Under no flow conditions in downward flow, the pressure actually increases through the flowmeter as a result of static pressure due to decreasing elevation.
What are the approximate pump speed, pressure and mechanical load at 50% flow?
Normally, liquid will flow downward by gravity. However, when a vacuum is applied to a vessel, liquid may flow upward from below — like drinking through a straw.
What is the rule of thumb for the amount of straight run required upstream and downstream of a flowmeter?
Systems operating under a vacuum are more likely than a pressurized system to inadvertently operate below the vapor pressure of the liquid.
Where and how should a differential pressure flow transmitter be located for liquid service?
Accurate flow measurement entails a larger magnitude of compensation for pressure and/or temperature.