Answer / carl_ellis

Yokogawa mass flow meter shows negative reading...what r the main causes for this problem?...

Impossible to say, because the technology is not stated, nor are the conditions stated.

Yokogawa is a brand name, not a technology, and the reason for a negative flow indication depends on the technology.

Technologies for mass flow (however inferred) are
- multivariable flow meters based on pressure and temperature compensated differential pressure
- Coriolis flow meters
- Vortex flow meters with temperature and pressure compensation
- Thermal dispersion flow meters
which might or might not be Yokogawa products.

The reasons for a false negative flow indication could be quite different for any of the technologies

Conditions like the expected flow rate vs the observed flow rate, medium, medium temperature and pressure, service history, installation details (vertical or horizontal), flow path, type of pump, process function or contiguous piping and its orientation, and configuration elements like low flow cutoff could contribute to an indicated negative flow rate, or operational method of zeroing.

Because it could be that you actually have reverse flow from a thermal syphon or a pressure syphon.

Carl Ellis
Measure First

Answer / manikanta

Flow will may be in revers direction

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