What does it mean to take the square root of a flow meter?
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What does it mean to take the square root of a flow meter? When is it necessary to take a square root?
In all the flow measurement methods using differential pressure that I’ve seen, square root calculation is required, whether it’s in the transmitter or in the upper-level instrumentation.
Because, within a certain range, there is a linear relationship between the differential pressure value and the square of the flow rate.
This post was last edited by qugd on 2017-3-3 at 15:43. In differential pressure flow meters, the square root of the differential pressure value is proportional to the flow rate; therefore, if the signal output of the flow meter is in the form of differential pressure, then taking the square root is necessary to convert it into a flow rate signal. The original poster should take a look at the Bernoulli expression and will understand right away. Put simply, it is the loss of potential energy caused by the pressure difference in the medium that is converted into kinetic energy of the medium flowing through the pipe, represented by flow velocity; that is, ΔP ∝ 1/2 mV2, so V ∝ √ΔP
The original poster should study the principles of chemical engineering carefully; the squaring of the differential pressure reading from a differential pressure flow meter is usually done within the DCS system, as no squaring is performed on-site
If a differential pressure transmitter is installed on-site, it is entirely possible to apply a square root operation to the transmitter’s output signal, thereby eliminating the need for the DCS to perform such an operation. The differential pressure signal at the site is squared to facilitate display on the on-site gauge; as a result, the flow signal corresponding to the signal displayed on the gauge is linear. This has nothing to do with the principles of chemical engineering; it is related only to the method of signal processing. In the past, there were also on-site pneumatic or electric differential pressure indicators, along with dedicated square-rooting devices for signal processing.
A flow meter requires taking the square root only when measuring using differential pressure, as flow rate is proportional to the square of the differential pressure. Moreover, it’s not necessary to take the square root of the value from the differential pressure transmitter in all cases; this depends on what is being measured using that differential pressure. If it is differential pressure or level, it is not necessary; in other words, signal processing is involved.
The differential pressure flow meter requires taking a square root. There is no linear relationship between differential pressure and flow rate; rather, it is a square root relationship. This is derived from the basic formula for flow, the Bernoulli equation. If you have time, take a look at fluid mechanics or the \"Design Manual for Throttling Devices in Flow Measurement\"
With square-root calculation, the flow rate is too low and the process is not satisfactory; but isn’t it possible to avoid losses with such a low flow rate? That’s why square-root calculation is used, which increases the value.
Differential pressure type flow meters: According to the formula, flow rate is proportional to the square root of the differential pressure