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FAQ Compressible Gases

Flow of Fluids Premium uses the Darcy-Weisbach method for calculating the pressure drop in a pipeline. This method assumes the density of the fluid is constant in the pipeline. The Crane Technical Paper 410 states that the Darcy-Weisbach method provides satisfactory results under the following conditions:

If the calculated pressure drop is less than 10% of the inlet pressure, then reasonable accuracy will be obtained if the density used for the fluid is based upon either the upstream or the downstream conditions.

If the calculated pressure drop is greater than 10%, but less than 40% of inlet pressure, reasonable accuracy can be achieved using the density based on the average of the upstream and downstream conditions.

For pressure drops larger than 40%, use a method that incorporates the compressibility of the gas.

In addition, some resources indicate that the Mach number must not exceed 0.1 to 0.2 in order for compressibility effects to be assumed negligible.

Using the above guidelines Flow of Fluids Premium can provide accurate results for gas distribution systems found in plants and buildings.

If you have additional questions about Flow of Fluids Premium, please feel free to contact Flow of Fluids.

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