the diameter of the sensor and the diameter of the connected process pipeline
In general, considering the convenience of installation, do not choose reducers. But the premise is that the flow velocity in the flowmeter tube should be in the range of /s-10m/s. This choice is often suitable for newly designed projects. When choosing the flow rate, both the current working situation and the future situation when the equipment is running at full load should be considered. But sometimes the diameter of the sensor is also selected to be different from the diameter of the connected process pipeline.
For example: 1. The flow rate in the pipeline is low and the process flow is stable. In order to meet the requirements of the meter for the flow range, the flow rate is provided locally in the flowmeter.
3. For large-diameter electromagnetic flowmeters, the larger the diameter, the higher the price. When the flow rate in the pipeline is low and the process parameters are stable, a flowmeter with a smaller diameter can be selected, which not only makes the flowmeter run in a better condition. Working conditions, while reducing investment costs.
Third, the length of the straight pipe section D = the diameter of the flowmeter
1. Do not install anything that may interfere with the magnetic field, induced signal voltage and flowmeter velocity dispersion in the area near the flowmeter.
2. There is no need to use a straight pipe section at the downstream end of the flowmeter. However, if downstream valves or other fittings cause flow fluctuations, then a 2D-3D straight run must be used at the downstream end.
3. It is strongly recommended to install a valve at the downstream end, which can avoid flow fluctuations in the flow measuring tube, and can prevent the measurement from counting from the empty state of the tube.
Fourth, maintain a stable fluid conductivity
Avoid installing the flowmeter in locations where fluid conductivity is not uniform. If chemicals are injected near the upstream end of the electromagnetic flowmeter, the flow display may be affected. To avoid this, it is recommended that the chemical injection be redirected to the downstream end of the flowmeter. If it must be injected from the upstream end, use a long enough straight run (approximately 50D) to ensure that the fluid and chemical are well mixed.
Fifth, the installation location:
1. The pipeline must be completely filled with liquid. It is very important to ensure that the pipeline is always filled with liquid, otherwise the flow display will be affected and measurement errors will occur. The design of the road structure must ensure that the flow tube is always filled with fluid. Vertical installation is recommended when the fluid is divided or contains solid particulate deposits. However, when vertical installation is used, the direction of the fluid from bottom to top should be marked to ensure that the pipeline is filled with fluid.
2. Avoid air bubbles If there are air bubbles entering the flow measuring tube, the flow display will be affected, and measurement errors will occur. When the fluid contains air bubbles, the piping design must prevent the accumulation of air bubbles in the flow tube.
If there is a valve near the flow tube, try to arrange the tube upstream of the valve to avoid pressure reduction in the tube and thus avoid air bubbles in the flow tube.
3. Installation direction: If the electrode is perpendicular to the ground, the air bubbles gathered at the top or bottom will cause the measurement result to be wrong. Please install the junction box of the separate flow tube and the integrated converter on the top of the piping system to prevent water from entering.
4. It is recommended to use the gasket between the flow tube and the user's flange, use compressed non-asbestos fiber gasket, PTFE gasket or gasket with considerable elasticity. For GA, GC and GC, use rubber gaskets or other gaskets with considerable elasticity (such as jacketed Teflon rubber gaskets).
Six, order information:
1. When ordering a separate measuring tube and/or a separate converter, please give the specific flow range, unit, pulse equivalent, cumulative display pulse equivalent and other measuring tube ordering information. These parameters are set in the assembled converter before delivery.
2. If some options are set, the technical specifications related to these options need to be written when ordering.
3. Mark No.
Each marker number can be described by 16 alphanumeric (upper or lower case) numbers, as well as "-" and "" characters. On special request, the marking number can also be written on the nameplate and marking plate (if code SCT is selected). If the product is an integral type, the tag number is also written to the converter memory. For the HART protocol, there can only be a maximum of 8 characters. If the user wishes to change only the settings stored in the converter's memory, define the software tag number. If there is no marking number, the corresponding product does not have it at the time of delivery.
4. Flow range and unit
The value of the flow range is limited to five digits (maximum 99999), excluding the decimal point. Integral AXF products are set to the first range in the forward direction. The separate measuring tube is also set to the first range in the forward direction of the converter (AXFA11 or AXFA14) assembled with it. If the flow range and unit are not specified, the related products are delivered as 1m/s (ft/s).
5. Output pulse equivalent
If specified, the flow represented by each pulse must be set. Otherwise, the related products are all set to 0 pulses/second when they are delivered.
6, the accumulated value shows the pulse equivalent
If specified, the flow represented by each pulse must be set. Otherwise, the related products are all set to 0 pulses/second when they are delivered.
