Electromagnetic flowmeter selection and use of tips

The selection and usage skills of electromagnetic flowmeter are as follows:

Selection of caliber and flow rate: The caliber of electromagnetic flowmeter is not necessarily the same as the pipe diameter and should depend on the flow rate. The economic flow rate of pipelines is generally 1.5 to 3m/s. If the flow rate is low, from the perspective of measurement accuracy, it is necessary to reduce the diameter at the location where the instrument is installed, and ensure straight pipe sections at the front and rear, or use reducing pipes to connect them.

Full-scale flow rate and upper limit flow rate: When the electromagnetic flowmeter reaches full-scale flow rate, the liquid flow rate can be selected in the range of 1 to 10m/s. The upper limit flow rate is not limited in principle, but it is usually recommended not to exceed 5m/s, unless the lining material can withstand liquid erosion. Practical applications rarely exceed 7m/s, and exceeding 10m/s is even rarer. The lower limit of flow velocity for full-scale flow is generally 1m/s, and for some models of instruments, it is 0.5m/s.

Installation and matching: When used in pulsating flow situations, attention should be paid to the flow meter's response to flow step changes. Some applications require the flowmeter output to follow the fluid flow, while others require a slower response output to obtain a comprehensive average. Instantaneous response is often expressed in terms of time constant or response frequency, the former ranging from a few milliseconds to a few seconds, and the latter below hundreds of Hz. The use of a display instrument may significantly extend the response time.

Fluid characteristics and adaptability: When evaluating various parameters of the fluid under usage conditions and selecting the adaptability of the flow meter, the density, viscosity, vapor pressure and other parameters of the fluid need to be considered. These parameters can generally be found in the manual. But there are also some physical properties that cannot be found. Such as corrosiveness, scaling, clogging, phase change and miscible state, etc.

In general, there are many factors to consider when selecting and using an electromagnetic flowmeter correctly. The above content is for reference only. It is recommended to consult professional books or consult professionals to obtain more comprehensive and accurate information.