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.
Turbine flowmeter composition
Turbine flowmeters are speed flowmeters, also known as impeller flowmeters. The impeller type flowmeter utilizes the relationship between the rotational angular velocity of the impeller placed in the fluid and the fluid flow velocity. By measuring the rotational speed of the impeller to reflect the volumetric flow rate of the fluid passing through the pipeline, it is a relatively mature high-accuracy instrument in the flowmeter. One. Turbine flowmeters generally consist of the following five typical parts:
The material of the body is generally steel or cast iron, and the ends are flanged. The small diameter gauge also has a threaded interface.
2. Measured component
The turbine has precision machined blades that together with a set of reduction gears and bearings form the measuring assembly. The two high-precision stainless steel permanent self-lubricating bearings that support the turbine ensure a long service life of the assembly. Turbine flowmeters can also be lubricated with an external lubricant pump, but be careful not to overdo it.
The following important information is available on the counter panel:
(1) Maximum working temperature and pressure:
(2) Metering and minimum and maximum flow levels
(3) Product model and number
(4) Explosion-proof grades and signs
(5) The equivalent of the fluid corresponding to the low frequency or high frequency pulse and the wiring method.
The rectifier is used to keep the fluid flowing through the turbine flow meter in a regular state, thereby eliminating the disturbance and having an unaffected effect on the metering. High metering accuracy.
5. Magnetic coupling transmission device
The device separates the counter portion in the atmospheric environment from the gas being measured and transmits the rotation of the measuring assembly to the counter.
Plug-in electromagnetic flowmeter features
Corrosion-resistant full stainless steel material, ABS full mold production probe structure is simple, firm, no moving parts, long service life, reliable measurement, strong anti-interference ability, small size, light weight, easy installation, small maintenance range, large measurement range, temperature-free measurement The influence of changes in density, pressure, viscosity, conductivity, etc., zero pressure loss can be installed and disassembled under continuous flow, which brings convenience to the user's maintenance. The manufacturing cost and installation cost are lower than the general electromagnetic flowmeter. It is especially suitable for large and medium-diameter pipeline flow measurement. It adopts advanced processing technology, solid-state packaging, vibration resistance and long life. It makes the meter have good measurement accuracy and stability. The flowmeter not only has 4-20mA current signal output, but also has 1-2000HZ frequency output digital communication output: RS485, RS232, HART, Modbus.