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Determining the range over which a more appropriate steam flow meter may be used.

The Velocity Pressure value will be provided by either ACI’s DLP or MLP2 differential pressure transmitter paired with a PT Differential Pitot Tube installed in the duct.

To find the Flow Velocity, use this equation: FPM 4005 x P (The square root of the Velocity Pressure). Occasional use to provide an indication of flow rate Finding the Flow Velocity in feet per minute (FPM) is the first step.Placement inside the pipework is critical.The low pressure drop measured by the unit, increases uncertainty, especially on steam.Sensitive to changes in turbulence and needs careful installation and maintenance.To counter this, some models can be installed horizontally. If steam is wet, the bottom holes can become effectively blocked.Turndown is limited to approximately 4:1 by the square root relationship between pressure and velocity.Simple types can be used on different-diameter pipes.

These sensing tubes sense various velocity pressures across the pipe, which are then averaged within the tube assembly to give a representative flow rate of the whole cross-section. Theoretical Velocity for Pitot Tube is defined as the velocity that is calculated theoretically using pitot tube is calculated using Theoretical Velocity sqrt (2 Acceleration Due to Gravity Dynamic Pressure Head).To calculate Theoretical Velocity for Pitot Tube, you need Acceleration Due to Gravity (g) & Dynamic Pressure Head (h d). The averaging Pitot tube (Below Figure) was developed with a number of upstream sensing tubes to overcome the problems associated with correctly siting the simple type of Pitot tube. The transducer output is then used to calculate a velocity that is not the actual velocity of the flow. If the tubes become clogged or pinched, the resulting pressures at the transducer are not the total and static pressures of the external flow.There are corrections for the shock wave that can be applied to allow us to use pitot-static tubes for high-speed aircraft. At the front of the tube, a shock wave appears that will change the total pressure. If the velocity is very high (supersonic), we’ve violated the assumptions of Bernoulli’s equation and the measurement is wrong again.Errors in the instrument could be greater than the measurement! So pitot-static tubes don’t work very well for very low velocities. If the velocity is low, the difference in pressures is very small and hard to accurately measure with the transducer.There are some practical limitations to the use of a pitot-static tube: Where: u 1 = The fluid velocity in the pipe Δp = Dynamic pressure – Static pressure ρ = Density

Calculate velocity using a pitot tube