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Cumulative flow measurement instrumentation

Q: What is the instrument that can take a cumulative flow measurement of an effluent slurry containing fibers? I am required to measure the quantum of effluent that I send to a common effluent treatment plant. The effluent was generated by the dying operation of jute yarn and it contains jute fibers. Vanes of the flow meters (water meter) stops its running by these fibers. Is there is any electronic device like the energy meter (that is used to measure power consumption) available? Can a mass flow meter be used in this application?

A: If a volumetric flow measurement is sufficient, a correctly sized magnetic flow meter should be able to provide a repeatability of 0.25% of rate. Options exist for the materials used for the wall and electrodes if the fibers are abrasive. If you need much better performance, the considerably more expensive Coriolis mass flow meter has a repeatability of 0.04% of rate and offers a true mass flow, density and percent solids measurement. Again, materials of construction must be reviewed for abrasion.

To get a cumulative (total) flow, the measurement signal of flow rate is sent to a flow integrator (totalizer) that has a zero drop-out feature where the flow reading is zeroed out when the flow drops below a low flow limit. This drop-out feature is important to prevent the integration of noise and negative flow signals when the signal is below the low flow limit of the meter (e.g. signals below 5% for a magnetic flow meter and 1% for a Coriolis flow meter).

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