In modern industry, vortex gas flow meters are highly regarded for their excellent suitability, especially for flow measurement of gases, liquids and steam. However, it is not easy to select a vortex flow meter that meets your needs; it involves weighing multiple factors. This article will provide you with a set of systematic vortex flowmeter selection guide, to help you make an informed choice, in order to avoid the improper selection of cost loss and efficiency reduction.
Before selecting the type, first of all, we must clarify the measurement requirements, including the type of medium to be measured (gas, liquid or steam), flow range, pipe size, and measurement accuracy and so on. Vortex flowmeter is suitable for a variety of media, but the measurement characteristics and requirements of different media are different, so you need to choose the right model and specifications.
1. Flow range: should ensure that the commonly used flow rate is located in the upper middle of the measurable range of the vortex flowmeter, to avoid the impact of pipeline vibration in the measurement of the lower limit. If the flow range is beyond the vortex flowmeter's measurable range, you can consider the use of shrinkage or expansion methods, but note that shrinkage may increase resistance and back pressure, and expansion may appear cavitation.
2. pipe size: vortex gas flow meters pipe size should be matched with the size of the pipe being measured to ensure measurement accuracy and fluid stability. At the same time, the length of the straight pipe section will also affect the stability of the fluid measurement, so it needs to be considered comprehensively when selecting the type.
The characteristics of the measured medium are critical to the selection of vortex flow meters. The medium's temperature, pressure, density, viscosity and whether it contains impurities will affect the measurement accuracy and stability of the flow meter.
1. Medium temperature: vortex flowmeter is usually suitable for normal temperature, medium and high temperature range of media. If the site media temperature is higher, such as superheated steam, you may need to use other types of flow meters, such as orifice plate flowmeter. 2.
2. medium pressure: nominal pressure is also an important basis for selection, it is mainly based on the installation method to divide. For example, the nominal pressure of the French card mounted vortex flowmeter for 5MPa, while the insertion of the installation type may be 6MPa, 5MPa or 0MPa.
3. Medium characteristics: vortex flowmeter is not suitable for measuring pulsating flow, so you need to confirm whether the piping system has power mechanical equipment may produce strong pulsation, in order to avoid measurement errors due to the pulsation frequency and vortex frequency similar to the measurement error. At the same time, for corrosive media, should choose corrosion-resistant flowmeter material, and consider the internal structure of the flowmeter and sealing performance.
Measurement accuracy and repeatability are important performance indicators of vortex gas flow meters, they reflect the accuracy and stability of the flow meter measurement results.
1. Measurement accuracy: the accuracy level of vortex flow meter depends on the measured medium. For example, the accuracy of pipeline vortex flow meter for liquid can be up to 0 level, and the accuracy of gas can be up to 5 level. When selecting the type, you should choose the appropriate accuracy level according to the actual demand.
2. Repeatability: In the same measurement conditions, the same measured medium for multiple measurements, the consistency between the measurement results is called repeatability. The better the repeatability of the vortex flowmeter, the higher the stability of the measurement results.
The installation conditions and environmental factors of vortex flowmeter will also affect its measurement performance. Therefore, when selecting the type, it is necessary to comprehensively consider the installation location, pipeline layout, straight pipe length, vibration conditions, electromagnetic interference and protection level and other factors.
1. Installation location: should ensure that the flowmeter away from strong magnetic fields and mechanical vibration to reduce external interference. At the same time, the flowmeter should be installed in the area of smooth fluid flow, avoiding close to elbows, valves and other components that interfere with the flow.
2. straight pipe section length: vortex gas flow meters have certain requirements for straight pipe sections, generally require the first 10D after 5D (D is the diameter of the pipeline) of the length of the straight pipe section to ensure fluid stability. If the straight pipe section is not enough, it may affect the measurement accuracy.
3. Protection level: the commonly used IP protection level of vortex flowmeter includes IP65, IP67 and IP68. when selecting, the appropriate protection level should be determined according to the installation location of the vortex. For example, IP65 is usually chosen for indoor installation; for outdoor location above ground, higher protection level is needed; if installed in the ditch below the outdoor ground, IP68 and separated amplifier should be chosen to prevent damage by water immersion.
vortex gas flow meters have various types of output signals, the common ones are voltage-frequency pulse output, two-wire 4-20mA output and HART output. When selecting the type, you should choose the appropriate signal output method according to the requirements of the control system. Meanwhile, vortex flowmeter usually needs external power supply to work normally. When selecting the type, the suitable type of power supply (e.g. AC, DC) and voltage level should be chosen according to the site conditions, and the stability and reliability of the power supply should be considered.