Friction Loss in a Pipe

These sheet calculates the pressure drop in a length of pipe for a specified flow rate. The pipe is assumed to have a circular cross-section. First, the volumetric flow rate, Q, the pipe internal diameter, D, and the length, L, are all defined:
Next the fluid is selected from the table below. Note, that by default, the unused rows in the table are hidden. To see all of the rows in order to change the fluid selection, click the button. Once the desired fluid is selected, the unused rows can be hidden by clicking the button. This allows large tables to be used without taking up much vertical space in the sheet.Table data source: Gieck and Gieck, Engineering formulas. 2006.
Water, 20 ℃
In order to calculated the pipe friction, it is necessary to specify the specific roughness of the pipe. General design values for various pipe materials are listed in the table below. Table data source: Lindeburg, Mechanical Engineering Reference Manual, 13th ed. 2013.
Steel

Concrete, clay, or brick

Cast iron

Plastic (PVC, ABS, and HDPE)

Fiberglass

Glass
In order to calculate the average flow velocity, v, in the pipe, it is necessary to calculate the cross-sectional area. The volumetric flow rate can than be divided by the cross-sectional area to obtain the average flow velocity.
The friction factor for the pipe depends on the Reynolds Number, Re, of the flow. For a round pipe, the Reynolds number can be calculated as:
2.34649244993566\times 10^{5}
The friction factor equation depends on whether the flow is laminar or turbulent. In general, flow with a Reynolds number below 2100 is considered laminar and flow with a Reynolds number greater than 4000 is considered turbulent. Flow with a Reynolds number between 2100 and 4000 is in the transition region. For flow in the transition region, it is conservative to use the turbulent flow friction factor since it will be greater than the laminar friction factor. Based in the Reynolds number value above, choose the correct friction factor equation in the table below:
Laminar Flow

Turbulent Flow (Swamee-Jain Equation)
Now that the friction factor is defined, the head loss due to friction in the pipe can be calculated using the Darcy-Weisbach equation:
=50.7723992569856 ft
Finally, the pressure drop due to the pipe friction can now be calculated from the head loss:
=21.9813187924092 psi

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