How to choose the right flow meter from the wide variety of available ones
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This post was last edited by O.K. on 2015-6-23 09:22. Flowmeters have a history of several hundred years; with the advancement of technology and changing demands, a variety of flowmeters have been developed, with an increasing number of types available. Moreover, when measuring the same type of fluid, multiple flowmeters may be suitable for the task. For example, electromagnetic flowmeters, vortex flowmeters, and turbine flowmeters can all be used for measuring water. But which one is more suitable after all? And when the prices are similar, which one is better to choose? Here lies the importance of selection. Choosing the right flow meter is a crucial factor for its subsequent use. No flow meter is perfect and capable of functioning properly in every environment under all conditions; when making a selection, we need to focus on its advantages to enable the meter to deliver its best performance and maximum effectiveness. For example, in terms of accuracy, electromagnetic flowmeters and vortex flowmeters offer higher precision. In terms of price, glass rotor flowmeters are more affordable. However, compared to glass rotor flowmeters, electromagnetic flowmeters have better pressure resistance and can measure larger flow rates. Lifespan is also a factor that needs to be considered, among other things. These are all issues that need to be taken into consideration when making a selection; below, we will go into detail about the various factors involved in such selections. Selection criteria: The selection of a flow meter can generally be considered from five aspects, namely instrument performance, fluid properties, installation conditions, environmental conditions, and economic factors. 1. Instrument performance aspects: accuracy, repeatability, linearity, range, flow range, signal output characteristics, response time, pressure loss, etc ； 2. Fluid properties: temperature, pressure, density, viscosity, chemical corrosion, abrasiveness, scaling, multiphase flow, phase transformation, electrical conductivity, sound speed, thermal conductivity, specific heat capacity, etc ； 3. Installation conditions: pipeline layout direction, flow direction, length of the straight sections upstream and downstream of the sensing element, pipe diameter, maintenance space, power supply, grounding, auxiliary equipment (filters, degasers), installation, etc ； 4. Environmental conditions: ambient temperature, humidity, electromagnetic interference, safety, explosion protection, pipeline vibration, etc ； 5. Economic factors: cost of instrument purchase, installation costs, operating expenses, calibration fees, maintenance costs, service life of the instruments, spare parts, etc.
:I feel like this post says nothing at all. . . Try not to copy and paste; share your own experiences instead
I work with external ultrasonic flowmeters. Based on my experience in this field, when choosing an external ultrasonic flowmeter, factors such as pipe diameter, material, the liquid being measured, lining, and impurity content should be taken into consideration. If the impurity content or bubble content is greater than 10%, it is advisable to use a Doppler flow meter, which is also of the clamp-on type
What type of flow meter can measure flow even with 10% bubbles? Please share the relevant information
I want to tell you that I won’t send attachments; I’ll only type! If you work in the flow measurement industry, you should be well aware that there are many types of flow meters, but they can be classified into two categories based on the method of installation: in-line and clamp-on. External clamping types are generally ultrasonic, and they are mainly divided into two categories: the time-difference method and the Doppler method. It is used to detect particles larger than 40 microns, such as those containing sediment, impurities, or bubbles, when their concentration is 10% or higher
You can take a look at the FC6P Doppler flow meter from American company Nonamec; I work on this model
At the same time, due to the limitations of the measurement principle of Doppler ultrasonic flowmeters, the fluid being measured must have a turbidity of at least 50 mg/L; clean fluids cannot be measured using these devices； However, if too many bubbles get mixed into the fluid, it often leads to unstable measurements and missed detections ； Also, in principle, the flow velocity of solid particles or bubbles in the fluid is used as a substitute for the fluid’s flow velocity; these particles and bubbles are present randomly, and their sound transmission properties also vary. All these reasons result in the measurement accuracy of Doppler ultrasonic flowmeters being slightly lower than that of time-difference types; it is generally on the order of 2.0 grade, meaning an error of 2% of the full scale (2% F.S.). It’s already quite good; everyone can use it as a reference
However, in such a liquid environment, flow meters that rely on time differences cannot detect it; only Doppler can! Like drilling fluid!
It’s not expressed that way; in some areas, ultrasonic waves are more useful, for specific environments and specific applications. The precision you mentioned probably refers to their use in trade transactions. Ultrasonic flowmeters are now widely used, and the technology behind them is highly mature.