A chemical plant needed continuous flow measurement on a concentrated sulfuric acid transfer line feeding a control loop. Two constraints made every conventional option impossible.
The line could not be broken. Cutting into an acid line means a shutdown, a drain, a neutralization, and a hot work permit — and it creates a new flanged joint on a service where every joint is a future leak.
Every wetted meter is a consumable here. A mag meter's electrodes foul and its liner degrades. When it eventually fails, it does not stop reading — it becomes a leak path for concentrated acid.
A permanent clamp-on transit-time installation. The transducers mount on the outside of the pipe: nothing in the stream to corrode, no new joint, no shutdown to install.
The line runs full and the acid is acoustically clear, which puts it firmly in transit-time territory. The Ultraflux Minisonic Fixed is specified for water, acids, alkalis and chemicals, gives 0.5% of reading (not of full scale), and provides an isolated 4–20 mA output plus Modbus TCP for the control system.
Percent of reading, not percent of full scale. A meter quoted at 0.5% FS is 5% off the reading when the line runs at 10% of range. Percent-of-reading holds across the turndown.
Isolated outputs. A non-isolated 4–20 mA on a long run in a plant environment is a ground loop waiting to happen, and the symptom is a reading that wanders in a way nobody can trace.
Gain trending. The commissioning gain was recorded as a baseline and put on the historian next to flow. On a permanent installation, a slow upward creep in gain is couplant degradation caught months before the reading fails.
On an aggressive-service line, the argument for clamp-on is not primarily accuracy or cost. It is that there is nothing in the pipe to fail — and a wetted meter that fails on an acid line is a safety event, not a maintenance ticket.
Send us the pipe and the fluid and we will tell you what will actually work.
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