Solving pipeline balanced flow meters?

Is there a type of flow meter that can measure an infinite flow rate?

It’s the principle of differential pressure; as long as there is a passage, a differential pressure will be generated, and thus it can be measured, right? So I’m quite confused: is there any limit to the upper measurement range for this differential pressure principle?

When the flow rate exceeds the choked flow rate, there is no correlation between flow rate and differential pressure.

I think it depends on how much the pipeline can handle. I believe that as long as the pipeline is large enough, this type of balance can perform measurements; it has a range limit. If the upper limit is set too high, low flow rates won’t be detectable. I’m not sure about this, which is why I came here to ask

Mm-hmm, yes. So everything works fine before the flow is blocked. But could it be that a low flow rate won’t be detected?

The balance flow meter itself has no limitations regarding the range ratio, but pressure differential transmitters do have such limitations. The square of the flow rate is proportional to the pressure differential; therefore, a flow rate range of 3:1 corresponds to a pressure differential range of 9:1. Currently, no pressure differential transmitter can achieve a range ratio of more than 10:1

Generally, a control range ratio of 10:1 is preferable, as it ensures accuracy at low flow rates. I have encountered situations where the designed range ratio was 10:1, but under actual operating conditions the ratio became 30:1; in such cases, it becomes almost impossible to measure low flow rates. The solution is to recalculate and set the range based on the actual operating conditions. However, since the pipe diameter and throttling elements are already fixed, it’s only possible to measure low flow rates, and errors still exist when dealing with high flow rates. Additionally, the model (range) of the transmitter plays a role here; for example, transmitters with a range of 0-40 KPa are not as sensitive when measuring low flow rates as those with a range of 0-7.5 KPa

This post was last edited by seiluobin on 2016-6-15 at 10:40. Balanced flow meters are said to be capable of measuring flow without any upper limit, but they have requirements regarding the Reynolds number of the fluid, and the calculation of the orifice dimensions must be precise. As mentioned below, when flow exceeds the critical level, the relationship between differential pressure and flow rate changes – the differential pressure increases while the flow rate no longer rises. However, it’s certainly not possible for the flow velocity to be that high during design. . . Generally, the upper limit for liquid flow velocity is 3 m/s, while for gases it is 25 m/s. So there’s no need to worry about this issue. Additionally, in certain special situations, the differential pressure and flow rate seem to have a purely linear relationship; I forget what those situations are now, but I’ve seen them before