Analysis on the precision and repeatability of electromagnetic flowmeter
Analysis on the precision and repeatability of electromagnetic flowmeter
The specification of the flowmeter is a key factor in choosing which one is appropriate for your application. Two important statistics are their accuracy and repeatability. Let's first explain what these two parameters mean:
Flowmeter accuracy
Accuracy is how close the measured value is to the real value. In the case of an electromagnetic flowmeter, this means that the output of the meter is close to its calibration curve. This is expressed as a percentage, such as ± 1%. This means that any given reading may be 1% above or below the calibration curve. In general, it can be said that the lower the percentage, the more accurate the meter. However, it also depends on the specification of FS (full range) or Rd (reading). The meanings of Full Scale and Reading will be explained later in this blog.
Flowmeters became more and more accurate, especially with the advent of electromagnetic flowmeters.
Flowmeter repeatability
Repeatability produces the same results under the same conditions. In other words, the electromagnetic flowmeter should produce the same readings when operating in the same variables and conditions. This is also expressed as a plus or minus percentage.
Although accuracy is often the focus of the measurement field, repeatability is the basis of accuracy. You can achieve high repeatability without high precision, but without high precision, you cannot achieve high precision. It is of no use if the meter is highly accurate only for a period of time. If your data is unreliable, and if you get different Numbers in the same environment and Settings, it's unlikely that all of them will be accurate.
Does accuracy always matter?
No one wants an inaccurate meter, but not all applications require high precision. If you only want to know how much flow is in the pipe, further deviation from the calibration curve is acceptable. It is not acceptable if you mix drugs for consumption or volatile elements. When choosing electromagnetic flow timing, the accuracy of the meter is very important, because usually the more accurate the meter, the higher the price.
When you see the precision specification, it should be expressed as the percentage of full range (FS) or reading (Rd or Rd). The differences between these can be large.
Full Range (FS) and Reading (Rd)
When the reading depends on the physical mark on the dial, the full range is actually the carryover of the mechanical instrument. Digital instruments can now provide more accurate readings, so high-end instruments often use readings rather than full range.
While you do not need an inaccurate flowmeter, not all applications require high precision.
In terms of mass flow, precision requirements can vary the type of sensor discussed. If you need very high precision, you can use an electromagnetic flowmeter; if high precision is not important, you may need a constant temperature wind speed (CTA) or other sensor type.
What is full range (FS)?
A full range is defined as "the degree of closeness to the actual value, expressed as a percentage of the value of a good proportion".
With full range, the error remains the same, but the percentage changes as the flow goes up and down in the flow range. If the accuracy is calibrated to 1% of 200 ln/min, the error is 0.01x 200 ln/min = 2 ln/min. If the flow rate is 100 ln/min, the error is still 2 ln/min or 2%, a much larger percentage.
What is reading (Rd or Rd)?
Reading (Rd) is defined as "the degree of closeness to the actual value, expressed as a percentage of the actual value.
When reading, accuracy is the percentage of what is read. No matter where the traffic is in the traffic range, the percentage remains the same. If 1% at 200 ln/min, 1% at 100 ln/min. Therefore, the error of 200 ln/min flow will be 2 ln/min, but for 100 ln/min, it will be the full range of 1 ln/min instead of 2 ln/min.
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