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How is mass flow measured based upon differential pressure technology?

A Pitot tube flow meter is a differential pressure device that measures the velocity of a gas based on Bernoulli’s principle. It uses two pressure points. The stagnation port captures the impact pressure of the flowing gas, while the static port records the static pressure inside the pipe. The difference between these two pressures gives the differential pressure, which increases with higher gas velocity.

To determine the mass flow rate, the measured differential pressure is combined with temperature and system pressure. These parameters define the density of the gas, which is essential for converting velocity into mass flow. With this approach, a Pitot tube flow meter provides a reliable method to measure mass flow in compressed air and gas systems, supporting stable operation and consistent consumption monitoring.

What is the difference between standard and actual flow?

The actual flow rate is the volume of a gas somewhere in the system, independent of its density, that flows through a certain point. The term actual flow rate is not clear, when it comes to the mass of a gas flowing through a given point, because gas is compressible. If the pressure is doubled, then for an ideal gas, the mass which flows at a constant flow rate through a particular point is also doubled. To take this enlarged mass flow into account, for gases usually the standard volumetric flow is used, because this is based to certain standard conditions and is thus comparable to the mass flow. In compressed air the standard usually is at 1 bar absolute and 20 degrees C.