Measurement performance of mass flow meters when the medium flows in the reverse direction

I’m not very familiar with mass flow meters, and I’m not sure whether it’s possible to measure two-way flow. If such measurement were possible, then the original poster wouldn’t have to worry so much

Theoretically, mass flow meters can measure in both directions, but it’s not clear what the actual situation is in practice; you can consult the technical staff of reputable manufacturers of imported mass flow meters for information on this.

This post was last edited by backcat666 on 2012-1-5 21:41. Electromagnetic flowmeters can also measure two-way flow, but they have two disadvantages compared to mass flowmeters: (1) they are only suitable for measuring conductive liquids； (2) Output is only possible in one direction. Flowmeters capable of detecting two-way medium flow currently exist only in the form of mass flowmeters and electromagnetic flowmeters with such detection capabilities; it is because these two types of flowmeters have no resistive elements inside the measurement tube that they can detect flow in both directions. Some ultrasonic flowmeters will work as well, but not all of them. Flow meters with resistive elements inside the tube cannot perform two-way measurement due to the significant differences in the flow conditions when the medium flows in either direction. Theoretically, an electromagnetic flowmeter can detect flow in both forward and reverse directions, but it is necessary to configure the forward or reverse function in the software. Due to the oscillating element used in mass flow meters, reverse flow can be detected only when the installation and driving method of this element in the measurement tube are appropriate; moreover, corresponding software or functional settings are required. These functions require confirmation based on the manufacturer’s specification documents.

Mass flow meters can perform measurement in both directions. But you need to pay attention to two issues: 1. Whether measurement is required for loading the ship, and if so, a direction must be specified. Because meter-grade mass flow meters lock or secure their parameters after proper adjustment, in order to prevent operators from changing them arbitrarily and causing inaccurate outputs. Even if there is an output due to reverse flow, you cannot use it because the accumulator will not function. 2. If measurement is not required, the parameters can be adjusted in the table header to read the instantaneous flow rate as well as the cumulative flow rate. The pulse output of the mass flow meter has a 90-degree or 180-degree phase shift to indicate the flow direction; therefore, corresponding adjustments must be made. If it’s metered, you can’t adjust it, so it “can’t” be used.

Theoretically, mass flow meters can be used in reverse, but it is still best to use them in the direction indicated by the arrows on the instrument! You can ask the manufacturer if it’s okay to use it in reverse; if there are no issues, then go ahead and use it!

From what the poster meant, it seems that a single flow meter is used for both forward and reverse flow measurements. Although such a meter can measure in both directions, it is difficult to maintain accuracy during reverse measurements. Especially since standard calibration always involves forward flow, it is better to use forward flow measurement for purposes related to trade calculations. Since both forward and reverse media use the same pipeline and flow meter, why not add a transverse line and a return line next to the flow meter? Adding a few more valves will not incur significant costs; simply adjusting the piping and using a forward-flow meter for measurement will suffice.

Mass flow meters can measure in both directions, but during calibration only the forward direction is calibrated; if necessary, calibration in the reverse direction can also be carried out, and there will be no problems as long as it is successful. From the manufacturer’s perspective, there is no issue with this