Vortex flowmeter common fault
1. The measurement range of the vortex flowmeter is large, generally 10:1, but the lower limit of measurement is limited by many factors: Re>10000 is the most basic condition for the operation of the vortex flowmeter. In addition, it is also responded by the vortex. The signal, the vortex frequency f is also small, and it also makes signal processing difficult. The upper limit of measurement is the frequency response of the sensor and the frequency limit of the circuit. Therefore, the flow rate range must be calculated and calculated according to the flow rate of the fluid. The environmental conditions on the site are complicated. In addition to the conditions such as ambient temperature, humidity, and atmosphere, electromagnetic interference should also be considered.
2, vibration is also a big enemy of this type of instrument. Therefore, care should be taken to avoid mechanical vibrations, especially the lateral vibration of the pipe (perpendicular to the pipe axis and the vertical vortex generating body axis). This effect cannot be suppressed and eliminated in the design of the flowmeter structure. Since the vortex signal is equally sensitive to the influence of the flow field, it is not suitable for the length of the straight pipe section to ensure the flow conditions necessary for stabilizing the vortex street. Even the capacitive and ultrasonic type with strong anti-vibration performance guarantees that the fluid is a fully developed one-way flow, which is not negligible.
The medium temperature also has a great influence on the performance of the vortex flowmeter. For example, the pressure stress type vortex flowmeter cannot be used for a long time at 300 °C, because its insulation resistance is rapidly reduced from 10-100 MΩ at normal temperature to 1-101 Ω, and the output signal is also small, resulting in deterioration of measurement characteristics. In the measurement system, the sensor and the converter should be installed separately to avoid long-term high temperature affecting the reliability and service life of the instrument. The vortex flowmeter is a relatively new type of flowmeter. It is in the development stage and is not very mature. If it is not properly selected, the performance will not work well. Only after reasonable selection and correct installation, it is necessary to carefully and regularly maintain during the use process, accumulate experience, improve the predictability of system failure and the ability to judge and deal with problems, so as to achieve satisfactory results.
Ultrasonic flowmeter performance characteristics
Measuring liquid: single fluid such as water, seawater, alkali, etc., turbidity less than 10000ppm, particle size less than 1mm
Pipe material: Ultrasonic penetrating full pipe such as steel, cast iron, PVC pipe, dense texture, no serious corrosion and scaling, allowing thin layer of dense lining
Pipe lining material: rubber, epoxy asphalt, fiberglass, mortar, etc., or unlined
Pipe diameter range: DN15mm~6000mm, plug-in sensor for pipe diameter DN25mm~6000mm
Flow rate range: -32m/s~0~+32m/s, bidirectional flow
Accuracy: ±1.0% of displayed value (under standard conditions). Configure plug-in sensor accuracy up to 0.5%
Linearity: 0.5%.
Signal output: 4-20mA or 0-20mA RS-485
Sensor: It is divided into external clip type and plug-in type. The standard configuration is clip-on. The maximum operating pressure of the plug-in sensor is 3 MPa.
Straight pipe length: upstream >10D, downstream >5D from pump outlet >30D (D: pipe diameter)
Display mode: 2*20 character LCD display with LED backlight
Protection level: IP65
Explosion-proof grade: ExdIIBT4
Fixed ultrasonic flowmeter power supply: AC110V, AC220V, DC8~36V or AC7~30V
Ambient temperature / humidity: Host -20 ° C ~ +80 ° C; sensor -20 ° C ~ +80 ° C or -20 ° C ~ +160 ° C optional, the sensor can be immersed in water, water depth less than 2m.
Battery powered electromagnetic flowmeter features
1. Micro power consumption design, five 3.6V lithium batteries, continuous operation for 5~10 years, and easy to replace the battery.
2. The display adopts LCD large-screen liquid crystal display, which can display multiple flow parameters such as instantaneous flow rate, flow rate (pipe pressure), cumulative total amount of forward and reverse, and alarm prompt.
3. There are no movable and resistance parts in the measuring tube, no entanglement or clogging phenomenon, almost no pressure loss, and long-term reliable and continuous work.
4. Wide measurement range: The flow rate measurement range can reach 0.05m/s~10m/s.
5. High measurement accuracy: ±0.5% ~ ±1.0%.
6. Measurement stability: The measurement accuracy is not affected by changes in physical parameters such as temperature, pressure, viscosity and density of the measured medium.
7, with pulse output and GSM wireless data remote transmission.
8, with data storage function, up to 1000 groups of traffic data can be saved, and the data storage time can be arbitrarily set and data query.