Problems with balanced flow meters
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I have a wastewater treatment project that requires an aeration system. The flow meter selected for the aeration pipes is a balanced flow meter with a capacity of 160 m3/h. The aeration fan used is one of the existing fans in the plant, with an air delivery capacity of 130 m3/min; this fan also supplies air to other parts of the plant, but it’s not clear what the volume of air delivered will be. What effect will it have on the balance flow meter if the air volume from the aerator coming in is much larger than 160 m3? Will it cause damage to the porous orifice plates of the flow meter, or will it damage the differential pressure transmitter? If any colleagues are aware of this, please advise
It will not cause damage to the flow meter and transmitter
If I were to answer your question simply, it won’t have any impact on the flow meter’s balance; the hardware won’t get damaged. However, you need to check the transmitter to ensure that the maximum allowable differential pressure isn’t exceeded, as this can lead to damage over time.
To go a step further, if you feel that the actual flow rate is too high and the measuring range of the instrument is insufficient to display the actual values, you can consult the instrument manufacturer. Its maximum measurement range should be larger than yours; generally, the measurement ranges of flow meters are quite wide. For example, if your current flow rate is 160, the instrument in question might be able to measure up to 500 or even higher. If you have an estimated value, such as 500, you can ask whether it’s possible to measure that value, and if so, what adjustment needs to be made to the differential pressure Just have him prepare a new calculation sheet for you.
A balanced flow meter can be considered, in terms of its structure, as a porous orifice plate. Manufacturers usually leave sufficient spacing between the ring holes and the central hole to ensure adequate structural strength. From a safety perspective, an increase in flow rate does not have any adverse effect on the structure of the orifice plate. In terms of measurement, over time high flow rates can cause wear on the orifice, affecting the accuracy of measurements. On the other hand, an increase in flow rate may lead to changes in the Reynolds number and expansion coefficient, which in turn can affect the precision of actual measurements; however, this does not cause damage to the flow meter itself. For transmitters, an excessive flow rate will only lead to an out-of-range condition; as long as it does not exceed the gauge pressure rating of the flow meter, and for transmitters with standard ratings, this gauge pressure rating is in the MPa range. If operations are carried out in accordance with the regulations, no actual damage will occur to the transmitter itself – only the measurement and display results will be affected. If the flow rate increases only for a short period of time, there’s no need for the poster to worry about damaging the flow meter or differential pressure transmitter; the only impact will be on flow measurement, and as for how to resolve this, that’s another matter. If high temperature and high pressure conditions need to be considered separately, the manufacturer’s specifications shall prevail.