In order to enable the precession vortex flowmeter to work in a normal state, the installation user must understand the specific structure, characteristics and flow signal conversion of the installed instrument, understand the role of each link in the signal transmission process, and install and use according to the product manual. Generally speaking, the following points should be paid attention to in the installation and use of precession vortex flowmeter.
1) Choose a reasonable installation site. The installation site should avoid strong electrical equipment, high-frequency equipment, and strong power switch equipment; avoid the effects of high-temperature heat sources and radiant heat sources; avoid the effects of high temperatures and strong corrosive atmospheres: avoid strong vibration and facilitate installation, wiring, and maintenance. Upstream and downstream of the sensor, vibration caused by excessively long pipes must be eliminated.
2) The instrument generally requires horizontal installation, and the flow direction of the measured fluid should be consistent with the arrow on the casing indicating the flow direction. It can also be installed vertically or at an angle. When measuring liquids, make sure that the sensor is always completely filled with liquid. In order not to affect the normal fluid transmission during maintenance, it is recommended to add a bypass in the installation section of the instrument.
3) The precession vortex flowmeter has lower requirements for straight pipe sections before and after. In principle, straight pipe sections are not required before and after the flowmeter, but generally require a 3D length straight pipe section in front of the meter and a 1D length straight pipe section behind the meter. Special circumstances require 5D and 3D lengths. When the bend radius of single or double bend pipe is greater than 1.8D, straight pipe sections are not required before and after the flowmeter.
4) Judgment pressure compensation can be used when measuring gas or steam.
5) When the measured fluid contains impurities, a filter or filter should be installed in front of the meter, but the requirements of the straight pipe section in front of the meter should still be ensured.
6} How to install the sensor when measuring a small amount of out-of-phase gas-liquid two-phase flow. When measuring liquids, there may be a small amount of gas phase in the pipeline, whose content does not exceed the specified gas-liquid two-phase fluid. In order to prevent gas from staying in the sensor, a gas separator must be installed. When measuring the gas, when the pipeline is condensed by the measured gas, and there is an unstable liquid phase in the gas that has not been removed, it is installed vertically to prevent the liquid from staying in the sensor. The sensor itself should have effective holding measures when measuring high and low temperature fluids.
7) The volume flow rate of the measured gas measured by the meter is the actual flow rate of the measured gas in the working state. If the actual flow rate is converted to the standard flow rate in the standard state, the formula can be calculated as follows, 4?p is the volume flow rate in the standard state; 4, is the volume flow rate in the working state; ho is the measured in the standard state Absolute pressure of the gas; To is the thermodynamic temperature of the measured gas in the standard state; household is the absolute pressure of the measured gas in the working state; T is the thermodynamic temperature of the measured gas in the working state; Z is the measured gas in the working state Compression factor.
8) When the pipeline is long and vibration may occur, fixing brackets should be installed upstream and downstream of the flowmeter to prevent pipeline vibration. Based on experience, flow measurement values ??are susceptible to air flow pulsation and pressure changes.
9) The volume flow meter coefficient K vn and mass flow meter coefficient K,,,o are determined by the calibration of the meter at normal temperature before leaving the factory. When the working condition of the instrument and the calibration state of the laboratory are quite different, the instrument coefficients K, and K'should be corrected, and the method of correcting the instrument coefficient is the same as the vortex flowmeter
Any type of measuring instrument has its particularity, and the intelligent precession vortex flowmeter is no exception. In order to make this kind of instrument better serve the flow measurement work, the practical experience from the production site shows that the following aspects should pay enough attention to the relevant management and use departments.
① Pay attention to instrument selection When the instrument type (for example, intelligent precession vortex flowmeter) has been selected, the choice of instrument specifications and supporting components is very important. In a word, you can only use it if you choose it. For this reason, two basic principles should be grasped in the selection process; namely: one must ensure the accuracy of use, and the other is to ensure production safety. To achieve this, three selection parameters must be implemented, namely, short-term and long-term large, small, and commonly used instantaneous flows (mainly used to select the size of the instrument), and the design pressure of the measured medium (mainly used to The nominal pressure level of the selected instrument), working pressure (mainly used to select the pressure level of the instrument pressure sensor).
② Perform calibration before use On the one hand, considering the current on-site verification of such instruments there are still some difficulties. In addition, if the purchase intention is to prepare this instrument for more important measurement occasions, such as high-flow trade measurement or measurement points where measurement disputes are prominent, and the application site does not have the conditions for online flow calibration, then In this case, it is too early to easily determine that all the performance of the table is qualified based on a piece of factory-provided certificate provided by the manufacturer at the time of purchase. Therefore, in order to ensure the reliability and accuracy of the measurement results of the instrument in the future work, it is necessary to send it to the department with the verification capability and qualification for a system verification within the full flow range before the formal installation.
③ Do a good job of process installation Although this kind of instrument does not have too many special requirements for process installation and use environment, any type of flow measurement instrument has such a commonality, that is, to avoid vibration and high-temperature environment as far as possible from the flow state interference components (Such as compressors, separators, pressure regulating valves, large and small heads, manifolds, elbows, etc.), keep the inner walls of the straight pipe sections before and after the instrument smooth and straight, and ensure that the measured medium is a clean single-phase fluid.
④ Strengthening the later management Although this kind of instrument has many features of automatic disposal and micro power consumption, it still needs to be strengthened after it is put into operation. For example, in order to ensure the accuracy and reliability of the instrument's long-term work (to avoid accidental outages and data loss), the system should be regularly calibrated (every 1'>~2 years), and the meter header data should be copied (daily or weekly) , Change media parameters (monthly or quarterly) and check battery status from time to time, check meter factor and lead seal, etc.
⑤ Pay attention to internal maintenance. If the measurement cavity and its components of the instrument need to be regularly inspected or cleaned due to dirty air quality or other reasons, then one must pay special attention: for the precession vortex flowmeter of the same specification, the vortex generation body The core components such as fluid and fluid can not be interchanged, otherwise, the metering coefficient of the instrument must be re-calibrated and the temperature and pressure sensors of the instrument must be corrected.
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